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.

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.

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

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.

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. If you need even smaller tooling, there are 4 flute options available down to .005” in diameter.

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.

Conclusion

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.

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.

How to Advance Your Machining Career: 8 Tips from Machining Pros

Since we began shining a light on Harvey Performance Company brand customers via “In the Loupe’s,” Featured Customer posts, more than 20 machinists have been asked to share insight relevant to how they’ve achieved success. Each Featured Customer post includes interesting and useful information on a variety of machining-related subjects, including prototyping ideas, expanding a business, getting into machining, advantages and disadvantages of utilizing different milling machine types, and more. This post compiles 8 useful tips from our Featured Customers on ways to advance your machining career.

Tip 1: Be Persistent – Getting Your Foot in the Door is Half the Battle

With machining technology advancing at the amazing rate that it is, there is no better time to become a machinist. It is a trade that is constantly improving, and offers so many opportunities for young people. Eddie Casanueva of Nueva Precision first got into machining when he was in college, taking a job at an on-campus research center for manufacturing systems to support himself.

“The research center had all the workings of a machine shop,” Eddie said. “There were CNC mills, lathes, injection molding machines, and more. It just looked awesome. I managed to get hired for a job at minimum wage sweeping the shop floor and helping out where I could.

As a curious student, I would ask a million questions… John – an expert machinist – took me under his wing and taught me lots of stuff about machining. I started buying tools and building out my toolbox with him for a while, absorbing everything that I could.”

One of the best things about becoming a machinist is that there is a fairly low entry barrier. Many machinists start working right out of high school, with 12-18 months of on-the-job training or a one to two year apprenticeship. Nearly 70% of the machinist workforce is over the age of 45. The Bureau of Labor Statistics is predicting a 10% increase in the machinist workforce with opportunities for 29,000 additional skilled machinists by 2024, so it is certainly a great time to get your foot in the door.

Tip 2: Keep an Open Mind – If You Can Think of It, You Can Machine It

Being open-minded is crucial to becoming the best machinist you can be. By keeping an open mind, Oklahoma City-based company Okluma’s owner Jeff Sapp has quickly earned a reputation for his product as one of the best built and most reliable flashlights on the market today. Jeff’s idea for Okluma came to him while riding his motorcycle across the country.

“I had purchased what I thought was a nice flashlight for $50 to carry with me on the trip. However, two days in to the trip the flashlight broke. Of course, it was dark and I was in the middle of nowhere trying to work on my bike. I’m happy to pay for good tools, but that wasn’t what happened. Not only was there no warranty for replacement, there was no way to fix it. It was just made to be thrown away. That whole attitude makes me angry. When I got home, I decided I was going to put my new skills to work and design and build my own flashlight, with the goal of never running into an issue like I had on my trip ever again. I started by making one for myself, then four, then twenty. That was four years ago. Now I have my own business with one employee and two dogs, and we stay very busy.”

An awesome side benefit to working as a machinist is that you have all the resources to create anything you can dream of, like Jeff did with Okluma.

Image courtesy of Okluma.

Tip 3: Be Patient – Take Time to Ensure Your Job is Setup Correctly before Beginning

The setup process is a huge part of machining, but is often overlooked. Alex Madsen, co- owner of M5 Micro in Minnesota, has been working in manufacturing for more than 11 years. Alex is also a part owner of World Fabrication, and owns his own job shop called Madsen Machine and Design. Alex has spent countless hours perfecting his setup to improve his part times.

“It is certainly challenging to use little tools, but the key is to not get discouraged. You should plan on lots of trial and error; breaking tools is just a part of the game. You may buy ten end mills and break six, but once you dial one in it will last the rest of the job.

You should also make sure to put extra time and effort into understanding your machine when working on micromachining jobs. You need to know where there is any backlash or issues with the machine because with a tiny tool, even an extra .0003” cut can mean the end of your tool. When a difference of one tenth can make or break your job, you need to take your time and be extra careful with your machine, tool inspection, and programming before you hit run.”

Tip 4: Effort Pays Off – Long Hours Result in Shop Growth

Success isn’t earned overnight. That is especially true in the machining world. Becoming a good machinist takes a great deal of sacrifice, says Josh from Fleet Machine Co. in Gloucester, MA.

“Opening your own shop involves more than learning how to program and machine. You also need to be willing to sacrifice some of your free time by working long hours to build your business from the ground up. Being a great machinist is important, but you also need to understand the basics of business, and you need to be able to sell your service and maintain a certain level of quality to keep your customers coming back.”

Working hard is a common theme we hear from our featured customers. Brothers Geordan and Nace Roberts of Master Machine Manufacturing have similar advice.

“We often need to work odd hours of the day to maintain the business, but we do it in a way that makes sure we have our family time. There are many times where we will go home, have dinner and hang out with the family, and wait until they are all sleeping to go back to work until two or three a.m. We will get back home later that morning to sleep a little and have breakfast with the family and send them on their way before heading back into the shop.” Starting and growing a business takes time. Every machinist starts from the beginning and through hard work and determination, grows their business.

Image courtesy of Liberty Machine Inc.

Tip 5: Utilize Tooling from Quality Manufacturers – All Tooling Isn’t Created Equal

 

When it comes down to it, tooling is singlehandedly the biggest choice you will make as a machinist. Grant Hughson, manufacturing engineer at Weiss Watch Company who works as a manufacturing instructor in his spare time, reflected on the importance of tooling.

“Tool to tool accuracy and performance is vital in this business, especially with our extremely tight tolerances. High quality tools make sure that we get the same performance time after time without needing to scrap parts. This saves us valuable time and money.”

While opting for cheaper tooling can appear to be beneficial when just starting out, before long, machinists are losing time and money because of unpredictability. Jonathan from TL Technologies echoed this point, saying:

“We feel that if we invested so much in these high-end machining centers, it would be criminal to put insufficient tooling and holders into them. We found that by selecting the proper tool with the appropriate sciences behind it we have been able to create products with a cost per cut that is not only competitive, but required to stay current. By keeping the quality as high as possible on the part making side of things, we’ve insured as much ease and reliability into our downstream process as we could. Quality tooling also provides predictability and added safety into the workflow. High-quality carbide tooling is the lifeblood of the business.”

Additional Thoughts Regarding Boosting Your Machining Career With Tooling:

Don’t Cheap Out

  • “The additional cost is always worth the payoff in the end knowing that you have a tool that will produce quality parts and shave valuable minutes off your cycle times. The slightly higher cost of the Harvey/Helical product is small change compared to the long term cost savings associated with their performance” – Seth, Liberty Machine

Consistency is Key

  • “We know the performance we are going to get from the tools is consistent, and we can always rely on getting immaculate finishes. While using the Harvey Tool and Helical product, we can confidently walk away from the machine and come back to a quality finished part every time.” – Bennett, RIT Baja SAE

Superior Specialty Tools

  • “One of the greatest things that I’ve experienced over the past year and a half is flexibility. We’ve asked for some specific tools to be made typically, the lead times that we found were beyond what we needed. We went through the Helical specials division and had them built within a couple of weeks. That was a game changer for us.” – Tom, John Force Racing

“Having high quality tooling like Helical is essential. Helical tools help us maintain a much higher machining efficiency because of the outstanding tool life, while also achieving more aggressive run times. In addition, we are able to consistently keep high tolerances, resulting in a better final product.” – Cameron, Koenig Knives

Tip 6: Get With the Times – Join the Social Media Community

Social media is a valuable tool for machinists. With ever-increasing popularity in networks such as Facebook, LinkedIn, Twitter, and Instagram, there will always be an audience to showcase new and unique products to. We asked a few of our featured customers how they incorporated social media into their machining and the benefits that come along with it.

“A lot of our sales come through Instagram or Facebook, so I would recommend those platforms to anyone who is trying to start a business,” Jeff from Okluma said. “We have also had a lot of success collaborating with others in the community. Typically it is something we couldn’t do ourselves, or they couldn’t do themselves, so we share the labor and collaborate on some really cool items.”

Tip 7: Value Your Customers – Always Put Them First

“In the Loupe’s” featured customers repeatedly emphasized the importance of putting customers first. It’s a simple concept to master, and pays off immensely. Repeat customers tell you that you are doing something right, said Brian Ross, owner of Form Factory.

“We have kept our customers happy and consistently deliver parts on time, so we get a lot of repeat business. Word definitely gets around on how you treat people so we try to treat everyone with respect and honesty which is key to running a good business.” Jeff from Okluma takes great pride in his customer service, saying “we only sell direct to consumers through our website so we can control our lifetime warranty. It has worked really well for us so far, so we have no plans to change that right now. I care more about our customers than any retailer is able to.”

Image courtesy of MedTorque.

Tip 8: Never Stop Learning – Ask Questions Whenever You Can

Hopefully some of these tips from our featured customers stuck with you. To leave you with a quote from of Seth Madore, owner of Liberty Machine, “Don’t stop learning. Keep your ears open and your mouth shut,” “That old guy in the shop has likely forgotten more than you will ever learn. The amount of tools in your Kennedy box doesn’t mean you’re a good machinist. Some of the best toolmakers I knew had small boxes with only the common tools. Learn how to excel with limited resources. Ask questions, and own up to your mistakes.”

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.

 

Effective Ways To Reduce Heat Generation

Any cutting tool application will generate heat, but knowing how to counteract it will improve the life of your tool. Heat can be good and doesn’t need to totally be avoided, but controlling heat will help prolong your tool life. Sometimes, an overheating tool or workpiece is easy to spot due to smoke or deformation. Other times, the signs are not as obvious. Taking every precaution possible to redirect heat will prolong your tool’s usable life, avoid scrapped parts, and will result in significant cost savings.

Reduce Heat Generation with HEM Tool Paths

High Efficiency Milling (HEM), is one way a machinist should explore to manage heat generation during machining. 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). HEM uses RDOC and ADOC similar to finishing operations but increases speeds and feeds, resulting in greater material removal rates (MRR). This technique is usually used for removing large amounts of material in roughing and pocketing applications. HEM utilizes the full length of cut and more effectively uses the full potential of the tool, optimizing tool life and productivity. You will need to take more radial passes on your workpiece, but using HEM will evenly spread heat across the whole cutting edge of your tool, instead of building heat along one small portion, reducing the possibility of tool failure and breakage.

heat generation

Chip Thinning Awareness

Chip thinning occurs when tool paths include varying radial depths of cut, and relates to chip thickness and feed per tooth. HEM is based off of the principal of chip thinning. However, if not properly executed, chip thinning can cause a lot of heat generation. When performing HEM, you effectively reduce your stepover and increase your speeds and feeds to run your machine at high rates. But if your machine isn’t capable of running high enough speeds and feeds, or you do not adjust accordingly to your reduced stepover, trouble will occur in the form of rubbing between the material and tool. Rubbing creates friction and mass amounts of heat which can cause your material to deform and your tool to overheat. Chip thinning can be good when used correctly in HEM, but if you fall below the line of reduced stepover without higher speeds and feeds, you will cause rubbing and tool failure. Because of this, it’s always important to be aware of your chips during machining.

heat generation

Consider Climb Milling

There are two ways to cut materials when milling: conventional milling and climb milling. The difference between the two is the relationship of the rotation of the cutter to the direction of feed. In climb milling, the cutter rotates with the feed, as opposed to conventional milling where the cutter rotates against the feed.

When conventional milling, chips start at theoretical zero and increase in size, causing rubbing and potentially work hardening. For this reason, it’s usually recommended for tools with higher toughness or for breaking through case hardened materials.

In climb milling, the chip starts at maximum width and decreases, causing the heat generated to transfer into the chip instead of the tool or workpiece. When going from max width to theoretical zero, heat will be transferred to the chip and pushed away from the workpiece, reducing the possibility of damage to the workpiece. Climb milling also produces a cleaner shear plane which will cause less tool rubbing, decreasing heat and improving tool life. When climb milling, chips are removed behind the cutter, reducing your chances of re-cutting. climb milling effectively reduces heat generated to the tool and workpiece by transferring heat into the chip, reducing rubbing and by reducing your chances of re-cutting chips.

 

heat generation

Utilize Proper Coolant Methods

If used properly, coolant can be an extremely effective way to keep your tool from overheating. There are many different types of coolant and different ways coolant can be delivered to your tool. Coolant can be 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.

Different applications and tools require different types and delivery of coolant, as using the wrong delivery or type could lead to part or tool damage. For instance, using high pressure coolant with miniature tooling could lead to tool breakage. In materials where chip evacuation is a major pain point such as aluminum, coolant is often used to flush chips away from the workpiece, rather than for heat moderation. When cutting material that produces long, stringy chips without coolant, you run the risk of creating built-up edge from the chips evacuating improperly. Using coolant will allow those chips to slide out of your toolpath easily, avoiding the chance of re-cutting and causing tool failure. In materials like titanium that don’t transfer heat well, proper coolant usage can prevent the material from overheating. With certain materials, however, thermal shock becomes an issue. This is when coolant is delivered to a very hot material and decreases its temperature rapidly, impacting the material’s properties. Coolant can be expensive and wasteful if not necessary for the application, so it’s important to always make sure you know the proper ways to use coolant before starting a job.

Importance of Controlling Heat Generation

Heat can be a tool’s worst nightmare if you do not know how to control it. High efficiency milling will distribute heat throughout the whole tool instead of one small portion, making it less likely for your tool to overheat and fail. By keeping RDOC constant throughout your toolpath, you will decrease the chances of rubbing, a common cause of heat generation. Climb milling is the most effective way to transfer heat into the chip, as it will reduce rubbing and lessen the chance of re-chipping. This will effectively prolong tool life. Coolant is another method for keeping temperatures moderated, but should be used with caution as the type of coolant delivery and certain material properties can impact its effectiveness.

Get to Know Machining Advisor Pro

Machining Advisor Pro (MAP) is a tool to quickly, seamlessly, and accurately deliver recommended running parameters to machinists using Helical Solutions end mills. This download-free and mobile-friendly application takes into account a user’s machine, tool path, set-up, and material to offer tailored, specific speeds and feed parameters to the tools they are using.

How to Begin with Machining Advisor Pro

This section will provide a detailed breakdown of Machining Advisor Pro, moving along step-by-step throughout the entire process of determining your tailored running parameters.

Register Quickly on Desktop or Mobile

To begin with Machining Advisor Pro, start by accessing its web page on the Harvey Performance Company website, or use the mobile version by downloading the application from the App Store or Google Play.

Whether you are using Machining Advisor Pro from the web or your mobile device, machinists must first create an account. The registration process will only need to be done once before you will be able to log into Machining Advisor Pro on both the mobile and web applications immediately.

machining advisor pro

Simply Activate Your Account

The final step in the registration process is to activate your account. To do this, simply click the activation link in the email that was sent to the email address used when registering. If you do not see the email in your inbox, we recommend checking your spam folders or company email filters. From here, you’re able to begin using MAP.

Using MAP

A user’s experience will be different depending on whether they’re using the web or mobile application. For instance, after logging in, users on the web application will view a single page that contains the Tool, Material, Operation, Machine, Parameter, and Recommendation sections.

 

 

On the mobile application, however, the “Input Specs” section is immediately visible. This is a summary of the Tool, Material, Operation, and Machine sections that allow a user to review and access any section. Return to this screen at any point by clicking on the gear icon in the bottom left of the screen.

machining advisor pro

Identify Your Helical Tool

To get started generating your running parameters, specify the Helical Solutions tool that you are using. This can be done by entering the tool number into the “Tool #” input field (highlighted in red below). As you type the tool number, MAP will filter through Helical’s 4,800-plus tools to begin identifying the specific tool you are looking for.

 

Once the tool is selected, the “Tool Details” section will populate the information that is specific to the chosen tool. This information will include the type of tool chosen, its unit of measure, profile, and other key dimensional attributes.

 

Select the Material You’re Working In

Once your tool information is imported, the material you’re working in will need to be specified. To access this screen on the mobile application, either swipe your screen to the left or click on the “Material” tab seen at the bottom of the screen. You will move from screen to screen across each step in the mobile application by using the same method.

In this section, there are more than 300 specific material grades and conditions available to users. The first dropdown menu will allow you to specify the material you are working in. Then, you can choose the subgroup of that material that is most applicable to your application. In some cases, you will also need to choose a material condition. For example, you can select from “T4” or “T6” condition for 6061 Aluminum.

 

Machining Advisor Pro provides optimized feeds and speeds that are specific to your application, so it is important that the condition of your material is selected.

Pick an Operation

The next section of MAP allows the user to define their specific operation. In this section, you will define the tool path strategy that will be used in this application. This can be done by either selecting the tool path from the dropdown menu or clicking on “Tool Path Info” for a visual breakdown and more information on each available toolpath.

 

Tailor Parameters to Your Machine’s Capabilities

The final section on mobile, and the fourth web section, is the machine section. This is where a user can define the attributes of the machine that you are using. This will include the Max RPM, Max IPM, Spindle, Holder, and work holding security. Running Parameters will adjust based on your responses.

 

Access Machining Advisor Pro Parameters

Once the Tool, Material, Operation, and Machine sections are populated there will be enough information to generate the initial parameters, speed, and feed. To access these on the mobile app, either swipe left when on the machine tab or tap on the “Output” tab on the bottom menu.

 

Please note that these are only initial values. Machining Advisor Pro gives you the ability to alter the stick out, axial depth of cut, and radial depth of cut to match the specific application. These changes can either be made by entering the exact numeric value, the % of cutter diameter, or by altering the slider bars. You are now able to lock RDOC or ADOC while adjusting the other depth of cut, allowing for more customization when developing parameters.

The parameters section also offers a visual representation of the portion of the tool that will be engaged with the materials as well as the Tool Engagement Angle.

MAP’s Recommendations

At this point, you can now review the recommended feeds and speeds that Machining Advisor Pro suggests based on the information you have input. These optimized running parameters can then be further refined by altering the speed and feed percentages.

 

Machining Advisor Pro recommendations can be saved by clicking on the PDF button that is found in the recommendation section on both the web and mobile platforms. This will automatically generate a PDF of the recommendations, allowing you to print, email, or share with others.

Machining Advisor Pro Summarized

The final section, exclusive to the mobile application, is the “Summary” section. To access this section, first tap on the checkmark icon in the bottom menu. This will open a section that is similar to the “Input Specs” section, which will give you a summary of the total parameter outputs. If anything needs to change, you can easily jump to each output item by tapping on the section you need to adjust.

 

 

This is also where you would go to reset the application to clear all of the inputs and start a new setup. On the web version, this button is found in the upper right-hand corner and looks like a “refresh” icon on a web browser.

Contact Us

For the mobile application, we have implemented an in-app messaging service. This was done to give the user a tool to easily communicate any question they have about the application from within the app. It allows the user to not only send messages, but to also include screenshots of what they are seeing! This can be accessed by clicking on the “Contact Us” option in the same hamburger menu that the Logout and Help & Tips are found.

Click this link to sign up today!

Tips for Maintaining Tight Tolerances

In manufacturing large production runs, one of the biggest difficulties machinists experience is holding tooling to necessary tolerances in holes, walls, and threads. Typically, this is an iterative process that can be tedious and stressful, especially for inexperienced machinists. While each job presents a unique set of challenges, there are rules of thumb that can be followed to ensure that your part is living up to its accuracy demands.

What is a Tolerance?

A tolerance is an allowable amount of variation in a part or cutting tool that a dimension can fall within. When creating a part print, tolerances of tooling can’t be overlooked, as tooling tolerances can result in part variations. Part tolerances have to be the same, if not larger, than tool tolerances to ensure part accuracy.

Cutting tool tolerances are oftentimes applied to a tool’s most critical dimensions, such as Cutter Diameter, Length of Cut, Shank Diameter, and Overall Length. When selecting a cutting tool for a job, it’s critical to choose a brand that adheres to strict tolerance standards and reliable batch-to-batch consistency. Manufacturers like Harvey Tool and Helical Solutions prominently display tolerances for many critical tool dimensions and thoroughly inspect each tool to ensure that it meets the tolerances specified. Below is the table header for Harvey Tool’s line of Miniature End Mills – Square – Stub & Standard.

tolerances

Tolerances help to create repeatability and specificity, especially in an industry in which even a thousandth of an inch can make or break a final product. This is especially true for miniature tooling, where Harvey Tool is experienced in the designing and manufacturing of tooling as small as .001” in diameter.

How are Tolerances Used?

When viewing a tolerance, there’s an upper and lower dimension, meaning the range in which the dimension of the tool can stray – both above and below what its size is said to be. In the below example, a .030″ cutter diameter tool’s size range would be anywhere between .0295″ and .0305.”

tooling tolerance

Maintaining Tolerances in Holemaking Operations

Holes oftentimes mandate the tightest dimensional tolerances, as they generally are meant to align perfectly with a mating part. To maintain tolerances, start first by testing the runout of both your machine and your tool. This simple, yet often overlooked step can save machinists a great amount of time and frustration.

Spotting Drills

Spotting Drills allow for drills to have a very precise starting point, minimizing walking or straying from a desired path. This can be especially beneficial when machining irregular surfaces, where accessing a hole’s perfect location can be more difficult.

spotting drills

Reamers

Reaming is great for any very tight tolerance mandate, because many Miniature Reamers have much tighter tolerances than a drill. Harvey Tool’s Miniature Reamers, for example, have tolerances of +.0000″/-.0002. for uncoated options and +.0002″/-.0000″ for AlTiN coated tools. Reamers cut on their chamfered edge, removing a minimal amount of material within a hole with the ultimate goal of bringing it to size. Because the cutting edge of a reamer is so small, the tool has a larger core diameter and is thus a more rigid tool.

miniature reamers

Maintaining Tight Tolerances While Machining Walls

Be Wary of Deflection

Maintaining tolerances when machining walls is made difficult by deflection, or the curvature a tool experiences when a force is applied to it. Where an angle is appearing on a wall due to deflection, opt for a reached tool to allow for less deflection along the tool’s neck. Further, take more axial depths of cut and machine in steps with finishing passes to exert less pressure on the tool. For surface finish tolerances, a long fluted tool may be required to minimize evidence of a tool path left on a part. For more information on ways to minimize deflection, read Tool Deflection & Its Remedies.tool deflection

Corner Radius End Mills

Corner radius End Mills, because they do not feature a sharp edge, will wear slower than a square end mill would. By utilizing corner radius tooling, fracturing on the tool edge will be minimized, resulting in an even pressure distribution on each of the cutting edges. Because the sharper edge on a square tool is less durable and more prone to cracking because of the stress concentration on that point, a corner radius tool would be much more rigid and thus less susceptible to causing a tolerance variation. For this reason, it’s recommended to use a roughing tool with a corner radius profile and a finisher with a square profile for an edge tolerance. When designing a part and keeping manufacturing in mind, if there is a potential for a wall with a radius as opposed to a wall with a square edge, a wall with a radius allows for easier machineability and fewer tool changes.

Maintaining Tight Tolerances While Threading

Making threads to tolerance is all about chip evacuation. Evacuating chips is an issue commonly overlooked; If chips within a hole have not been removed before a threading operation, there could be interference in the tool tip that leads to vibration and chatter within a thread. This would decrease the continuity of the thread while also altering the points of contact. Discontinuity of a thread could be the difference between passing and failing a part, and because threading is typically the last application when machining to decrease damaging the threads, it also increases the likelihood of chips remaining within the hole from other applications.

Tolerances Summarized

If you continue to experience troubles maintaining tight tolerances despite this blog post, consult the Harvey Tool or Helical Solutions tech team, as the problem may exist outside of your machine. Temperature and humidity can vary how gummy a material is, and can lead to workpiece expansion and contraction. Additionally, the foundation of buildings can expand and contract due to outside temperature, which can result in upped runout and irregular vibration in a spindle.

Why You Should Stop Deburring By Hand

Deburring is a process in which sharp edges and burrs are removed from a part to create a more aesthetically pleasing final product. After milling, parts are typically taken off the machine and sent off to the Deburring Department. Here, the burrs and sharp points are removed, traditionally by hand. However, an operation that takes an hour by hand can be reduced to mere minutes by deburring parts right in the machine with high precision CNC deburring tools, making hand deburring a thing of the past.

High Precision Tools

Hand deburring tools often have a sharp hook-shaped blade on the end, which is used to scrape/slice off the burrs as it passes along the edge of the part. These tools are fairly simple and easy to use, but much less efficient and precise than CNC deburring tools.

hand deburring

Image Source: https://upload.wikimedia.org/wikipedia/commons/0/03/Deburring_tool.jpg

CNC deburring tools are also held to much tighter tolerances than traditional hand-deburring tools. Traditional cylindrical deburring tools typically have a diameter-tolerance window of +/- .008 versus a CNC deburring end mill which has a diameter tolerance of +/-.0005. The tighter tolerance design eliminates the location issues found in traditional deburring tools with loose tolerances, allowing them to be programmed like a traditional end mill.

While hand deburring tools often have just a single blade, CNC deburring tools feature double cut patterns and a high number of flutes. The double cut pattern contains both right hand and left hand teeth, which results in an improved finish. These tools leave completed parts looking far superior to their hand-deburred counterparts, with more consistent and controlled edge breaks. Additionally, there is a large variety of CNC deburring tools available today which can take full advantage of multi-axis machines and the most complex tool paths. For example, Harvey Tool’s 270° Undercutting End Mill is a great choice for multi-axis and more complex deburring options. Further, Deburring Chamfer Cutters are multi-use tools that can perform both chamfering and deburring accurately with no need for a tool change.

cnc deburring

Reduce Production Costs and Increase Profits

Having an entire department dedicated to deburring can be costly, and many smaller businesses may have pulled employees off other jobs to help with deburring, which hampers production. Taking employees off the deburring station and asking them to run more parts or man another department can help keep labor costs low while still increasing production rates.

cnc deburring

Stop Deburring By Hand and Increase Your Profits

By deburring right in the CNC machine, parts can be completed in one machining operation. The double-cut pattern found on many deburring tools also allows for increased speeds and feeds. This helps to reduce cycle times even further, saving hours of work and increasing production efficiency. Deburring in the machine is a highly repeatable process that reduces overall cycle times and allows for more efficient finishing of a part. In addition, CNC machines are going to be more accurate than manual operations, leading to fewer scrapped parts due to human error and inconsistencies.

Simply put, the precision and accuracy of the CNC machine, along with the cost and time savings associated with keeping the part in the machine from start to finish, makes deburring in the CNC machine one of the easiest way to increase your shop’s efficiency.

Milling Machines vs. Lathe Machines

Most modern manufacturing centers have both milling machines and lathe machines. Each machine follows the same machining principle, known as subtractive machining, where you begin with a block of material and then shape that material into the desired specifications. How the part is actually shaped is the key difference between the two machines. Understanding the differences in more depth will help in putting the right part in the right machine to maximize their capabilities.

 

cnc lathe

An Example of a Lathe Machine

cnc milling machine

An Example of a Milling Machine

Operation

The major difference between a milling machine and a lathe machine is the relationship of the workpiece and the tool.

Lathe Machines

In a lathe, the workpiece that is being machined spins about it’s axis, while the cutting tool does not. This is referred to as “turning”, and is effective for creating cylindrical parts. Common operations done on a lathe include drilling, boring, threading, ID and OD grooving, and parting. When looking to create quick, repeatable, and symmetrical cylindrical parts, the lathe machine is the best choice.

cnc lathe

Milling Machines

The opposite is true for milling machines. The tool in a milling machine rotates about its axis, while the workpiece does not. This allows the tool to approach the workpiece in many different orientations that more intricate and complex parts demand. If you can program it, you can make it in a milling machine as long as you have the proper clearance and choose the proper tooling.

milling machines

Best Practice

The best reason to use a milling machine for an upcoming project is the versatility. The tooling options for a milling machine are endless, with hundreds of available specialty cutting tools and various styles of end mills which make sure you are covered from start to finish on each job. A mill can also cut more complex pieces than a lathe. For example, it would impossible to efficiently machine something like an intake manifold for an engine on a lathe. For intricate parts like that, a milling machine would be required for successful machining.

While lathe machines are more limited in use than a milling machine, they are superior for cylindrical parts. While a mill can make the same cuts that a lathe does, it may need multiple setups to create the same part. When continuous production of cylindrical parts is necessary, a lathe will outperform the mill and increase both performance and efficiency.

8 Ways You’re Killing Your End Mill

1. Running It Too Fast or Too Slow

Determining the right speeds and feeds for your tool and operation can be a complicated process, but understanding the ideal speed (RPM) is necessary before you start running your machine. Running a tool too fast can cause suboptimal chip size or even catastrophic tool failure. Conversely, a low RPM can result in deflection, bad finish, or simply decreased metal removal rates. If you are unsure what the ideal RPM for your job is, contact the tool manufacturer.

2. Feeding It Too Little or Too Much

Another critical aspect of speeds and feeds, the best feed rate for a job varies considerably by tool type and workpiece material. If you run your tool with too slow of a feed rate, you run the risk of recutting chips and accelerating tool wear. If you run your tool with too fast of a feed rate, you can cause tool fracture. This is especially true with miniature tooling.

3. Using Traditional Roughing

high efficiency milling

While traditional roughing is occasionally necessary or optimal, it is generally inferior to High Efficiency Milling (HEM). HEM is a roughing technique that uses a lower Radial Depth of Cut (RDOC) and a higher Axial Depth of Cut (ADOC). This spreads wear evenly across the cutting edge, dissipates heat, and reduces the chance of tool failure. Besides dramatically increasing tool life, HEM can also produce a better finish and higher metal removal rate, making it an all-around efficiency boost for your shop.

4. Using Improper Tool Holding

tool holding

Proper running parameters have less of an impact in suboptimal tool holding situations. A poor machine-to-tool connection can cause tool runout, pullout, and scrapped parts. Generally speaking, the more points of contact a tool holder has with the tool’s shank, the more secure the connection. Hydraulic and shrink fit tool holders offer increased performance over mechanical tightening methods, as do certain shank modifications, like Helical’s ToughGRIP shanks and the Haimer Safe-Lock™.

5. Not Using Variable Helix/Pitch Geometry

variable helix

A feature on a variety of high performance end mills, variable helix, or variable pitch, geometry is a subtle alteration to standard end mill geometry. This geometrical feature ensures that the time intervals between cutting edge contact with the workpiece are varied, rather than simultaneous with each tool rotation. This variation minimizes chatter by reducing harmonics, which increases tool life and produces superior results.

6. Choosing the Wrong Coating

end mill coatings

Despite being marginally more expensive, a tool with a coating optimized for your workpiece material can make all the difference. Many coatings increase lubricity, slowing natural tool wear, while others increase hardness and abrasion resistance. However, not all coatings are suitable to all materials, and the difference is most apparent in ferrous and non-ferrous materials. For example, an Aluminum Titanium Nitride (AlTiN) coating increases hardness and temperature resistance in ferrous materials, but has a high affinity to aluminum, causing workpiece adhesion to the cutting tool. A Titanium Diboride (TiB2) coating, on the other hand, has an extremely low affinity to aluminum, and prevents cutting edge build-up and chip packing, and extends tool life.

7. Using a Long Length of Cut

optimal length of cut

While a long length of cut (LOC) is absolutely necessary for some jobs, especially in finishing operations, it reduces the rigidity and strength of the cutting tool. As a general rule, a tool’s LOC should be only as long as needed to ensure that the tool retains as much of its original substrate as possible. The longer a tool’s LOC the more susceptible to deflection it becomes, in turn decreasing its effective tool life and increasing the chance of fracture.

8. Choosing the Wrong Flute Count

flute count

As simple as it seems, a tool’s flute count has a direct and notable impact on its performance and running parameters. A tool with a low flute count (2 to 3) has larger flute valleys and a smaller core. As with LOC, the less substrate remaining on a cutting tool, the weaker and less rigid it is. A tool with a high flute count (5 or higher) naturally has a larger core. However, high flute counts are not always better. Lower flute counts are typically used in aluminum and non-ferrous materials, partly because the softness of these materials allows more flexibility for increased metal removal rates, but also because of the properties of their chips. Non-ferrous materials usually produce longer, stringier chips and a lower flute count helps reduce chip recutting. Higher flute count tools are usually necessary for harder ferrous materials, both for their increased strength and because chip recutting is less of a concern since these materials often produce much smaller chips.