3 Ways Tool Coatings Increase Tool Life

Cutting tools are commonly found with an ultra-thin molecular compound coating applied to its cutting surfaces. These coatings are engineered to combat against forces that wear down your cutting tools and lead to catastrophic tool failure. Not only are coatings created for cutting specific materials, but they also limit heat and friction and enhance the performance of your tool. When selecting a coated tool, the machinist must consider how the material and desired cutting operations may break down the cutting edges of the tool, to determine which coating will best serve their needs. Before those decisions can be made, one must understand how coatings increase a tool’s cutting abilities. The following is an in-depth look into the benefits provided by tool coatings and how they work to improve tool life and performance.

What Is a Coating?

Tool coatings consist of organic and inorganic compounds which are applied and adhered onto the substrate using Physical Vapor Deposition (PVD) or Chemical Vapor Deposition (CVD). Compounds are deposited onto the tools in layers until a desired thickness is achieved.

Coated cutting tools provide three main functions:

  1. Provide a thermal barrier between the tool and workpiece
  2. Improve tool lubricity
  3. Increase tool wear resistance

With the proper utilization of these three features, cutting tools can be pushed much harder, run with faster cycle times, and last longer.

1.      Provide a Thermal Barrier Between the Tool and Workpiece

Heat mitigation is essential in machining, as excessive tool and workpiece heating during cutting operations can be detrimental. As the carbide tool’s temperature rapidly increases, its hardness decreases, resulting in greater wear and burn out. Thermal conductivity is a material property used to measure a material’s ability to retain or transfer heat energy. For example, tungsten carbide has a thermal conductivity of 88 W/m.K at 20°C. This means at room temperature, 20°C (68°F), an uncoated carbide tool can conduct 88 Watts of thermal energy per meter with a temperature gradient measured in Kelvin. The materials used in tool coatings do not conduct heat as well with thermal conductivity rates as low as 4.5 W/m.K. This means that a coating with a thermal conductivity of 4.5 W/m.K, the coating would transfer 19.56 times less heat than tungsten carbide.

An experiment showcasing the thermal abilities of coatings is shown below. Both an AlTiN Nano coated tool and uncoated tool were turning 4340 steel at a speed of 155 m/min (508.5 ft/min) and 200 m/min (656.17 ft/min), at a feed rate on 0.5 mm/rev (0.019 in/rev) and a depth of cut of 3.5 mm (0.138 in) [1]. No coolant was used.

uncoated tool thermal gradient

Figure 1: Thermal gradient of the cutting tip of the uncoated tool [1].

tool coatings thermal gradient

Figure 2: The above images, found in a study titled “Experimental Study and Modeling of Steady State Temperature Distributions in Coated Cemented Carbide Tools in Turning,” written by Amol Thakare and Anders Nordgren, showcase the effects of cutting tool speed and tool deformation on temperature distributions in unworn (left) and worn (right) tool.

Comparing the two tools, it is clear that the coated tool absorbs far less heat than the tool without a coating. With lower thermal conductivity rates, tool coatings create a thermal barrier between the carbide and workpiece. This greatly decreases the internal temperature of the carbide as the heat generated during the cutting operations is redirected into the chips and workpiece. With lower temperatures, faster cutting speeds can be attained. Looking at the thermal gradients above, the uncoated tool running at 155 m/min and the coated tool running at 200 m/min roughly have the same surface temperature. This means the coated tool can run 22.5% faster than its uncoated counterpart.

2. Coatings Increase Tool Lubricity

Another key to limiting heat generation and keeping cutting smooth and chatter-free is to decrease the amount of friction between the cutting tool and workpiece. Frictional force is the resistance to motion, and in the case of cutting tools, the force opposing the lateral and radial movements of the tools as it cuts through the workpiece. This opposing force is determined by the coefficient of friction, often denoted as the Greek letter Mu (μ). The friction coefficient is the ratio between the force required to move one surface across another, divided by the pressure between the two surfaces. Minimizing μ is how coatings decrease the overall frictional forces involved in cutting operations because the force of friction is directly proportional to μ.

An example to show how much a coating can reduce the coefficient friction during cutting operations, over an uncoated carbide tool, is shown in the study performed by the University of Technology of Malaysia. In this experiment, 1040 carbon steel was turned at 60 mm/min (2.36 in/min), a depth of cut of 1 mm (0.04 in), a feed rate of 0.06 mm/rev (0.0024 in/rev), and a repeated length of cut of 100 mm (3.937 in) until the tool cut a total length of 1000 m (3280.84 ft) [2]. The coated tool had a TiCN coating, a coating similar to the more popular AlTiN coating. Below are the results:

Figure 3: The above image, found in “Friction and Wear Characteristics of WC and TiCN-coated Insert in Turning Carbon Steel Workpiece,” displays the friction coefficient of the TiCN coated tool and uncoated tungsten carbide tool.

As seen in figure 3, the TiCN coated tool had a much lower coefficient of friction than the uncoated tool. This lower coefficient decreases the frictional forces experienced during cutting operations, reducing heat generation, giving a better part finish, and extending tool life.

Selecting a coated tool with high lubricity would also be ideal for cutting materials with low melting temperatures, as well as materials that generate a tremendous amount of heat during machining, such as high hardness alloys. In materials with low melting points (such as aluminum or other non-ferrous metals), high friction can cause heat generation and sticking of chips. These chips can then cause chip packing in flute valleys and galling on the cutting edge. This galling is called built up edge (BUE) which creates a thicker edge and can break down the tool. With lower friction coefficients, it is more difficult for chips to stick to the tool and for BUE to occur. When cutting materials that would generate high temperatures (such as stainless steels and aerospace alloys), keeping frictional forces at a minimum, will reduce heat generation, and result in smoother cutting, preserving the tool’s cutting edges.

3.      Tool Coatings Increase Tool Wear Resistance

Adding a coating with a high microhardness rating increases a cutting tool’s ability to resist wear and avoid permanent deformations. In the cutting industry, cutting tool grades for tungsten carbide range from grades C1 to C14, depending on what the cutting operation the tool will be performing. Between grades C1 to C14, tungsten carbide has a Vickers Hardness (HV) ranging from 760 HV to 1740 HV. Tool coatings have higher microhardness ratings than tungsten carbide. Adding a coating can increase a tool’s hardness anywhere from 2213 HV using a TiN coating, to 9993 HV with the CVD diamond coating. While a TiN coating would not be chosen solely for its hardness, it shows that even the coating with the lowest hardness is still harder than bare tungsten carbide. By making the cutting tool significantly harder, the ratio of workpiece hardness to tool hardness increases. Increasing the tool’s hardness will allow it to shear off chips and remove material with greater ease, especially against high abrasive materials, while the tool maintains its structural integrity against the extreme forces experienced during cutting operations.

The benefits of increasing tool hardness with its improved performance are demonstrated in an experiment done by Afyon Kocatepe University. In this experiment, a 2 flute micro end mill with a cutting diameter of 4 mm was slotting into Inconel 718 at 20,000 rpm, with a feed rate of 5 micrometers per flute, a depth of cut of 0.2 mm and a length of cut of 120 mm [3]. This cut was performed using both an uncoated and AlTiN coated (3620 HV hardness) carbide end mill with no coolant. Below are optical comparator images of the two tools showing their wear and deformations.

Figure 4: The image above from “An Experimental Investigation of the Effect of Coating Material on Tool Wear in Micro Milling of Inconel 718 Super Alloy,” showcases an uncoated cutting tool.

Figure 5: The image aboves from “An Experimental Investigation of the Effect of Coating Material on Tool Wear in Micro Milling of Inconel 718 Super Alloy,” showcases the difference a coating can make on a cutting tool. Figure 4 displays an uncoated cutting tool, and figure 5 displays a cutting tool with AlTiN PVD coating.

Looking at the two tools, it is evident that the uncoated tool experienced significant flank and crater wear, which resulted in the flaking of its cutting edges. As this tool performed its cuts, flank wear occurred first. This wear happened directly at the cutting edge as the abrasive Inconel alloy began to breakdown the tool. As the flank wear increased past the cutting edge and into the rake face of the tool, crater wear formed. Crater wear is characterized by its depth into the tool. As chips slid across the rake face and increased this crater, pieces of the carbide tool began to flake off, forming a new, weaker cutting edge. This new edge is blunt and will not be capable for cutting the workpiece properly, and will continue to break apart until catastrophic tool failure occurs.

Flank and crater wear are two types of mechanical tool decay that are a direct result of the abrasiveness of the workpiece material. Increasing the microhardness of the cutting tool can combat against these abrasive modes of tool wear. This is proven in figure 5, as the AlTiN PVD coated end mill held up much better in comparison to the uncoated tool as it experienced minimal flank wear. As the coated tool performed its cuts, the only detectable wear was a microfracture along one of its cutting edges, and peeling of the AlTiN coating. The protection provided by the coating against abrasive wear is evident in this example, and with this protection, tool life is significantly increased.

The Benefit of Tool Coatings During Machining

Combining the three main advantages of a tool coating, thermal resistance, increased lubricity, and higher microhardness, not only does the tool perform better, but it lasts longer. Minimizing thermal and abrasive tool wear can substantially prolong tool life.

Citations

      [1] Thakare, Amol, and Anders Nordgren. “Experimental Study and Modeling of Steady State Temperature Distributions in Coated Cemented Carbide Tools in Turning.” Procedia CIRP, vol. 31, 2015, pp. 234–239., doi:10.1016/j.procir.2015.03.024.

      [2] Talib, R.J., et al. “Friction and Wear Characteristics of Wc and Ticn-Coated Insert in Turning Carbon Steel Workpiece.” Procedia Engineering, vol. 68, 2013, pp. 716–722., doi:10.1016/j.proeng.2013.12.244.

[3] Ucun, İ., Aslantas, K., & Bedir, F. (2013). An experimental investigation of the effect of coating material on tool wear in micro milling of Inconel 718 super alloy. Wear300(1-2), 8–19. https://doi.org/10.1016/j.wear.2013.01.103

Overview of Harvey Tool Coatings: Maximizing Tool Performance

Proper tool coating plays a large role during the selection of a CNC cutting tool. At Harvey Tool, coatings are optimized for specific materials and alloys to ensure the highest tooling performance, possible. Each coating offers a unique benefit for the cutting tool: increased strength, enhanced lubricity, heat resistance, and wear mitigation, just to name a few.  

In Benefits of Tool Coatings, the method of applying coatings to tools is examined. In this post, we’ll take a closer look at each Harvey Tool coating to examine its key properties, and to help you decide if it might add a boost to your next CNC application.

Harvey Tool offers a wide range of tool coating options for both ferrous and exotic materials, as well as non-ferrous and non-metallic materials. In the Harvey Tool catalog, coatings are often denoted in a -C# at the end of the product part number.

Harvey Tool Coating Gallery

Harvey Tool Coatings for Ferrous and Exotic Materials

TiN

TiN, or Titanium Nitride (-C1), is a mono-layer coating meant for general purpose machining in ferrous materials. TiN improves wear resistance over uncoated tools and aids in decreasing built-up edge during machining. This coating, however, is not recommended for applications that generate extreme heat as its max working temperature is 1,000 °F. TiN is also not as hard as AlTiN and AlTiN Nano, meaning its less durable and may have a shorter tool life.

Harvey Tool 46062 Tin Tool Coating

Harvey Tool 46062-C1

AlTiN

AlTiN, or Aluminum Titanium Nitride (-C3), is a common choice for machinists aiming to boost their tool performance in ferrous materials. This coating has a high working temperature of 1,400 °F, and features increased hardness. AlTiN excels in not only dry machining, due to its increased lubricity, but also in machining titanium alloys, Inconel, stainless alloys, and cast iron. To aid in its high heat threshold, the aluminum in this coating coverts to aluminum oxide at high temperatures which helps insulate the tool and transfer its heat into the formed chips.

altin tool coating 823816-C3

Harvey Tool 823816-C3

AlTiN Nano

AlTiN Nano or Aluminum Titanium Nitride Nano (-C6) is Harvey Tool’s premium coating for ferrous applications. This coating improves upon AlTiN by adding silicon to further increase the max working temperature to 2,100 °F while also increasing its hardness for increased tool life during demanding applications. Due to its penchant for demanding applications, AlTiN is recommended for hardened steels, hardened stainless, tool steels, titanium alloys, and aerospace materials. These applications often create high levels of heat that AlTiN Nano was designed to combat.

altin nano tool coating

Harvey Tool 843508-C6

harvey tool coating zoomed in

Tool Coatings for Non-Ferrous and Non-Metallic Materials

TiB2

TiB2, or Titanium Diboride (-C8), is Harvey Tool’s “bread and butter” coating for non-abrasive aluminum alloys and magnesium alloys, as it has an extremely low affinity to aluminum as compared to other coatings. Aluminum creates lower working temperatures than ferrous materials, so this coating has a max working temperature of of a suitable 900 °F. TiB2 prevents built-up edge and chip packing, further extending its impressive tool life. TiB2 is not recommended for abrasive materials as the carbide is slightly weakened during the coating process. These materials can cause micro fractures that may damage the tool at high RPMs.

TiB2 can be found on a wide variety of Harvey Tool 2 and 3 flute tools as the premium option for high performance in aluminum alloys.

tib2 tool coating

Harvey Tool 820654-C8

ZrN

ZrN, or Zirconium Nitride (-C7), is a general-purpose coating for a wide variety of non-ferrous materials, including abrasive aluminum alloys. This tool coating is a lower cost alternative to diamond coatings, while still boasting impressive performance through its high hardness levels and overall abrasion resistance. ZrN has a max working temperature of 1,110 °F with strong lubricity in abrasive alloys. This coating is best suited for abrasives, such as brass, bronze, and copper, as well as abrasive aluminum alloys that should not be used with TiB2.

zrn tool coating

Harvey Tool 27912-C7

CVD Diamond Tool Coatings

CVD Diamond, or Crystalline CVD Diamond, is a process where the coating is grown directly onto the carbide end mill. This process dramatically improves hardness over other coatings, improving tool life and abrasion resistance while also allowing for higher feed rates. The trade-off for increased wear resistance is a slight rounding of the cutting edge due to the coating application. Due to its increased wear resistance, CVD is best suited for highly abrasive materials such as graphite, composites, green carbide, and green ceramics. Similarly, these tool coatings have a max working temperature of 1,100 °F, meaning they are not well suited for ferrous applications.

Harvey Tool’s CVD Diamond Coating Options:

diamond tool coatings
Amorphous, CVD 4 μm, CVD 9 μm, PCD Diamond

CVD Diamond (4 μm)

The 4 μm is thinner than the 9 μm allowing for a sharper cutting edge, which in effect leaves a smoother finish.

CVD Diamond 9 μm)

The 9 μm CVD tool coating offers improved wear resistance over the 4 μm CVD and Amorphous coatings due to its increased coating thickness.

Amorphous Diamond

Amorphous Diamond (-C4) is a PVD diamond coating which creates an exceptionally sharp edge as compared to CVD. This coating aids in performance and finish in abrasive non-ferrous applications, as it allows for greatly improved abrasion resistance during machining, while still maintaining a sharp cutting edge necessary for certain abrasives. Due to the thinness of the coating, edge rounding is prevented in relation to CVD diamond tooling. Amorphous Diamond is best suited for use in abrasive plastics, graphite, and carbon fiber, as well as aluminum and aluminum alloys with high silica content, due to their abrasiveness. The max working temp is only 750 °F, so it is not suited for use in ferrous machining applications.2

Harvey Tool 809362-C4

PCD Diamond

PCD Diamond, or Polycrystalline Diamond, is a tool coating that is brazed onto the carbide body. In comparison to the other diamond coatings, PCD does not face the same challenges of other coatings as it pertains to rounded cutting edges, as these edges are ground sharp. PCD has the edge benefits of Amorphous Diamond with the abrasion resistance of CVD Diamond. PCD is the thickest diamond layer offered by Harvey Tool, and excels due to its incredible hardness and abrasion resistance. This tool is best suited for all forms of abrasive, non-ferrous materials including abrasive plastics, graphite, carbon fiber, and composites. Similar to the other non-ferrous tool coatings, PCD is not suited for ferrous applications due to its working temperature of 1,100 °F.

pcd diamond

Harvey Tool 12120

Tool Coating Summary

When deciding on a coating for your application there are many factors to be considered. Different coatings often cross several applications with performance trade-offs between all of them. Harvey Tool offers a “Material Specific Selection” that allows users to choose tooling based upon what materials they are working with. Further, Harvey Tool’s technical team is always a phone call away to help in finding the right tool for your specific applications at 1-800-645-5609. Also, you can contact Harvey Tool via e-mail.

Octane Workholding – Featured Customer

Located in Danville, Pennsylvania, Octane Workholding has a long history spanning back to 40 years. This family business started in the 1980s, welding farm equipment and doing general repairs. As time went on, Octane Workholding began shifting toward building bespoke equipment. As the equipment became more complex, machining became a larger part of their business, starting with manual machines and working towards CNC machining. They started to realize the amount of knowledge that they would need to learn to master CNC machining. After machining thousands of parts and gaining experience, they learned what tools were needed to succeed as Machinists and started their journey. They developed value-added products for their own use that are now available for everyone and provide educational materials that are aimed at lessening the steep learning curve of this trade.

Octane Workholding has dedicated years to mastering their CNC abilities. We were able to get in touch with Derek Pulsifer, President of Octane Workholding, to discuss how they got started, current business, and so much more!

How did you get started with Octane Workholding?

Basically, I grew up in our family shop but did not start working full time until after college. Things were heavily fabrication-oriented with only a few manual machines. After a few years running manuals myself, it was decided we would go the CNC route. Teaching myself to be a Machinist was often a struggle with no formal training or peers to reference. Being a family machine shop and working alongside Octane Sr., it could be a lot like an episode of Orange County Choppers. Most of what I share today was learned through thousands of hours of researching and learning the hard way. 

How did you get from welding farm equipment and doing repairs, to manufacturing workholding setups?

Like many things in life, things progressed and customers’ needs shifted. Our fabrication shop has built a lot of equipment for the food, pharmaceutical, and power generation industries for several years. As we gained more customers, things slowly shifted toward more job shop-oriented work. Jobshop work is a surefire way to gain experience quickly. As a Machinist, there were many times I went in search of a solution for common problems we faced. After finding solutions that didn’t fit us, I designed the products we now make today. Thousands of unique parts and decades of experience later, we knew what shops like us were probably encountering as well. Octane Workholding was created to provide solutions to common machining problems. We continue to offer quote-based work to customers through our machine shop in addition to Octane Workholding. We are Craftsmen.

What machines do you currently have in your shop?

We have several manual machines from the classic 1960’s Bridgeport to heavy-duty Cat50 verticals. The machine I actually began on is an old South Bend lathe. Production sawing, Roll Grooving, Shears, Press Brakes, Waterjet Cutting, Welding, and Rolling machines. We also have various new CNC machinery from lathes to verticals. 

What CAM/CAD softwares do you currently use?

I program with both Mastercam and Solidworks. We use Autocad products for 2D applications like Waterjet Cutting. The advent of Fusion 360 has really benefited the industry by bringing affordable software to everyone. I would like to experiment with more CAD/CAM systems to help those who come to us with specific programming questions related to Fusion 360 etc.

What materials are you most often working with?

We primarily work with stainless steel, but no material is too difficult to work with. Materials and SFM are a bit like speed limits on the road, Hastelloy is like a 25 MPH zone, and Aluminum is like the Autobahn. Superalloys require patience and the right recipe.

What sets Octane Workholding apart from the rest of the competition?

I think people appreciate honest companies that actually engage with their customers.  Treating every customer with the same respect, no matter the size of their company. Social media has made helping anyone that needs it, a message away. Whether individuals buy our products or not, we believe the whole industry benefits from the freely available educational materials.

Can you talk about the coolest/most interesting project you have worked on?

We do a lot of neat work but one project especially was great to work on. It is also one of the few that can be made public. Making 11.00″ Custom Scissors for the first time. These Scissors quickly became an obsession once work began on them. Programming them was the first step. Machining them without creating time-consuming custom fixtures was the next challenge. Once they were machined the real fun began.

Having never made Scissors or Knives professionally, I knew the next part would be a learning experience. After ordering some fine grit belts for our sanders, the polishing and sharpening had begun. To begin, I went about polishing the handles and rough sharpening to establish a reference edge on the blades.

Having some paper on hand it was time to give them a try. Success, they cut paper! Now for the real test, they were being created to cut plastic bags. Dread started to creep in as the first cut simply folded the bag in half. This was not good. Ok, what is wrong here? These feel razor-sharp, but they are paperweights at this point. Back to the drawing board. After doing some research on the great UK makers continuing this art, a hollow grind seemed like the solution.

What do we have that can do a hollow grind? A small wheel will put a deep radius if brought back to the blade. I have to make a large wheel so the hollow grind can be shallow. I’ve got it, a faceplate adapter mounted to the Old South Bend, some sandpaper glued to the outside should work! So it began, the journey into learning to hollow grind.

After hours of making things worse and worse, I cannot bring the grind from edge to edge smoothly. Some more research and it seems the technique is to “turn the key”. Wow, it feels unnatural but it works! Finally, a successful hollow grind is performed.

Now for the real art of Scissormaking, the Putter- (fine Scissor Craftsmen which I am not) must sharpen and skillfully assemble them. The final act is to bow the blades carefully such that the edges intersect. They must meet perfectly along the length of the blade as they cross.

One more test, they cut the plastic bag as it passed right through it. This was one of the best moments in my career as a Machinist.

What are your current product offerings?

Our best-selling product is our t-slot cover, The Octane Chip Guard. We also currently offer mounts that offset your Renishaw Tool Setter. Table space is a premium for any milling machine. When the Tool Setter is outside the work envelope, additional work holding or parts can be placed. 

We also offer a T-Slot Drop in Workstop, our drop in workstops can be added at any time, even when access to the end of the t-slot is blocked. This adds a lot of flexibility to set up parts, especially if you forgot to add them beforehand (has happened more than I care to admit). There are a lot of products waiting to be released, but the demand for our t-slot covers has taken priority for now.

Having machined thousands of parts with unique setups, a product that enabled quick changeovers was essential. Cleaning a t-slot is a job Machinists have dreaded for a very long time.  Being silicone, it is extremely easy to trim a piece to fit any setup. Setting up a job for production requires only a few extra minutes to place our t-slot covers. One big problem with vertical machining centers is chip evacuation. Not only does covering the t-slot prevent chips from ever entering the groove, but it actually promotes flushing of every corner of sheet metal. Flood coolant normally is trapped within the grooves, which prevents any chance of the chips being evacuated. Unattended operation is always the goal with any CNC machine, our Chip Guard allows an operator to open the doors to a clean machine. In-process chip fans or automatic washdowns are possible. Safety is also a big issue for any shop. Most Machinists have encountered a chip ricocheting from the t-slots back at their eyes. The color options add a sleek look to any machine. We also offer black for an incognito approach.

Why is high quality tool performance important to you?

Manufacturing is all about process reliability. You may save a few dollars on a tool, but end up paying dividends when said tool fails unexpectedly. A quality tool that increases performance or extends unattended operation, is critical.

Can you talk about a time that Harvey Tool or Helical products really came through and helped you?

Aside from Harvey having tools available as standard, which would be a custom item for the majority of companies. We buy chamfer mills regularly for finishing bevels. The angle being accurate is paramount for finishing. If the angle is off at all, a step can be felt on the finished face. Being confident that a tool that is programmed to cut a feature is accurate, saves us a lot of time. We also rough some heavy stainless steel beveled rings. The heavy chips accumulate due to the 2.00” length of cut., so the solution to this problem was the following chipbreaker endmill – 5 FLUTE, CORNER RADIUS – CHIPBREAKER ROUGHER, VARIABLE PITCH (APLUS).  We are all familiar with the corncob style roughing endmills, which actually create chips that are too small, causing those chips to end up getting into the coolant tank. Helical chipbreaker endmills create a swarf that is the perfect size, as it fits neatly into a container for recycling. The other added benefit is tool life. The bevel rings tend to trap the swarf inside themselves, which can lead to recutting chips that were destroying tool life. The chips were able to be evacuated easily which lead to a 4x’s increase in tool life and a process we could walk away from confidently.

We noticed the education section on your website, not too many companies will add these sections, why do you feel it is important to spread knowledge?

The world saw more technological advancement in 100 years than in all recorded history through manufacturing.  While I may not be part of the next great advancement for humanity, perhaps teaching an aspiring Engineer, will lead to one. Providing the tools for brilliant individuals to go out and make an idea a reality, is something we are committed to. Future generations need to understand how critical manufacturing is to our way of life. 

If you could give one piece of advice to a new machinist ready to take the #PlungeIntoMachining, what would it be?

Learn cad/cam first. Watching YouTube tutorials and educational content likes ours can help accelerate the learning curve. Becoming proficient as a programmer and designer can lead to higher starting salaries. If you can walk into a shop with some knowledge of programming, you may bypass a lot of the red tape companies might present to a new employee. Machining is often the easiest part, work holding and programming are often the biggest hurdles. Not everything has been invented yet, perhaps your niche will be making ornate pens, flashlights, knives, firearm parts, etc., creative designs are always in demand. Many successful businesses started in a garage with a hobby machine. Designing your own products can lead to a booming business that can sustain your family and eventually your employees’ families. 

Is there anything else you would like to share with the In The Loupe community?

We are adding more and more educational material to our website.  It’s definitely worth bookmarking for anyone interested in learning more about this trade.

  • Speeds and feeds for turning, drilling, surface finish charts, etc.
  • Threading data like you would find in the Machinist’s handbook, but easier to find and read.
  • Educational articles on topics like quoting, lathe education, mill education etc.
  • Fun DIY projects you can make, like a tap follower.
  • Programming examples and curriculum are in progress with more information being added.

To learn more about Octane Workholding find their website here. Also, you can follow them on Instagram @octane_workholding.

The 3 Critical Factors of Turning Speeds and Feeds

Many factors come into play when determining a proper turning speeds and feeds and depth of cut strategy for turning operations. While three of these factors – the ones we deemed to be among the most critical – are listed below, please note that there are many other considerations that are not listed, but that are also important. For instance, safety should always be the main focus of any machining operation, as improper cutting tool parameters can test a machine’s limits, resulting in an accident that can potentially cause significant bodily harm.

Machine condition, type, capabilities, and set-up are all significantly important to an overall successful turning operation, as is turning tool and holder selection.

Turning Speeds and Feeds Factor 1: Machine Condition

The condition of your machine should always be considered prior to beginning a machining operation on a lathe. Older machines that have been used for production operations where hard or abrasive materials are machined tend to have a large amount of backlash, or wear, on the machine’s mechanical parts. This can cause it to produce less than optimal result and may require that a tooling manufacturer’s recommended speeds and feeds parameters need to be dialed back a bit, as to not run the machine more aggressively than it can handle.

turning speeds and feeds

Factor 2: Machine Type and Capabilities

Before dialing in turning speeds and feeds, one must understand their machine type and its capabilities. Machines are programmed differently, depending on the type of turning center being used: CNC Lathe or Manual Lathe.

CNC Lathe Turning Centers

With this type of machine, the part and tool have the ability to be set in motion.

CNC lathe turning centers can be programmed as a G96 (constant surface footage) or G97 (constant RPM). With this type of machine, the maximum allowable RPM can be programmed using a G50 with an S command. For example, inputting a G50 S3000 into your CNC program would limit the maximum RPM to 3,000. Further, with CNC Lathe Turning Centers, the feed rate is programmable and can be changed at different positions or locations within a part program.

Manual Lathe Turning Centers

With this type of machine, only the part is in motion, while the tool remains immobile.

For manual lathe turning centers, parameters are programmed a bit differently. Here, the spindle speed is set at a constant RPM, and normally remains unchanged throughout the machining operation. Obviously, this puts more onus on a machinist to get speed correct, as an operation can quickly be derailed if RPM parameters are not optimal for a job. Like with CNC lathe turning centers, though, understanding your machine’s horsepower and maximum feed rate is critical.

Factor 3: Machine Set-Up

turning speeds and feeds proper tool setup
Excessive Tool Stickout. Digital Image, Hass Automation. https://www.haascnc.com/service/troubleshooting-and-how-to/troubleshooting/lathe-chatter—troubleshooting.html

Machining Conditions

When factoring in your machine set-up, machining conditions must be considered. Below are some ideal conditions to strive for, as well as some suboptimal machining conditions to avoid for dialing in proper turning speeds and feeds.

Ideal Machining Conditions for Turning Applications

  • The workpiece clamping or fixture is in optimal condition, and the workpiece overhang is minimized to improve rigidity.
  • Coolant delivery systems are in place to aid in the evacuation of chips from a part and help control heat generation.

Suboptimal Machining Conditions for Turning Applications

  • Utilizing turning tools that are extended for reach purposes, when not necessary, causing an increased amount of tool deflection and sacrificing the rigidity of the machining operations.
  • The workpiece clamping or fixturing is aged, ineffective, and in poor condition.
  • Coolant delivery systems are missing, or are ineffective
  • Machine does not feature any guarding or enclosures, resulting in safety concerns.

Cutting Tool & Tool Holder Selection

As is always the case, cutting tool and tool holder selection are pivotal. Not all turning tool manufacturers are the same, either. The best machinists develop longstanding relationships with tooling manufacturers, and are able to depend on their input and recommendations. Micro 100, for example, has manufactured the industry’s highest quality turning tools for more than 50 years. Further, its tool holder offering includes multiple unique styles, allowing machinists to determine the product that’s best for them.

lathe tool holder
Pro Tip: Be sure to take into consideration the machine’s horsepower and maximum feed rate when determining running parameters.

Bonus: Common Turning Speeds and Feeds Application Terminology

Vc= Cutting Speed

n= Spindle Speed

Ap=Depth of Cut

Q= Metal Removal Rate

G94 Feedrate IPM (Inches Per Minute)

G95 Feedrate IPR (Inches Per Revolution)

G96 CSS (Constant Surface Speed)

G97 Constant RPM (Revolutions Per Minute)

R & S Machining – Featured Customer

Featured Image Courtesy of R & S Machining

Located in St. Louis, Missouri, R & S Machining specializes in 4 & 5 axis machining and manufacturing of aerospace components. Since R & S was founded in 1992, they have instilled a spirit of hard work and determination to exceed customer expectations. Equipped with up-to-date machines and automation, R & S Machining has high-quality equipment to keep them as efficient as possible to stay ahead of the competition. The highly skilled men and women operating the manufacturing facility are committed to a high quality standard to meet all customer requirements. Because of this commitment, R & S Machining has been able to expand its facilities in the past four years by more than 225,000 square feet.

We were able to get in touch with Matthew Roderick, the lead programmer for R & S Machining. Matthew took some time out of his busy schedule to answer some questions about R & S Machining, and how the company continues to grow.

Photo Courtesy of: R & S Machining

Can you tell us a little about R & S Machining?

R & S Machining is dedicated to continual improvement and growth. We strive to buy very high quality machines and tooling. We also equip most of our machines with automation. Whether it is a bar feeder, pallet changer, FMS, or robot, nearly all our machines have some form of automation to increase our lights out production. In the past 4 years, we have built a new facility and purchased a new facility. We have grown by more than 225,000 square feet and 35 employees in this timespan. With the backing of our ownership, continued success and relationships with our customers, very dedicated employees, and high-quality reliable manufacturing equipment, we are in a league of our own and continue to strive towards our goal of becoming the powerhouse manufacturing company of the Midwest.

R & S Machining currently uses Hermie, Okuma, Makino, and Kenichi machines in the facility, while utilizing CAM/CAD software such as Siemens NX, Catia, and Mastercam.

How did R & S get into Aerospace and Defense Manufacturing?

Our president worked at Boeing for 10 years. When he left to start his own company, we were given an opportunity with the Boeing Company to manufacture aerospace and defense components based on the quality of work that our President produced during his time with them. We continued to produce high quality products with an emphasis on on-time delivery and the rest is history.

Photo Courtesy of: R & S Machining

What sets R & S apart from the rest of the competitors?

We take on all the work that our competitors no quote or refuse to do. The complexity of parts that flow through this shop is like no other place. We believe there is no other company that can produce the complexity level of parts that we make in the time frames we are given by our customers.

Customer satisfaction is maintained through effectively applying the quality system. Continued training and process review enable R & S Machining to meet customers’ ever-changing requirements. 

What is your favorite project you have had come through the shop?

We manufacture Inlet Ducts for a variety of Fighter Jets. The complexity of these parts is unmatched and the creativity in programming the parts in the CAM system has to be at its peak. Some of these parts require programs of 600+ toolpaths with a majority of them being full 5axis simultaneous paths. Then, when you get to see the machine throwing a 1,100 pound block around like it’s nothing at 2000 IPM in full 5axis simultaneous motion, it’s pretty humbling.

Photo Courtesy of: R & S Machining

What is your connection with the Missouri SkillsUSA Competition?

SkillsUSA is a nonprofit national education association that serves middle school, high school, and college/postsecondary students preparing for careers in trade, technical, and skilled service (including health) occupations. SkillsUSA’s mission is to empower its members to become world class workers, leaders, and responsible American citizens. It emphasizes total quality at work—high ethical standards, superior work skills, lifelong education, and pride in the dignity of work.

Over the past 4 years, we have had many of our employees participate and win in the competition. We have had 5 employees win the district championship, 5 employees win the state championship, and 3 employees win the national championship.

Photo Courtesy of: R & S Machining

Why is high quality tool performance important to you?

We rely on high quality tool performance to meet the tolerancing demands of our customers. Our tolerances range from hole tolerances of +.002″/-.001″, thickness tolerances of +-.01″, profile tolerances of .03″, critical hole tolerances of +-.0002″, and critical hole true position tolerances of .007″. We also rely heavily on lights-out run time overnight, so having a high quality tool that you know is still going to be cutting effectively in the morning and throughout the night is critical to our operation.

We had a 50+ quantity stainless steel job that we were only getting 2-3 parts per tool using tools from a different manufacturer. We changed our tool to a Helical endmill and left everything else the same and made over 30 parts before having to change out the tool.

Photo Courtesy of: R & S Machining

If you could give one piece of advice to a new machinist ready to take the #PlungeIntoMachining, what would it be?

There are tons of cool and flashy things out there, but you can not skip the fundamentals. They are the building block to your entire career and they are the concepts you will use every single day. Use the technology to further your skills, not the basis of your skills. At the end of the day, you always have to know feeds and speeds, depth of cuts, work holding, and what you can get away with.

Is there anything else you would like to share with the In The Loupe community?

Helical tooling is unmatched in the HEM hard metal category. These tools have changed the way we manufacture parts and give us the confidence we need to accomplish our high precision and complex parts.

If you want to see what is next for R & S Machining or reach out and ask them some questions, you can follow them on Instagram @randsmachine.

The Secret Mechanics of High Feed End Mills

A High Feed End Mill is a type of High-Efficiency Milling (HEM) tool with a specialized end profile that allows the tool to utilize chip thinning to have dramatically increased feed rates. These tools are meant to operate with an extremely low axial depth so that the cutting action takes place along the curved edge of the bottom profile. This allows for a few different phenomena to occur:

  • The low lead angle causes most of the cutting force to be transferred axially back into the spindle. This amounts to less deflection, as there is much less radial force pushing the cutter off its center axis.
  • The extended curved profile of the bottom edge causes a chip thinning effect that allows for aggressive feed rates.

The Low Lead Angle of a High Feed End Mill

As seen in Figure 1 below, when a High Feed End Mill is properly engaged in a workpiece, the low lead angle, combined with a low axial depth of cut, transfers the majority of the cutting force upward along the center axis of the tool. A low amount of radial force allows for longer reaches to be employed without the adverse effects of chatter, which will lead to tool failure. This is beneficial for applications that require a low amount of radial force, such as machining thin walls or contouring deep pockets.

high feed mill roughing
Figure 1: Isometric view of a feed mill engaged in a straight roughing pass (left), A snapshot front-facing view of this cut (right)

Feed Mills Have Aggressive Feed Rates

Figure 1 also depicts an instantaneous snapshot of the chip being formed when engaged in a proper roughing tool path. Notice how the chip (marked by diagonal lines) thins as it approaches the center axis of the tool. This is due to the curved geometry of the bottom edge. Because of this chip thinning phenomenon, the feed of the tool must be increased so that the tool is actively engaged in cutting and does not rub against the workpiece. Rubbing will increase friction, which in turn raises the level of heat around the cutting zone and causes premature tool wear. Because this tool requires an increased chip load to maintain a viable cutting edge, the tool has been given the name “High Feed Mill.”

high feed end mill ad

Other Phenomena Due to Curved Geometry of Bottom Edge

The curved geometry of the bottom edge also sanctions for the following actions to occur:

  • A programmable radius being added to a CAM tool path
  • Scallops forming during facing operations
  • Different-shaped chips created during slotting applications, compared to HEM roughing

Programmable Radius

Helical Solutions’ High Feed End Mills has a double radius bottom edge design. Because of this, the exact profile cannot be easily programmed by some CAM software. Therefore, a theoretical radius is used to allow for easy integration.  Simply program a bullnose tool path and use the theoretical radius (seen below in Figure 2) from the dimensions table as the corner radius.

high feed mill programmable radius
Figure 2: Programmable radius of a double radius profile tool

Managing Scallops

A scallop is a cusp of material left behind by cutting tools with curved profiles. Three major factors that determine the height and width of scallops are:

  1. Axial Depth of Cut
  2. Radial Depth of Cut
  3. Curvature of Bottom Edge or Lead Angle

Figure 3 below is a depiction of the scallop profile of a typical roughing cut with a 65% radial step over and 4% axial depth of cut. The shaded region represents the scallop that is left behind after 2 roughing passes and runs parallel to the tool path.

roughing cut scallop profile
Figure 3: Back view of roughing cut with a 65% radial step over

Figures 4 and 5 show the effects of radial and axial depth of cuts on the height and width of scallops. These figures should be viewed in the context of Figure 3. Percentage by diameter is used rather than standard units of measurement to show that this effect can be predicted at any tool size. Figure 4 shows that a scallop begins to form when the tool is programmed to have a radial step over between 35% and 40%. The height increases exponentially until it is maximized at the axial depth of cut. Figure 5 shows that there is a linear relationship between the radial step over and scallop width. No relationship is seen between scallop width and axial depth of cut as long as ADOC and the radius of curvature of the bottom cutting edge remains consistent.

graph of scallop height versus depth of cut
Figure 4: Graph of Scallop Height vs. Depth of Cut
graph of scallop width versus depth of cut
Figure 5: Scallop Width vs. Depth of Cut

From the graphs in Figures 4 and 5 we get the following equations for scallop dimensions.

Notes regarding these equations:

  • These equations are only applicable for Helical Solutions High Feed End Mills
  • These equations are approximations
  • Scallop height equation is inaccurate after the axial depth of cut is reached
  • RDOC is in terms of diameter percentage (.55 x Diameter, .65 x Diameter, etc…)

Shop Helical Solutions’ Fully Stock Selection of High Feed End Mills

Curvature of the Bottom Edge of High Feed End Mills

The smaller the radius of curvature, the larger the height of the scallop. For example, the large partial radius of the Helical Solutions High Feed End Mill bottom cutting edge will leave a smaller scallop when compared to a ball end mill programmed with the same tool path. Figure 6 shows a side by side comparison of a ball end mill and high feed mill with the same radial and axial depth of cut. The scallop width and height are noticeably greater for the ball end mill because it has a smaller radius of curvature.

feed mill versus ball end mill
Figure 6: Scallop diagram of High Feed Mill and Ball End Mill with the same workpiece engagement

Full Slotting

When slotting, the feed rate should be greatly reduced relative to roughing as a greater portion of the bottom cutting edge is engaged. As shown in Figure 7, the axial step down does not equate to the axial engagement. Once engaged in a full slot, the chip becomes a complex shape. When viewing the chip from the side, you can see that the tool is not cutting the entirety of the axial engagement at one point in time. The chip follows the contour on the slot cut in the form of the bottom edge of the tool. Because of this phenomenon, the chip dips down to the lowest point of the slot and then back up to the highest point of axial engagement along the side. This creates a long thin chip that can clog up the small flute valleys of the tool, leading to premature tool failure. This can be solved by decreasing the feed rate and increasing the amount of coolant used in the operation.

high feed mill chip formation
Figure 7: Formation of a chip when a feed mill is engaged in a full slotting operation.

In summary, the curved profile of the bottom edge of the tool allows for higher feed rates when high feed milling, because of the chipping thinning effect it creates with its low lead angle. This low lead angle also distributes cutting forces axially rather than radially, reducing the amount of chatter that a normal end mill might experience under the same conditions. Machinists must be careful though as the curved bottom edge also allows for the formation of scallops, requires a programmable radius when using some CAM packages, and make slotting not nearly as productive as roughing operations.

Causes & Effects of Built-Up Edge (BUE) in Turning Applications

In turning operations, the tool is stationary while the workpiece is rotating in a clamped chuck or a collet holder. Many operations are performed in a lathe, such as facing, drilling, grooving, threading, and cut-off applications. it is imperative to use the proper tool geometry and cutting parameters for the material type that is being machined. If these parameters are not applied correctly in your turning operations, built-up edge (BUE), or many other failure modes, may occur. These failure modes adversely affect the performance of the cutting tool and may lead to an overall scrapped part.

When inspecting a cutting tool under a microscope or eye loupe, there are several different types of turning tool failure modes that can be apparent. Some of the most common modes are:

  • Normal Flank Wear: The only acceptable form of tool wear, caused by the normal aging of a used cutting tool and found on the cutting edges.
    • This abrasive wear, caused by hard constituents in the workpiece material, is the only preferred method of tool wear, as it’s predictable and will continue to provide stable tool life, allowing for further optimization and increased productivity.
  • Cratering: Deformations found on the cutting face of a tool.
    • This tool mode is a chemical and heat failure, localized on the rake face area of the turning tool, or insert. This failure results from the chemical reaction between the workpiece material and the cutting tool and is amplified by cutting speed. Excessive Crater Wear weakens a turning tool’s cutting edge and may lead to cutting edge failure.
  • Chipping: Breaking of the turning tool along its cutting face, resulting in an inaccurate, rough cutting edge.
    • This is a mechanical failure, common in interrupted cutting or non-rigid machining setups. Many culprits can be to blame for chipping, including machine mishaps and tool holder security.
  • Thermal Mechanical Failure (Thermal Cracking): The cracking of a cutting tool due to significant swings in machining temperature.
    • When turning, heat management is key. Too little or too much heat can create issues, as can significant, fast swings in temperature (repeated heating and cooling on the cutting edge). Thermal Mechanical Failure usually shows in the form of evenly spaced cracks, perpendicular to the cutting edge of the turning tool.
  • Built-Up Edge (BUE): When chips adhere to the cutting tool due to high heat, pressure, and friction.

Effects of Built-Up Edge in Turning Application

A built-up edge is perhaps the easiest mode of tool wear to identify, as it may be visible without the need for a microscope or an eye loupe. The term built-up edge means that the material that you’re machining is being pressure welded to the cutting tool. When inspecting your tool, evidence of a BUE problem is material on the rake face or flank face of the cutting tool.

built up cutting edge on turning tools
Image Source: Carbide inserts Wear Failure modes. | machining4.eu, 2020

This condition can create a lot of problems with your machining operations, such as poor tool life, subpar surface finish, size variations, and many other quality issues. The reason for these issues is that the centerline distance and the tool geometry of the cutting edge are being altered by the material that’s been welded to the rake or flank face of the tool. As the BUE condition worsens, you may experience other types of failures or even catastrophic failure.                     

Causes of Built-Up Edge in Turning Applications

Improper Tooling Choice

Built-Up Edge is oftentimes caused by using a turning tool that does not have the correct geometry for the material being machined. Most notably, when machining a gummy material such as aluminum or titanium, your best bet is to use tooling with extremely sharp cutting edges, free cutting geometry, and a polished flank and rake face. This will not only help you to cut the material swiftly but also to keep it from sticking to the cutting tool.

various turning tools

Using Aged Tooling

Even when using a turning tool with correct geometry, you may still experience BUE. As the tool starts to wear and its edge starts to degrade, the material will start building up on the surface of the tool. For this reason, it is very important to inspect the cutting edge of a tool after you have machined a few parts, and then randomly throughout the set tool life. This will help you identify the root cause of any of the failure modes by identifying them early on.

Insufficient Heat Generation

Built-up edge can be caused from running a tool at incorrect cutting parameters. Usually, when BUE is an issue, it’s due to the speed or feed rates being too low. Heat generation is key during any machining application – while too much heat can impact a part material, too little can cause the tool to be less effective at efficiently removing chips.

4 Simple Ways to Mitigate BUE in Turning Applications

  1. When selecting a tool, opt for free cutting, up sharp geometries with highly polished surfaces. Selecting a tool with chipbreaker geometry will also help to divide chips, which will help to remove it from the part and the cutting surface.
  2. Be confident in your application approach and your running parameters. It’s always important to double-check that your running parameters are appropriate for your turning application.
  3. Make sure the coolant is focused on the cutting edge and increase the coolant concentration amount.
  4. Opt for a coated Insert, as coatings are specifically engineered for a given set of part materials, and are designed to prevent common machining woes.
solid carbide turning tool

Achieving Success in CNC Woodworking

Developing a Successful Cutting Direction Strategy

There are a number of factors that can affect the machining practices of wood in woodworking. One that comes up a lot for certain hardwoods is the cutting direction, specifically in relation to the grain pattern of the wood. Wood is an anisotropic material. This means that different material properties are exhibited in different cutting directions. In terms of lumber, there are different structural grades of wood related to grain orientation. If the average direction of the cellulose fibers are parallel to the sides of the piece of lumber, then the grains are said to be straight. Any deviation from this parallel line and the board is considered to be “cross-grain”. Figure 1 below depicts a mostly straight grain board with arrows indicating the different axes. Each of these axes exhibits different sets of mechanical properties. Because of these differences, one must be conscious of the tool path in woodworking and minimize the amount of cutting forces placed on the cutter in order to maximize its tool life.

straight grain wood board with woodworking axes
Figure 1: Mostly straight grain board with arrows indicating different axes

Cutting perpendicular to the grain is known as cutting “across the grain” in woodworking. In Figure 1 above, this would be considered cutting in the radial or tangential direction. Cutting parallel to the grain is known as cutting “along the grain” (longitudinally in terms of Figure 1). The closer you are to cutting at 90° to the grain of the wood in any direction, the larger the cutting force will be. For example, a tool with its center axis parallel to the tangential direction and a tool path along the longitudinal direction would have less wear than a tool with the same center axis but moving in the radial direction. The second type of tool orientation is cutting across more grain boundaries and therefore yields greater cutting forces. However, you must be careful when cutting along the grain as this can cause tear-outs and lead to a poor surface finish.

The Proper Formation of Wood Chips With CNC Woodworking

When cutting wood parallel to the grain, there are three basic types of chips that are formed. When cutting perpendicular to the grain, the chip types generally fall into these same 3 categories, but with much more variability due to the wide range in wood properties with respect to the grain direction.

Type 1 Chips

Type 1 chips are formed when wood splits ahead of the cutting edge through cleavage until failure in bending occurs as a cantilever beam. A large force perpendicular to the shear plane is produced, causing the wood ahead of the cutting edge to split, forming this tiny cantilever beam. When the upward force finally exceeds the strength of this tiny beam, it breaks off.  These types of chips cause comparatively little wear compared to types 2 and 3, as the material is splitting before coming in contact with the pointed edge. End mills with either extremely high rake or very low rake angles often produce type 1 chips. This is especially true when machining against grain slopes that are greater than 25°. Woods with moisture content less than 8%form discontinuous chips and are at a higher risk of tear-out.

Type 2 Chips

Type 2 chips are the most desirable of the three types in terms of surface finish. They are a result of material failure along a diagonal shear plane, extending from the cutting edge to the workpiece surface. Type 2 chips form when there is a proper balance between the properties of the wood, cutting parameters, and cutter geometry. Woods with a moisture content between 8% and 20%have a much higher chance of forming continuous type 2 chips while leaving a good surface finish.

Type 3 Chips

The last type of chip forms when the rake angle of a cutter is much too low. In this scenario, the cutting force is almost parallel to the direction of travel. This causes a soft material, such as wood, to be crushed rather than sheared away, leaving a poor surface finish. Generally, the surface left behind looks like tiny bundles of wood elements, a surface defect commonly known as “fuzzy grain.” This type of chip occurs more frequently in softwoods as the crushing situation is compounded in low-density woods.

types of wood chips in woodworking
Figure 2: Different types of wooden chips

Extending Tool Life When Woodworking

Speeds & Feeds Rules of Thumb

There are several different categories of tool wear that occur when cnc woodworking. General rules of machining still apply as RPM has the greatest influence on wear rate. Over-feeding can increase tool wear exponentially and also cause tool breakage. As with most machining operations, a balance between these two is essential. If you are looking to increase your productivity by increasing your speed, you must increase your feed proportionally in order to maintain a balance that keeps the tool properly engaged in the material.

Proper Management of Heat

When cutting tools are exposed to high heat, they begin to wear even faster, due to corrosion. The cobalt binder within most carbide tools on the market begins to oxidize and break free of the cutting edge. This sets off a chain reaction, as when the binder is removed, the tungsten carbide breaks away, too. Different species of wood and types of engineered wood have different corrosive behaviors at high temperatures. This is the most consistent type of wear that is observed when machining MDF or particleboard. The wear is due to the chlorine and sulfate salts found in adhesives as this accelerates high-temperature corrosion.  As with aluminum, when the silica content of a wood increases, so too does its corrosiveness.

Generally, increased tool wear is observed in wood with high moisture content. This trait is due to the increased electro-chemical wear caused by the extractives in wood., Moisture content in wood includes substances such as resins, sugars, oils, starches, alkaloids, and tannins in the presence of water. These molecules react with the metallic constitutes of the cutting tool and can dull the cutting edge. Carbide is more resistant to this type of wear compared to high-speed steel.

Best Coatings for Extended Tool Life in Wood

If you want a longer-lasting tool that will maintain its sharp cutting edge (and who doesn’t), you may want to consider an Amorphous Diamond coating. This is an extremely abrasive resistant coating meant for non-ferrous operations in which the temperature of the cutting zone does not exceed 750 °F. This coating type is one of Harvey Tool’s thinnest coatings, therefore minimizing the risk of any edge rounding and maximizing this edge’s durability.

Avoiding Common Woodworking Mishaps

Tear Out

Tear out, sometimes called chipped grain or splintering, is when a chunk of the wood material being machined tears away from the main workpiece and leaves an unappealing defect where it used to be. This is one of the most common defects when machining wood products. There are many different reasons that tear out occurs. Material characteristics are something to be considered. Tear out is more likely to occur if the grain orientation is less than 20°relative to the tool path, the moisture content of the wood is too low, or the density of the wood is too low. Figure 4 shows the grain orientation angle relative to the tool path. In terms of machining parameters, it can also occur if either the chip load, depth of cut, or rake angle is too high.

woodworking grain in relation to tool path
Figure 4: Example of grain orientation angle relative to the tool path

Fuzzy Grain Finish

Fuzzy grain looks like small clumps of wood attached to the newly machined face and occurs when the wood fibers are not severed properly. Low rake or dull cutting tools indent fibers until they tear out from their natural pattern inside, causing type 3 chips to form, resulting in a poor finish. This can be exacerbated by a low feed or depth of cut as the tool is not properly engaged and is plowing material rather than shearing it properly. Softer woods with smaller and lesser amounts of grains are more susceptible to this type of defect. Juvenile wood is known to be particularly liable for fuzzy grain because of its high moisture content.

fuzzy grain wood finish
Figure 5: Example of a fuzzy grain finish

Burn Marks

Burn Marks are a defect that is particularly significant in the case of machining wood, as it is not generally a concern when machining other materials. Dwelling in a spot for too long, not engaging enough of the end mill in a cut, or using dull tools creates an excessive amount of heat through friction, which leaves burn marks. Some woods (such as maple or cherry) are more susceptible to burn marks, therefore tool paths for these types should be programmed sensibly. If you are having a lot of trouble with burn marks in a particular operation, you may want to try spraying the end mill with a commercial lubricant or paste wax. Be careful not to use too much as the excess moisture can cause warping. Increasing your tool engagement or decreasing RPM may also combat burn marks.

burn marks from wood cutter
Figure 6: Example of burn marks

Chip Marks

Chip marks are shallow compressions in the surface of the wood that have been sprayed or pressed into the surface. These defects can swell with an increase in moisture content, worsening the finish even more. This type of blemish is generally caused by poor chip evacuation and can usually be fixed by applying air blast coolant to the cutting region during the operation.

Raised Grain

Raised grain, another common defect of woods, is when one or more portions of the workpiece are slightly lower than the rest. This blemish is particularly a problem when machining softer woods with dull tools as the fibers will tear and deform rather than be cleanly sheared away. This effect is intensified when machining with slow feeds and the wood has a high moisture content. Variations in swelling and shrinking between damaged and undamaged sections of wood exacerbate this flaw. It’s for this reason that raised grain is a common sight on weather-beaten woods. Work holding devices that are set too tight also have a chance of causing raised grain.

Differentiating Harvey Tool Wood Cutting & Plastic Cutting End Mills

Machinists oftentimes use Plastic Cutting End Mills for woodworking, as this tool has very similar internal geometries to that of an End Mill for Wood. Both tools have large flute valleys and sharp cutting edges, advantageous for the machining of both plastic and wood. The main difference between the Harvey Tool plastic cutters and the woodcutters is the wedge angle (a combination of the primary relief and rake angle). The woodcutter line has a lower rake but still has a high relief angle to maintain the sharpness of the cutting edge. The lower rake is designed to not be as “grabby” as the plastic cutters can be when woodworking. It was meant to shear wood and leave a quality surface finish by not causing tear-out.

Harvey Tool’s offering of End Mills for Wood includes both upcut and downcut options. The upcut option is designed for milling natural and engineered woods, featuring a 2-flute style and a wedge angle engineered for shearing wood fiber materials without causing tear out or leaving a fuzzy grain finish. The downcut offering is optimized for milling natural and engineered woods and helps prevent lifting on vacuum tables.

For more help on achieving a successful machining operation, or more information on Harvey Tool’s offering of End Mills for Wood, please contact Harvey Tool’s team of engineers at 800-645-5609.

Schon DSGN – Featured Customer

Featured Image Courtesy of Ian Schon, Schon DSGN

In 2012, engineer Ian Schon wanted to put his skill for design to the test. He decided to challenge himself by designing a normal, everyday item: a pen. His goal was to take the pen from the design concept to manufacturing it within his own shop. Ian designed his pen how he thought a pen should be: durable, reliable, compact, leak-proof, and easy to use. Most of all, though, he wanted the pen to be of a superior quality, not something easily lost or thrown away.

With the design concept in place, Ian started his work on engineering and manufacturing his new pen. He made many prototypes, and with each discovered new features and additions to better his design. Today, Ian manufacturers his pens through local fabrications in Massachusetts, using local supplies. He makes them from 6061 Aluminum, unique in that it molds to its users’ hand, over time. His pens are designed to outlast its user and be passed on through generations.

Ian was kind enough to take time out of his busy schedule to answer some questions about his manufacturing success.

Schon DSGN silver wrist watch with black band
Photo Courtesy of: Ian Schon, Schon DSGN

What sets Schon DSGN apart from competition?

I think I have a unique approach to designing and manufacturing. I design things that I like, and make them the way that I want to.  I don’t rush things out the door. I’m not thinking about scale, growth, making a big shop, etc. I just want to live a simple life where I make cool objects, sell them, and have enough time in the week to sneak out into the woods and ride my bike. This ethos takes the pressure off a lot, and that makes the workflow freer without as much stress as I had in my past career as a product development engineer.

This workflow isn’t for everyone. it’s not a winning combo for massive business success, per se, and if you audited me you would tell me I’m holding back by not scaling and hiring, but I like it. I see myself as a hybrid between artist and entrepreneur. I love doing things start to finish, blank paper to finished part on the machine. Owning that entire workflow allows for harmony of engineering, machining, tooling, finishing, R+D, marketing, etc. Further, it ensures that I don’t miss critical inflection points in the process that are ripe for process evolution and innovation, resulting in a better product in the end.

I’m sure the way I do things will change over time, but for now I’m still figuring things out and since I work largely alone (I have one amazing helper right now assisting with assembly, finishing, and shipping) I have lots of flexibility to change things and not get stuck in my ways.

Also, by working alone, I control the music. Key!

schon dsgn turning metal on lathe
Photo Courtesy of: Ian Schon, Schon DSGN

Where did your passion for pens come from?

My friend Mike had a cool pen he got from a local shop and I was like “man I like that,” so I made one with some “improvements.” At the time, in my mind, they were improvements, but I have learned now that they were preferences, really. I made a crappy pen on a lathe at the MIT MITERS shop back in 2010, and that summer I bought a Clausing lathe on craigslist for $300 and some tooling and started figuring it all out. I made a bunch of pens, wrote with them, kept evolving them, and eventually people asked me to make pens for them.  I didn’t really intend to start a business or anything, I just wanted to make cool stuff and use it. Bottle openers, knives, bike frames, etc. I made lots of stuff. Pens just stuck with me and I kept pushing on it as a project for my design portfolio. Eventually it became something bigger. Turns out my pen preferences were shared with other people.

Schon dsgn gold and copper metal pens
Photo Courtesy of: Ian Schon, Schon DSGN

What is the most difficult product you have had to make and why?

Making watch cases – wow. What an awful part to try and make on a desktop Taig 3 axis mill and a Hardinge lathe in my apartment! I started working on machining watch cases in 2012, and I finished my first one in my apartment in 2015 (to be fair, I was working on lots of other stuff during that time! But yeah, years…). What a journey. Taught me a lot. Biting off more than you can chew is a great way to learn something. 

What is the most interesting product you’ve made?

When I worked at Essential Design in Boston I worked on the front end of a Mass Spectrometer. The requirements on the device were wild. We had high voltage, chemical resistance, crazy tolerances, mechanism design, machining, injection molding – truly a little bit of everything! It was a fun challenge that I was fortunate to be a part of. Biomolecule nanoscale analysis device. Try saying that ten times fast.

I have something fountain pen related in the works now that I find more interesting, and very, very complex, but it’s under wraps a bit longer. Stay tuned. 

Schon dsgn gold and copper metal pens
Photo Courtesy of: Ian Schon, Schon DSGN

Who is the most famous contact that you have worked on a project with?

I have made watches for some incredible customers, but I unfortunately cannot talk about who they are. Most of my watch work outside of my own parts is also under NDA which is a bummer, but hey it was great work regardless.

Same thing with the pens. I know that some of my pen are in the touring cases of a few musicians, one of which is in the rock and roll hall of fame. But I have to keep it tight!

Before leaving to work for myself, I was part of a design team at IDEO in Cambridge that designed the new Simplisafe Home Security System. As an engineer and designer, I got listed on the patents. That wasn’t machining and was more design and engineering of injection molded plastic assemblies,  but it was still cool, though! Cutting my teeth in the design industry before machining helps me a lot with the creative process in the workshop. Lots of overlap.

What capabilities does your shop have?

I utilize Citizen L series sliding headstock machines to run my company. These are Swiss Machines (though made in Japan) with twin spindles and have live tooling for milling operations. I got into this type of machining after getting advice from friends in the industry and subcontracting my work to shops with these style of machines for 7 years.

Beyond the Swiss Machines, I have a new Precision Matthews Manual Mill, a Southbend Model A, a Hardinge Cataract Lathe, and a bunch of smaller Derbyshire lathes and mills. Most of these are for maintenance related tasks – quick mods and fixtures and my watchmaking/R&D stuff. I also have a Bantam Tools Desktop CNC machine on the way, a nice machine for quick milled fixtures in aluminum and nonferrous materials. I tested this machine during their development phases and was really impressed.

What CAM/CAD software are you using?

I use Fusion 360 for quick milled stuff, but most of my parts are programmed by hand since the lathe programming for Swiss work can be done without much CAM. I’m sure I could be doing things better on the programming side, but hey, every day I learn something new. Who knows what I’ll be doing a year or two from now?

schon dsgn turning wrist watch on lathe
Photo Courtesy of: Ian Schon, Schon DSGN

What is your favorite material to work with and why?

Brass and Copper. The chips aren’t stringy, it’s easy to cut quickly and the parts have this nice hefty feel to them. Since I make pens, the weight is a big piece of the feeling of a pen. The only downside is I’m constantly figuring out ways to not dent the parts as they are coming off the machines! My brass parts are like tiny brass mallets and they LOVE to get dinged up in the ejection cycles. I ended up making custom parts catchers and modifying the chutes on the machines to navigate this. I might have some conveyors in my future….yeah. Too many projects!

schon dsgn disassembled wrist watch
Photo Courtesy of: Ian Schon, Schon DSGN

Why is high quality tool performance important to you?

It’s not just important, it’s SUPER important. As a solo machinist running my own machines, being able to call a tooling company and get answers on how I should run a tool, adjust its RPM, feed, DOC, or cutting strategy to get a better result is invaluable. I find that as much as I’m paying for tool performance, I’m also paying for expertise, wisdom and answers. Knowing everything is cool and all (and I know some of you out there know everything under the sun), but since I don’t know everything, it’s so nice to be able to pick up a phone and have someone in my corner. These tech support people are so crucial. Being humble and letting support guide me through my tooling challenges has helped me grow a lot. It’s like having a staff of experienced machinists working at my company, for free! Can’t beat that. Micro 100 and Helical have helped me tons with their great support.

schon dsgn multicolored fountain pens
Photo Courtesy of: Ian Schon, Schon DSGN

When was a time that Harvey, Helical or Micro product really came through and helped your business?

The Helical team (shout out to Dalton) helped me nail some machining on some very wild faceted pens I was working on this month. When I switched to Helical, my finishes got crazy good. I just listened to recommendations, bought a bunch of stuff, and kept trying what Dalton told me to. Eventually, that led to a good recipe and manageable tool wear. It was great!

I also like how representatives from the Harvey/Helical/Micro family often cross reference each other and help me find the right solution, regardless of which company I’m getting it from. Nice system.

The quiet hero in my shop is my Micro 100 quick change system. It just works great. Fast to swap tools, easy to setup, cannot argue with it! Too good. 

Schon DSGN silver wrist watch with black band
Photo Courtesy of: Ian Schon, Schon DSGN

If you could give one piece of advice to a new machinist ready to take the #PlungeIntoMachining, what would it be?

Find a mentor who supports you and challenges you. Find a good tooling company, or good tooling companies, and make good relationships with their tech support so you can get answers. Make good relationships with service technicians who can help you fix your machines. Be a good person. Don’t let yourself become a hot head under the pressure of this industry (since it can be hard at times!), cooler heads prevail, always. Be open to seeing things from other viewpoints (in life and in machining), don’t be afraid to flip a part around and start over from square one.

To learn more about Ian and Schon DSGN, follow them @schon_dsgn and @the_schon on Instagram and check out his website. And, to learn more about how Ian got his start in the manufacturing industry, check out this video.

Successful Slotting With Miniature Cutting Tools

Whether your tool is a 1” diameter powerhouse rougher or a .032” precision end mill, slotting is one of the hardest operations on the tool. During slotting operations, a lot of force and pressure is placed on the entire cutting edge of the tool. This results in slower speeds and feeds and increased tool wear, making it one of the nastier processes even for the best cutting tools.

With miniature tooling (for the purposes of this blog, under 1/8” diameter) the game changes. The way we approach miniature tooling is completely different as it relates to slotting. In these instances, it is vitally important to select the correct tool for these operations. A few of the suggestions may surprise you if you are used to working with larger tooling, but rest assured, these are tried and tested recommendations which will dramatically increase your success rate in miniature slotting applications.

Use as Many Flutes as Possible

When running traditional slotting toolpaths, the biggest concern with the cutting tool is getting the best chip evacuation by using the proper flute count. Traditionally speaking, you want to use the fewest amount of flutes possible. In Aluminum/Non-Ferrous jobs, this is typically no more than 2/3 flutes, and in Steel/Ferrous applications, 4 flutes is recommended. The lower flute count leaves room for the chips to evacuate so you are not re-cutting chips and clogging the flutes on your tool in deep slots.

Achieve Increased Efficiency With Miniature Tooling – Utilize Harvey Tool’s Speeds & Feeds Charts Today

When slotting with miniature tools, the biggest concerns are with tool rigidity, deflection, and core strength. With micro-slotting we are not “slotting”, but rather we are “making a slot”. In traditional slotting, we may drive a ½” tool down 2xD into the part to make a full slot, and the tool can handle it! But this technique simply isn’t possible with a smaller tool.

graphic showing difference between core sizes on 3 flute and 5 flute slotting tools

For example, let’s take a .015” end mill. If we are making a slot that is .015” deep with that tool, we are likely going to take a .001” to .002” axial depth per pass. In this case, chips are no longer your problem since it is not a traditional slotting toolpath. Rigidity and core strength are now key, which means we need to add as many flutes as possible! Even in materials like Aluminum, 4 or 5 flutes will be a much better option at smaller diameters than traditional 2/3 flute tools. By choosing a tool with a higher flute count, some end users have seen their tool life increase upwards of 50 to 100 times over tools with lower flute counts and less rigidity and strength.

Use the Strongest Corner Possible When Slotting

Outside of making sure you have a strong core on your miniature tools while making a slot, you also need to take a hard look at your corner strength. Putting a corner radius on your tooling is a great step and does improve the corner strength of the tool considerably over a square profile tool. However, if we want the strongest tip geometry, using a ball nose end mill should also be considered.

A ball nose end mill will give you the strongest possible tip of the three most common profiles. The end geometry on the ball nose can almost work as a high feed end mill, allowing for faster feed rates on the light axial passes that are required for micro-slotting. The lead angle on the ball nose also allows for axial chip thinning, which will give you better tool life and allow you to decrease your cycle times.

.078" harvey tool ball nose end mill for slotting
A .078″ ball nose end mill was used for this miniature slotting operation

Finding the Right Tool for Miniature Slotting Operations

Precision and accuracy are paramount when it comes to miniature tooling, regardless of whether you are slotting, roughing, or even simply looking to make a hole in a part. With the guidelines above, it is also important to have a variety of tooling options available to cater to your specific slotting needs. Harvey Tool offers 5 flute end mills down to .015” in diameter, which are a great option for a stronger tool with a high flute count for slotting operations.

miniature .010" harvey tool end mill
Harvey Tool offers many miniature end mill options, like the .010″ long reach end mill above.

If you are looking to upgrade your corner strength, Harvey Tool also offers a wide selection of miniature end mills in corner radius and ball nose profiles, with dozens of reach, length of cut, and flute count options. Speeds and feeds information for all of these tools is also available, making your programming of these difficult toolpaths just a little bit easier.

speeds and feeds chart ad

Achieving Slotting Success: Summary

To wrap things up, there are three major items to focus on when it comes to miniature slotting: flute count, corner strength, and the depth of your axial passes.

It is vital to ensure you are using a corner radius or ball nose tool and putting as many flutes as you can on your tool when possible. This keeps the tool rigid and avoids deflection while providing superior core strength.

For your axial passes, take light passes with multiple stepdowns. Working your tool almost as a high feed end mill will make for a successful slotting operation, even at the most minuscule diameters.