Green Manufacturing: Lasting Environment & Shop Benefits

“Green Manufacturing” has become a common phrase used by many in America’s largest industry. It is defined by Goodwin College as “the renewal of production processes and the establishment of environmentally friendly operations within the manufacturing field.” Taking the time to rethink dated processes can save you time, money, and help build your reputation as a state-of-the-art business. The establishment of environmentally friendly machining processes is a huge leap in the right direction of creating an eco-friendly business.

Green Manufacturing is the next logical step forward for the industry.

How to Get Started with Green Manufacturing

The first step you should take on your march toward a more sustainable machine shop, and green manufacturing, is an evaluation of your facilities environmental impact. The most common method for environmental impact assessment of the manufacturing process is Life Cycle Assessment or LCA. ISO 14040 defines LCA as the compilation and evaluation of the inputs, outputs, and the potential environmental impacts of a product system throughout its life cycle.

4 Questions to Ask Yourself:

  1. Goal Definition and Scoping – What am I trying to achieve in this investigation?
  2. Inventory Analysis – What are the quantified inputs (energy, water, materials, etc.) and outputs (air emission, wastewater)?
  3. Impact Assessment – How do these things affect the environment?
  4. Interpretation – What can I change to make my processes more efficient and eco-friendly?

There are databases available to help with the inventory analysis. These databases collect information such as feed rate, cutting speed, tool diameter, cutting time, coolant properties, and then calculate all the material, and energy inputs and outputs.

Understanding the Impact of Cutting Fluids

Cutting fluids are most likely the number one pollutant in your machine shop, and are getting in your way of achieving green manufacturing. According to Modern Manufacturing Processes, North American manufacturers consumed more than 2 billion gallons in 2002, and the metal working fluid market has only grown since then. Cutting fluids have a number of benefits to the machining process, mostly involving cooling of the cutting region, lubrication, and chip evacuation.

Contaminants

Getting the most out of your coolant is a key factor of cost efficiency in any machine shop. Therefore, one of the largest problems you are likely to face, or are currently facing, is the deterioration of cutting fluid performance due to contaminants. The most common types of contaminants include:

  1. Free oils (tramp or sump oil) – Liquid that lubricates the gears and equipment of CNC machine seeping into the cutting fluid
  2. Coarse Particulates – Relatively larger solid waste, chips, and swarf
  3. Fine Particulates – Extremely small pieces of the workpiece or cutting tool that usually consist of heavy metals such as cobalt, cadmium, chromium, aluminum, and lead
  4. Microorganisms – Bacteria and fungi that grow inside the walls and pipes of the CNC machine

Coarse particulates such as chips and swarf are generally easily extracted using an H-Chain, chain and flight, push bar, or a flume system. Fine particulates are more difficult as they require either separation or filtration in the form of setting tanks, foam separators, centrifugal separation, or magnetic separators. Free oil can also be removed through filtration but can also be taken care of quickly and easily with a skimmer.

The right filtration system can both save machine shops money and help the environment.

Microorganisms are the most difficult to remove as they can be a tenth of the size of fine particulates. “Monday morning stink” is a common side effect of anaerobic bacteria excreting hydrogen sulfide during their metabolic processes. These organisms are one of the main reasons coolant has to be drained and changed from a machine every few months. Advancements in technology over the past few decades have made it possible for membrane microfiltration systems to separate biomass, as well as oil from coolant fluids. With these types of systems, operators will no longer have to use problematic biocides as these have troublesome health effects for both the environment and employees. However, it is important to note that most of the microorganisms aren’t growing in the cutting fluid but on the walls/pipes of the machine or buried in the residue of chips at the bottom of the tank.

Some ways of reducing microorganism build-up in your shop include:

  • Keeping machines clean – sludge, swarf, and chips can be a breeding ground for bacteria
  • Reduce organic contamination – spit, sweat, tobacco juice, and organic matter are all a food source for microorganisms
  • Reduce the amount of tramp oil – This can also be a food source

A dirty pile of chips where bacteria will grow and stink up your machine.

Types of Cutting Fluids

A good cutting fluid should have a high flash point, good adhesiveness, high thermal stability, and high oxidative stability. A high flash point is necessary as the fluid should not catch fire at high temperatures (gasoline has a low flash point). Good adhesiveness allows fluid to stick to the surface of the workpiece. This creates a layer between the cutting tool and the workpiece, helping to separate them and thus, reducing friction. Greater amounts of friction leads to higher cutting force, which leads to higher cutting temperatures.

High cutting temperatures are problematic, as this causes the cutting tool to wear faster and can also cause your workpiece to workharden. High thermal stability means that at high temperatures, the fluid should have a low viscosity (an example of a fluid with high viscosity would be honey at room temperature). A lower viscosity in the cutting region allows for a lower amount of friction, and therefore lower amounts of heat and cutting force. A cutting fluids oxidative stability ultimately decides how long that cutting fluid can be used. After a while, oil begin to oxidize, which then causes its viscosity and amount of deposits of sludge to rise.

Excessive amounts of coolants can mean an excessive amount of waste.

For the purpose of this article, cutting fluids will be placed into two broad categories: biodegradable and non-biodegradable.

Non-Biodegradable Coolants

Non-biodegradable coolants are petroleum-based. They have high human and ecological toxicity, which results in occupational health risks. They also have a complicated disposal processes.

Biodegradable Coolants

Biodegradable coolants are plant-based. These are usually manufactured from vegetables such as soy, coconut and canola, or non-edible plants such as neem, karanja, and jatropha. This factor makes them a renewable resource and less toxic to humans, as well as the environment.

In recent years, some modified vegetable-based oils have surpassed petroleum based oils in performance in regards to surface finish, heat suppression and lubrication. One study, published in Science Direct, centered on turning in 304 stainless steel revealed that coconut oil with a boric acid additive was significantly better at combating tool flank wear and surface roughness when compared to two other cutting fluids. This was due to the vegetable-based solutions high thermal stability.

Another study, published in IOP Science, found that a combination of neem and karanja oil was superior to SAE 20W40 (petroleum based oil) in regards to lubrication when drilling mild steel. The results showed that the vegetable-based oil solution reduced the cutting force of the operation due to its higher viscosity and adhesiveness. This ultimately led to a better surface finish on the part.

Summary of Cost Efficient Coolant Changes You Can Make

  • Reduce microorganism build up in your machines by keeping the machines clean and reducing amount of outside contamination
  • Install a membrane microfiltration system
  • Switch to a more efficient and biodegradable cutting fluid

The Positive Green Machining Impact of Dry Machining

Dry machining should be utilized whenever the opportunity presents itself, as the costs and environmental issues associated with cutting fluid obtainment, management, and disposal are eliminated. Another benefit to dry machining is the absence of thermal shock. When the cutter exits the cut but coolant is still blasting, the large temperature fluctuation (thermal shock) will cause the cutting edge to break down quicker than if it were to run hot full time. Dry machining is most prevalent in machining operations with interrupted cuts or when cutting hardened steels. It is especially popular in milling operations with high speeds and feeds. Cutting with high running parameters allows for most of the heat to be dispersed into the chips rather than into the workpiece. This is also the case when machining hardened steels.

Ideal Tooling for Dry Machining

The ideal cutting tool should be more heat resistant, and less heat generative. Carbide is a good substrate as it is extremely hard and strong. Coated tools are the best option for dry machining as they have improved thermal insulation as well as improved self-lubrication.

The Positive Affect of Minimum Quantity Lubrication (MQL)

  • Significantly reduced fluid consumption
  • Safer cutting fluids and lubricants
  • Reduced health hazards for employees
  • Cleaner shop environment
  • Reduced maintenance

Because such a small quantity of fluid is used in MQL, this make it a perfect application to use slightly pricier vegetable-based oils. MQL has been found to be most effective in sawing and drilling operations.

The Benefits of Green Manufacturing

Taking a second look at your current machining operations through and environmentalist lens can save you time, money, and create a less hazardous work place for your employees. Using the techniques above, one can approximate shop efficiency and make appropriate changes for the benefit of current and future generations.

The Geometries and Purposes of a Slitting Saw

When a machinist needs to cut material significantly deeper than wide, a Slitting Saw is an ideal choice to get the job done. A Slitting Saw is unique due to its composition and rigidity, which allows it to hold up in a variety of both straightforward and tricky to machine materials.

What is a Slitting Saw?

A Slitting Saw is a flat (with or without a dish), circular-shaped saw that has a hole in the middle and teeth on the outer diameter. Used in conjunction with an arbor, a Slitting Saw is intended for machining purposes that require a large amount of material to be removed within a small diameter, such as slotting or cutoff applications.

Other names for Slitting Saws include (but are not limited to) Slitting Cutters, Slotting Cutters, Jewelers Saws, and Slitting Knives. Both Jewelers Saws and Slitting Knives are particular types of Slitting Saws. Jewelers Saws have a high tooth count enabling them to cut tiny, precise features, and Slitting Knives are Slitting Saws with no teeth at all. On Jewelers Saws, the tooth counts are generally much higher than other types of saws in order to make the cuts as accurate as possible.

Key Terminology

Why Use a Slitting Saw?

These saws are designed for cutting into both ferrous and non-ferrous materials, and by utilizing their unique shape and geometries, they can cut thin slot type features on parts more efficiently than any other machining tool.

Common Applications:

  1. Separating Two Pieces of Material
    1. If an application calls for cutting a piece of material, such as a rod, in half, then a slitting saw will work well to cut the pieces apart while increasing efficiency.
  2. Undercutting Applications
    1. Saws can perform undercutting applications if mounted correctly, which can eliminate the need to remount the workpiece completely.
  3. Slotting into Material
    1. Capable of creating thin slots with a significant depth of cut, Slitting Saws can be just the right tool for the job!

When Not to Use a Slitting Saw

While it may look similar to a stainless steel circular saw blade from a hardware store, a Slitting Saw should never be used with construction tools such as a table or circular saw.  Brittle saw blades such as slitting saws will shatter when used on manual machines, and can cause injury when not used on the proper set up.

In Conclusion

Slitting Saws can be beneficial to a wide variety of machining processes, and it is vital to understand their geometries and purpose before attempting to utilize them in the shop. They are a great tool to have in the shop and can assist with getting jobs done as quickly and efficiently as possible.

Machining Precious Metals

Precious metals can be particularly difficult to machine due to their wide range of material properties and high cost if a part has to be scrapped. The following article will introduce these elements and their alloys as well as provide a guide on how to machine them effectively and efficiently.

About the Elements

Sometimes called “noble” metals, precious metals consist of eight elements that lie in the middle of the periodic table (seen below in Figure 1). The eight metals are:

  1. Ruthenium (Ru)
  2. Rhodium (Rh)
  3. Palladium (Pd)
  4. Silver (Ag)
  5. Osmium (Os)
  6. Iridium (Ir)
  7. Platinum (Pt)
  8. Gold (Au)

These elements are some of the rarest materials on earth, and can therefore be enormously expensive. Gold and silver can be found in pure nugget form, making them more easily available. However, the other six elements are typically found mixed in the raw ore of the four metals they sit below on the periodic table: Iron (Fe), Cobalt (Co), Nickel (Ni), and Copper (Cu). These elements are a subset of precious metals and are generally called Platinum Group Metals (PGM). Because they are found together in raw ore, this makes mining and extraction difficult, dramatically increasing their cost. Because of their high price tag, machining these materials right the first time is incredibly important to a shop’s efficiency.

machining metals

Figure 1: Periodic table with the 8 precious metals boxed in blue. Image source: clearscience.tumblr.com

Basic Properties and Compositions of Precious Metals

Precious metals have notable material properties as they are characteristically soft, ductile, and oxidation resistant. They are called “noble” metals because of their resistance to most types of chemical and environmental attack. Table 1 lists a few telling material properties of precious metals in their elemental form. For comparison purposes, they are side-by-side with 6061 Al and 4140 Steel. Generally, only gold and silver are used in their purest form as the platinum group metals are alloys that consist mainly of platinum (with a smaller composition of Ru, Rh, Pa, Os, Ir). Precious metals are notable for being extremely dense and having a high melting point, which make them suitable for a variety of applications.

Table 1: Cold-worked Material Properties of Precious Metals, 4140 Steel and 6061 Aluminum 

precious metals

Common Machining Applications of Precious Metals

Silver and gold have particularly favorable thermal conductivity and electrical resistivity. These values are listed in Table 2, along with CC1000 (annealed copper) and annealed 6061 aluminum, for comparison purposes. Copper is generally used in electrical wiring because of its relatively low electrical resistivity, even though silver would make a better substitute. The obvious reason this isn’t the general convention is the cost of silver vs. copper. That being said, copper is generally plated with gold at electrical contact areas because it tends to oxide after extended use, which lowers its resistivity. As stated before, gold and the other precious metals are known to be resistant to oxidation. This corrosion resistance is the main reason that they are used in cathodic protection systems of the electronics industry.

Table 2: Thermal Conductivity and Electrical Resistivity of Ag, Au, Cu, and Al 

machining metals

Platinum and its respective alloys offer the most amount of applications as it can achieve a number of different mechanical properties while still maintaining the benefits of a precious metal (high melting point, ductility, and oxidation resistance). Table 3 lists platinum and a number of other PGMs each with their own mechanical properties. The variance of these properties depends on the alloying element(s) being added to the platinum, the percentage of alloying metal, and whether or not the material has been cold-worked or annealed. Alloying can significantly increase the tensile strength and hardness of a material while decreasing its ductility at the same time. The ratio of this tensile strength/hardness increase to ductility decrease depends on the metal added as well as how much is added, as seen in Table 3. Generally this depends on the particle size of the element added as well as its natural crystalline structure. Ruthenium and Osmium have a specific crystal structure that has a significant hardening effect when added to platinum. Pt-Os alloys in particular are extremely hard and practically unworkable, which doesn’t yield many real-world applications. However, the addition of the other 4 PGMs to platinum allow for a range of mechanical properties with various usages.

Table 3: PGM material properties (Note: the hardness and tensile strength are cold worked values) 

machining metals

Platinum and its alloys are biocompatible, giving them the ability to be placed in the human body for long periods of time without causing adverse reactions or poisoning. Therefore, medical devices including heart muscle screw fixations, stents, and marker bands for angioplasty devices are made from platinum and its alloys. Gold and palladium are also commonly used in dental applications.

Pt-Ir alloys are noticeably harder and stronger than any of the other alloys and make excellent heads for spark plugs in the automobile industry. Rhodium is sometimes added to Pt-Ir alloys to make the material less springy (as they are used as medical spring wire) while also increasing its workability. Pt and Pt-Rh wire pairs are extremely effective at measuring temperatures and are therefore used in thermocouples.

Machining Precious Metals

The two parameters that have the most effect when machining are hardness and percent elongation. Hardness is well-known by machinists and engineers across the manufacturing industry as it indicates a material’s resistance to deformation or cutting. Percent elongation is a measurement used to quantify material ductility. It indicates to a designer the degree to which a structure will deform plastically (permanently) before fracture. For example, a ductile plastic such as ultrahigh molecular weight polyethylene (UHMWPE) has a percent elongation of 350-525%, while a more brittle material such as oil-quenched and tempered cast iron (grade 120-90-02) has a percent elongation of about 2%. Therefore, the greater the percent elongation, the greater the material’s “gumminess.” Gummy materials are prone to built-up edge and have a tendency to produce long stringy chips.

Tools for Precious Metals

Material ductility makes a sharp cutting tool essential for cutting precious metals. Variable Helix for Aluminum Alloy tools can be used for the softer materials such as pure gold, silver, and platinum.

machining metals

Figure 2: Variable Helix Square End Mill for Aluminum Alloys

Higher hardness materials still require a sharp cutting edge. Therefore, one’s best option is to invest in a PCD Diamond tool. The PCD wafer has the ability to cut extremely hard materials while maintaining a sharp cutting edge for a relatively long period of time, compared to standard HSS and carbide cutting edges.

machining metals

Figure 3: PCD Diamond Square End Mill

Speeds and Feeds charts:

machining metals

Figure 4: Speeds and Feeds for precious metals when using a Square Non-ferrous, 3x LOC

 

machining metals

Figure 5: Speeds and Feeds for precious metals when using a 2-Flute Square PCD end mill

 

An Introduction to Reamers & CNC Reaming

Most machinists are familiar with CNC drilling, but did you know that the common practice for holemaking is to always use a reamer? When done correctly, reaming can be a fast and highly accurate operation that results in precision holes.

Critical Reamer Geometries

reamers

By examining a Harvey Tool Miniature Reamer and its critical dimensions, we can better understand the functionality of this useful tool. In the above image, D1 references the reamer diameter, the specific size intended for your hole; and D2 points to the shank diameter. At Harvey Tool, reamer shanks are oversized to help maintain tool strength, stiffness, and accuracy. Shanks also have an h6 tolerance, which is crucial for high precision tool holders, such as heat shrink collets. Other critical dimensions of a reamer include its overall length (L1), margin length (L2), overall reach (L3), and chamfer length (L4).

The Functions of Miniature Reamers

Reamers Provide Precision – As mentioned earlier, reamers are great for machining precision hole diameters. To use a reamer properly, you must first have a pre-drilled hole that’s between 90% and 94% of the final hole diameter. For example, if you need a finished a hole of .220″, your predrilled hole should be somewhere between .1980″ and .2068″. This allows the tool to take enough material off to leave a great finish, but does not overwork it, potentially causing damage. The tolerance for uncoated reamers is +.0000″/-.0002″, while the tolerance for AlTiN coating is +.0002″/-.0000″. These tolerances provide you the peace of mind of knowing that your hole will meet exact specifications.

Achieve a Quality CNC Finish – When a high surface finish is required of a hole, reamers should always be used to reach the desired tolerance. Both the pre-drilled hole and the tool’s margin help to keep the reamer centered while cutting, leading to a better finish.

Minimize Machining Production Runs – For machine shops, consistency is a priority. This is especially true in production runs. The last thing a machinist wants to see is an oversized hole on a part they have already preformed many operations on. Remember, reamers have the benefit of offering consistent hole size, preventing an out of tolerance finish. These consistent holes lead to valuable time savings and reduced scrap costs.

CNC Machining Exotic Alloys: When machining Inconel, titanium, and other high-cost materials, reaming your hole is important to ensure that the desired finish specification is met. With reamers, a machinists can better predict tool life, leading to a better finished product and less scrap ratios. It is important to note that Harvey Tool reamers are offered AlTiN coated and fully stocked in every .0005” increment from .0080” to .0640”.

When To and Not To Use Drop Hole Allowance

Dovetail Cutters are cutting tools that create a trapezoidal-type shape, or a dovetail groove, in a part. Due to the form of these tools, special considerations need to be made in order to achieve long tool life and superior results. This is particularly true when machining O-ring grooves, as this operation requires the tool to drop into the part to begin cutting. Using an appropriate tool entry method, specifically understanding when drop hole allowance is (and is not) needed, is important to keep common dovetail mishaps from occurring.

What is a Drop-Hole?

When designing parts featuring O-ring grooves, the consideration of drop-hole allowance is a pivotal first step. A drop-hole is an off-center hole milled during the roughing/slotting operation. This feature allows for a significantly larger, more rigid tool to be used. This is because the cutter no longer has to fit into the slot, but into a hole with a diameter larger than its cutter diameter.

drop hole allowance

Why consider adding a Drop-Hole?

When compared to tools without drop-hole allowance, tools with drop-hole allowance have a much larger neck diameter-to-cutter diameter ratio. This makes the drop-hole tools far stronger, permitting the tool to take heavy radial depths of cut and fewer step-overs. Using a drop-hole will allow the use of the stronger tool, which will increase production rate and improve tool life.

Machining Operation with Drop-Hole Allowance

drop hole allowance

A maximum of 4 radial passes per side are needed.

When Not to Drop Hole

Drop-holes are sometimes not permitted in a design due to the added stress concentration point it leaves. Common examples for where a drop-hole would not be allowed include:

  • In high pressure applications
  • In seals requiring a high reliability
  • Where dangerous or hazardous fluids are being used

The issue with drop-hole allowance is that the additional clearance used for tool entry can create a weak spot in the seal, which can then become compromised under certain conditions. Ultimately, drop-hole allowance requires approval from the customer to ensure the application allows for it.

Machining Operation Without Drop-Hole Allowance

drop hole allowance

A maximum of 20 radial passes per side are needed.

Drop-Hole Placement

When adding a drop-hole to your part, it is important to ensure that the feature is placed correctly to maximize seal integrity. Per the below figure, the drop-hole should be placed off center of the groove, ensuring that only one side of the groove is affected.

drop hole allowance

It is also necessary to ensure that drop-hole features are put on the correct side of the groove. Since O-rings are used as a seal between pressures, it is important to have the drop-hole bordering the high pressure zone. As pressure moves from high to low, the O-ring will be forced into the fully supported side, allowing for a proper seal (See image below).

drop hole allowance

What To Know About Helical Solution’s Zplus Coating

Non-ferrous and non-metallic materials are not usually considered difficult to machine, and therefore, machinists often overlook the use of tool coatings. But while these materials may not present the same machining difficulties as hardened steels and other ferrous materials, a coating can still vastly improve performance in non-ferrous applications. For instance, materials such as aluminum and graphite can cause machinists headaches because of the difficulty they often create from abrasion. To alleviate these issues in non-ferrous machining applications, a popular coating choice is Helical Solution’s Zplus coating.

zplus coating

What is Helical Solutions’ Zplus Coating?

Helical’s Zplus is a Zirconium Nitride-based coating, applied by a Physical Vapor Deposition (PVD) process. This method of coating takes place in a vacuum and forms layers only microns thick onto the properly prepared tool. Zirconium Nitride does not chemically react to a variety of non-ferrous metals, increasing the lubricity of the tool and aiding in chip evacuation.

zplus coating

When Should a Machinist Use Helical Solution’s Zplus?

Working with Abrasive Materials

While Zplus was created initially for working in aluminum, its hardness level and maximum working temperature of 1,110°F enables it to work well in abrasive forms of other non-ferrous materials, as well. This coating decreases the coefficient of friction between the tool and the part, allowing it to move easier through more abrasive materials. This abrasion resistance decreases the rate of tool wear, prolonging tool life.

Concerns with Efficient Chip Evacuation

One of the primary functions of this coating is to increase the smoothness of the flutes of the tool, which allows for more efficient chip removal. By decreasing the amount of friction between the tool and the material, chips will not stick to the tool, helping to prevent chip packing. The increased lubricity and smoothness provided by the coating allows for a higher level of performance from the cutting tool. Zplus is also recommended for use in softer, gummy alloys, as the smooth surface encourages maximum lubricity within the material – this decreases the likelihood of those gummier chips sticking to the tool while machining.

Large Production Runs

Uncoated tools can work well in many forms of non-ferrous applications. However, to get a genuinely cost-effective tool for your job, the proper coating is highly recommended. Large production runs are known for putting a lot of wear and tear on tools due to their increased use, and by utilizing an appropriate coating, there can be a significant improvement in the tools working life.

When is Zplus Coating Not Beneficial to My Application?

Finishing Applications

When your parts finish is vital to its final application, a machinist may want to consider going with an uncoated tool. As with any coating, ZrN will leave a very minor rounded edge on the tip of the cutting edge. The best finish often requires an extremely sharp tool, and an uncoated tool will have a sharper cutting edge than its coated version.

 

Chipbreakers vs. Knuckle Rougher End Mills

Knuckle Roughers and Chipbreakers are common profiles found on roughing end mills that, while fairly similar in appearance, actually serve different functions. Chipbreakers refer to the notches along the cutting edge of a tool that work to break up chips to prevent common evacuation mishaps. Knuckle Roughers refer to the serrated cutting edge of a tool, which works to enhance cutting action for an overall smoother operation.

Determining the appropriate style of tool is a very important first step to a successful roughing application.

Understanding the Two Styles

Chipbreaker End Mills

To aid chip evacuation, Chipbreaker End Mills feature a notched profile along the cutting edge that break down long chips into smaller, more manageable pieces. These tools are often utilized in aluminum jobs, as long, stringy chips are common with that material.

Each notch is offset flute-to-flute to enhance the surface finish on the part. This works by ensuring that as each flute rotates and impacts a part, following flutes work to clean up any marks or extra material that was left behind by the first pass. This leaves a semi-finished surface on your part.

In addition to improving chip control and reducing cutting resistance, these tools also help in decreasing heat load within the chips. This delays tool wear along the cutting edge and improves cutting performance. Not only are these tools great for hogging out a great deal of material, but they can be utilized in a wide array of jobs – from aluminum to steels. Further, a machinist can take full advantage of the unique benefits this tool possesses by utilizing High Efficiency Milling toolpaths, meant to promote efficiency and boost tool life.

Knuckle Roughers

Knuckle Rougher End Mills have a serrated cutting edge that generates significantly smaller chips than a standard end mill cutting edge. This allows for smoother machining and a more efficient metal removal process, similar to Chipbreaker End Mills. However, the serrations chop the chips down to much finer sizes, which allows more chips into the flutes during the evacuation process without any packing occurring.

Designed for steels, Knuckle Rougher End Mills are built to withstand harder materials and feature a large core. Because of this, these tools are great for roughing out a lot of material. However, due to the profile on the cutting edge, tracks along the wall can sometimes be left on a part. If finish is a concern, be sure to come in with a finishing tool after the roughing operation. Knuckle Roughers have proven the ability to run at higher chip loads, compared to similar end mills, which makes this a highly desired style for roughing. Further, this style of rougher causes a lot of heat and friction within the chips, so it’s important to run flood coolant when running this tool.

Key Differences Between Knuckle Roughers & Chipbreakers

While the two geometries offer similar benefits, it’s important to understand the distinct differences between them. Chipbreakers feature offset notches, which help to leave an acceptable finish on the walls of a part. Simply, the material left on an initial flute pass is removed by subsequent passes. A Knuckle Rougher does not feature this offset geometry, which can leave track marks on your part. Where part finish is of upmost importance, utilize a Knuckle Rougher to first hog out a great deal of steel, and work a final pass with a Finishing End Mill.

A unique benefit of Knuckle Roughers is the grind they possess – a cylindrical grind, compared to a relieved grind of a Chipbreaker End Mill. Because of this, Knuckle Roughers are easier to resharpen. Therefore, instead of buying a new tool, resharpening this profile is often a cheaper alternative.

How Material Specific Tooling Pays Off

A machinist is faced with many questions while selecting the proper tool for their job. One key decision that must be made is whether a material specific tool is appropriate and necessary for the application that’s going to be performed – whether the benefits of using this type of tool outweigh the higher price tag than that of a tool designed for use in a variety of materials. There are four main categories to consider when deciding whether a material specific tool is your best bet: internal tool geometry, coatings, material removal rates (MRR), and cost.

When to Utilize Material Specific Tooling

Are you a machinist in a shop that deals primarily with one type of material? Or, do you generally change materials frequently throughout the day? Further, how many parts do you make at a time? These are questions you must ask yourself prior to making a tooling decision.

Material Specific Tooling is best utilized where several parts are being machined of the same material. For instance, if your shop is machining 1,000 plastic parts, it would be in your best interest to opt for a tool designed for this material as your tooling would not only last longer but perform better. If machining flexibility is paramount for your shop, if you’re only machining a few parts, or if part finish is not of high importance, a regular end mill may suffice.

Pros and Cons of Material Specific Tooling

There are pros and cons to purchasing a Material Specific Tool.

Pros:

  • Tool geometry designed for the material you’re working in to achieve the best results.
  • Coating optimized for the material you’re cutting.
  • More aggressive speeds and feeds, and boosted MRR as a result.
  • Increased tool life.

Cons:

  • Higher upfront cost, though long term savings are possible if used in proper situations.
  • Less opportunity for flexibility. While most end mills may be suitable for use in many jobs and many machines, Material Specific End Mills are engineered for use in specific materials

Special Benefits of Material Specific Tooling

A Unique Internal Tool Geometry

Many manufacturers supply tooling designed for use in specific material buckets. For instance, Harvey Tool has distinct catalog sections for material specific tooling for Hardened Steels, Exotic Alloys, Medium Alloy Steels, Free Machining Steels, Aluminum Alloys, Plastics, Diamond Tooling for Non-Ferrous Materials, and Composites. The special geometry of tools found in these sections is optimized to allow the tool to perform optimally in its select material group.

For instance, a machinist may be faced with a dilemma while preparing to machine a plastic part. While an end mill found in Harvey Tool’s Miniature End Mill section could certainly machine this material, Harvey Tool’s end mill offering designed to machine plastics feature a high rake, high relief design. This is ideal for plastics because you want to effectively cut and form chips while the strength of the tool is less of a concern. The high rake and high relief creates a sharp cutting edge that would quickly break down in metals. However, in plastics, this effectively shears the material and transfers the heat into the chip to produce a great finish in your part.

material specific tooling

Harvey Performance Company, LLC.

Specific Coatings & Substrates for Optimal Performance

One key benefit of opting for a material specific tool is the ability to utilize the best coating option available for that material. Tool coatings serve many functions, including improved lubricity, increased tool life, and a higher-quality part finish. In addition, coated tools can typically be run around 10% faster than uncoated tools.

While many manufacturers will specially coat a standard end mill at your request, this takes added time and cost. In its Material Specific catalog sections, Harvey Tool offers coated tools stocked and ready to ship. For instance, their Hardened Steels and Exotic Alloys categories utilize AlTiN Nano coating. This is a unique nanocomposite coating that has a max working temperature of 2,100° F and shows improved performance in materials such as Hardened Steels, Titantium Alloys, and Inconel, among others.

Increased Material Removal Rates

Because Material Specific Tooling features optimal tool geometry for a job, running parameters are generally able to be more aggressive. Any machinist knows that Material Removal Rates (MRR), is the metric that’s most closely related to shop efficiency, as the more material removed from a part in a given period of time, the faster parts are made and the higher the shop output.

The following example compares running parameters of end mills from Harvey Tool’s Miniature End Mill and Material Specific End Mill Sections. You can notice that while key geometries between the two tools are identical, and are in use in the same material with the same operation, the chip load (+25%), linear feed rate (+33%), and depth of cut (+43%) are boosted. This allows for more material to be removed in a shorter period of time.

Miniature End Mill

Part Number: 836408

Description: 3 Flute 1/8 inch diameter 3x LOC Square Stub & Standard

Material: 6061 Aluminum

Application: Slotting

Speed: 10,000 RPM

Chip Load: .00124 IPT

Linear Feed: 37.2 IPM

DOC: .04375

material specific tooling

Harvey Performance Company, LLC.

 

Material Specific End Mill

Part Number: 942308

Description: 3 Flute 1/8 inch diameter 3x LOC Square Variable Helix for Aluminum Alloys

Material: 6061 Aluminum

Application: Slotting

Speed: 10,000 RPM

Chip Load: .00165 IPT

Linear Feed: 49.5 IPM

DOC: .0625

material specific tooling

Harvey Performance Company, LLC.

Extensive Cost Savings

The following chart displays a cost analysis breakdown between a tool found in the Miniature End Mill section, item 993893-C3; and a tool found in the Material Specific End Mill section, item 933293-C6. When compared for the machining of 1,000 parts, the overall savings is nearly $2,500.

material specific tooling

Material Specific Tooling Summarized

In conclusion, Material Specific End Mills have many benefits, but are best utilized in certain situations. While the initial cost of these tools are higher, they can work to save your shop time and money in the long run by lasting longer and producing more parts over a given period of time.

Confidently Select Your Next Thread Mill

Do you know the key differences between a Single Form Thread Mill and a Multi-Form Thread Mill? Do you know which tooling option is best for your job? This blog post examines how several factors, including the tool’s form and max depth of thread, are important to ultimately making the appropriate Harvey Tool thread mill decision.

Thread Mill Product Offering

Single Form Thread Mill

The single form thread mill is the most versatile threading solution Harvey Tool offers. These tools are ground to a sharp point and are capable of milling 60° thread styles, such as UN, metric, and NPT threads. With over 14 UN and 10 Metric sized tools, Harvey Tool’s single form selections allow machinists the opportunity to machine many different types of threads.

Thread Mill

Harvey Performance Company, LLC.

Single Form Thread Mills for Hardened Steels

Similar to the standard single form thread mills, Harvey Tool’s thread mills for hardened steels offer machinists a quality option when dealing with hardened steels from 46-68 Rc. The following unique geometries helps this tool machine tough alloys:

  1. Ground Flat – Instead of a sharp point these tools have a ground flat to help ensure long tool life.
  2. Eccentric Relief – Gives the cutting edges extra strength for the high feeds at relatively low RPMs required for harder materials.
  3. AlTiN Nano Coating – Allows for superior heat resistance.
thread mill

Harvey Performance Company, LLC.

A key difference between the standard Single Form Thread Mill and the Single Form Thread Mills for Hardened Steels is that the thread mills for hardened steels are actually only capable of milling 83% of the actual thread depth. At first, this may seem detrimental to your operation. However, according to the Machinery’s Handbook 29th Edition, “Tests have shown that any increase in the percentage of full thread over 60% does not significantly increase the strength of the thread. Often, a 55% to 60% thread is satisfactory, although 75% threads are commonly used to provide an extra margin of safety.” With the ability to preserve tool life and effectively perform thread components, Harvey Tool’s single form thread mills for hardened steels are a natural choice when tackling a hardened material.

Tri-Form Thread Mills

Tri-Form thread mills are designed for difficult-to-machine materials. The tri-form design reduces tool pressure and deflection, which results in more accurate threading. Its left-hand cut, left-hand spiral design allows it to climb mill from the top of the thread to the bottom.

thread mill

Harvey Performance Company, LLC.

Multi-Form Thread Mills

Our multi-form thread mills are offered in styles such as UN, NPT, and Metric. Multi-Form Thread Mills are optimized to produce a full thread in single helical interpolation. Additionally, they allow a machinist to quickly turn around production-style jobs.

thread mill

Harvey Performance Company, LLC.

Coolant-Through Multi Form Thread Mills

Coolant-Through Multi Form Thread Mills are the perfect tool for when a job calls for thread milling in a blind hole. The coolant through ability of the tool produces superior chip evacuation. These tools also improve coolant flow to the workpiece – delivering it directly from the tip of the tool – for decreased friction and high cutting speeds.

thread mill

Harvey Performance Company, LLC.

Long Flute Thread Mills

These tools are great when a job calls for a deep thread, due to their long flute. Long Flute Thread Mills also have a large cutter diameter and core, which provides the tool with improved tool strength and stability.

thread mill

Harvey Performance Company, LLC.

N.P.T. Multi-Form Thread Mills

While it may seem obvious, N.P.T. Multi-Form Thread Mills are perfect for milling NPT threads. NPT threads are great for when a part requires a full seal, different from traditional threads that hold pieces together without the water-tight seal.

thread mill

Harvey Performance Company, LLC.

How to Extend the Life of Your End Mill

Breaking and damaging an end mill is oftentimes an avoidable mistake that can be extremely costly for a machine shop. To save time, money, and your end mill it is important to learn some simple tips and tricks to extend your tool’s life.

Properly Prepare Before the Tool Selection Process

The first step of any machining job is selecting the correct end mill for your material and application. However, this doesn’t mean that there should not be an adequate amount of legwork done beforehand to ensure the right decision on a tool is being made. Harvey Tool and Helical Solutions have thousands of different tools for different operations – a vast selection which, if unprepared – can easily result in selecting a tool that’s not the best for your job. To start your preparation, answer the 5 Questions to Ask Before Selecting an End Mill to help you quickly narrow down your selection and better understand the perfect tool you require.

Understand Your Tooling Requirements

It’s important to understand not only what your tool needs, but also general best practices to avoid common machining mishaps. For instance, it is important to use a tool with a length of cut only as long as needed, as the longer a tools length of cut is, the greater the chance of deflection or tool bending, which can decrease its effective life.

tool life

Another factor to consider is the coating composition on a tool. Harvey Tool and Helical Solutions offer many varieties of coatings for different materials. Some coatings increase lubricity, slowing tool wear, while others increase the hardness and abrasion resistance of the tool. Not all coatings increase your tool’s life in every material, however. Be wary of coatings that don’t perform well in your part’s material – such as the use of AlTiN coating in Aluminum (Both coating and material are aluminum-based and have a high affinity for each other, which can cause built-up edge and result in chip evacuation problems).

Consider Variable Helix & Pitch Geometry

A feature on many of our high performance end mills is variable helix or variable pitch geometry, which have differently-spaced flutes. As the tool cuts, there are different time intervals between the cutting edges contacting the workpiece, rather than simultaneously on each rotation. The varying time intervals minimizes chatter by reducing harmonics, increasing tool life and producing better results.

Ensure an Effective Tool Holding Strategy

Another factor in prolonging tool life is proper tool holding. A poor tool holding strategy can cause runout, pullout, and scrapped parts. Generally, the most secure connection has more points of contact between the tool holder and tool shank. Hydraulic and Shrink Fit Tool Holders provide increased performance over other tightening methods.

tool life

Helical also offers shank modifications to all stocked standards and special quotes, such as the ToughGRIP Shank, which provides added friction between the holder and the shank of the tool for a more secure grip; and the Haimer Safe-Lock™, which has grooves on the shank of the tool to help lock it into place in a tool holder.

tool life

Trust Your Running Parameters, and their Source

After selecting the correct end mill for your job, the next step is to run the tool at the proper speeds and feeds.

Run at the Correct Speed

Understanding the ideal speed to run your machine is key to prolonging tool life. If you run your tool too fast, it can cause suboptimal chip size, ineffective chip evacuation, or even total tool failure. Adversely, running your tool too slowly can result in deflection, bad finish, or decreased metal removal rates.

Push at the Best Feed Rate

Another critical parameter of speeds and feeds is finding the best possible feed rate for your job, for sake of both tool life and achieving maximum shop efficiency. Pushing your tool too aggressively can result in breakage, but being too conservative can lead to recutting chips and excess heat generation, accelerating tool wear.

Use Parameters from Your Tooling Manufacturer

A manufacturer’s speeds and feeds calculations take into account every tool dimension, even those not called out in a catalog and readily available to machinists. Because of this, it’s best to rely on running parameters from tooling manufacturers. Harvey Tool offers speeds and feeds charts for every one of its more than 21,000 tools featured in its catalog, helping machinists to confidently run their tool the first time.

Harvey Performance Company offers the Machining Advisor Pro application, a free, cutting-edge resource that generates custom running parameters for optimized machining with all of Helical’s products.

tool life

Opt for the Right Milling Strategy: Climb vs Conventional

There are two ways to cut material when milling: Climb Milling and Conventional Milling. In conventional milling, the cutter rotates against the feed. In this method, chips will start at theoretical zero and increase in size. Conventional milling is usually recommended for tools with higher toughness, or for breaking through case hardened materials.

In Climb Milling, the cutter rotates with the feed. Here, the chips start at maximum width and decrease, causing the heat generated to transfer into the chip instead of being left in the tool or work piece. Climb milling also produces a cleaner shear plane, causing less rubbing, decreasing heat, and improving tool life. When climb milling, chips will be removed behind the cutter, reducing your chances of recutting.

Utilize High Efficiency Milling

High Efficiency Milling (HEM), is a roughing technique that uses the theory of chip thinning by applying a smaller radial depth of cut (RDOC) and a larger axial depth of cut (ADOC). The parameters for HEM are similar to that of finishing, but with increased speeds and feeds, allowing for higher material removal rates (MRR). HEM utilizes the full length of cut instead of just a portion of the cutter, allowing heat to be distributed across the cutting edge, maximizing tool life and productivity. This reduces the possibility of accelerated tool wear and breakage.

Decide On Coolant Usage & Delivery

Coolant can be an extremely effective way to protect your tool from premature wear and possible tool breakage. There are many different types of coolant and methods of delivery to your tool. Coolant can come in the form of compressed air, water-based, straight oil-based, soluble oil-based, synthetic or semi-synthetic. It can be delivered as mist, flood, high pressure or minimum quantity lubricant.

Appropriate coolant type and delivery vary depending on your application and tool. For example, using a high pressure coolant with miniature tooling can lead to tool breakage due to the fragile nature of extremely small tools. In applications of materials that are soft and gummy, flood coolant washes away the long stringy chips to help avoid recutting and built-up edge, preventing extra tool wear.

Extend Your Tool’s Life

The ability to maximize tool life saves you time, money and headaches. To get the best possible outcome from your tool, you first need to be sure you’re using the best tool for your job. Once you find your tool, ensure that your speeds and feeds are accurate and are from your tooling manufacturer. Nobody knows the tools better than they do. Finally, think about how to run your tool: the rotation of your cutter, whether utilizing an HEM approach is best, and how to introduce coolant to your job.