Tag Archive for: HEM toolpaths

Aspex CNC – Featured Customer

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Featured Image Courtesy of Aspex Cnc

Aspex CNC is a CNC machine shop based out of Poway, California. They offer prototype turning and milling, as well as production level machining. Their quick turnaround times and premium quality have garnered them some serious recognition in the manufacturing industry. Aspex CNC is just one of the four businesses that Gary Colle Jr. currently owns, but they are an essential part of his business ecosystem, creating parts for the other three product-based companies while also offering machining services to outside customers.

We talked to Gary about his unique experiences in the industry, his thoughts on 5 axis machining, his advice for trying High Efficiency Milling, and more!

Tell us a bit about how you got started in machining, your businesses, and how Aspex CNC was formed.

It is a bit of an interesting story. I got started in manufacturing because my father designed, developed, and manufactured one of the first lines of Wheelchair Accessible Vehicle lifts, which allow people in wheelchairs to easily get in and out of their vehicles. The company was called GoldenBoy Mobility and is still one of the four business I currently own and operate today.

At a young age, I was working in my father’s shop, answering phones and doing odd jobs as young as the age of 10. When I got to high school, I worked after school and during the summers in a more hands-on position, welding parts, cutting up cars, and helping on the shop floor. This really inspired my love for metalworking at a young age.

goldenboy mobility

Photo Courtesy of: Aspex CNC

My dad used to let me mess around in the shop at night, so I started welding my own parts and trying to learn as much as I could. One day, someone came in and asked if I could create a “tuna tower” (an accessory for wakeboarding/water skiing) for their boat. I relented at first, but eventually gave in and welded all the parts together for him. After I made that one, word got around that I could create these at night. I started to advertise a little bit locally, and people started ordering more and more. That summer, I ended up making 50 of these towers and got noticed by a couple of big distributors. Scaling up like that made it necessary to outsource some of our parts to local machine shops, which is where I discovered machining. I had very little prior knowledge of machining, but once I stepped into my first machine shop, I was blown away.

As that business grew even larger (now known as DBG Concepts), I needed more parts and needed them faster. We outgrew the local shops and purchased our first machine, a Fadal 4020 CNC Mill, from a local machine salesman, who also helped teach me the ropes. I learned a lot in those first 6 months about machining.

Business kept ramping up, and my father eventually retired and I took over GoldenBoy Mobility. With all the extra parts we needed, we kept machining things in-house, and buying more mills. Eventually, machining became an even larger part of the business than either DBG Concepts or GoldenBoy Mobility, so we formed Aspex CNC to move our machining out of the product line and more into prototype work and production machining for other business. We still machine most of the parts for DBG and GoldenBoy in-house, but we are doing much more for outside sources than we used to.

What sort of machines do you use in your shop?

Right now, we are a Haas-only shop. We currently have eight Haas machines in our shop. Our lineup consists of a couple of lathes (ST10 and ST30), a Super Mini Mill, and five CNC Mills (VF2SS, VF2SSYT, VF4SS, VF5SS, and UMC750SS), with another UMC750 on the way!

aspex cnc

Photo Courtesy of: Aspex CNC

Which materials do you most often work with in your shop?

We work with a lot of the common materials, 6061/7075 Aluminum, 1018/1045 Steel, 303/304/17-4ph Stainless, as well as plastics like Acetal, UHMW, HDPE, and PVC.

How has your experience been with 5 axis machining?

If you don’t keep up with technology, you won’t be able to keep up with business, so learning multi-axis machining was a no-brainer for us. We first started with a Haas HRT210 4th axis rotary, and began to play with that. Over the next two years, we learned everything we could about multi-axis machining and made the decision to upgrade to a 5 axis machine. We actually went to IMTS that year to talk to manufacturers and find the perfect machine for us and ended up sticking with Haas because of their support platform and educational resources.

5 axis can be hard, but there are a lot of tools out there (HSM Works from Autodesk being one) that can help you learn. It does require a little more upfront work and discipline, but it eliminates a lot of setup time, creates new opportunities for our shop, and has been really good for us from a business standpoint. A big part of our business is machining one-off parts, so the 5 axis machine allows for a faster turnaround time for those odd shapes and sizes we come across.

5 axis machining

Photo Courtesy of: Aspex CNC

You are very active on social media promoting your business. How has the online machinist community helped your business?

Honestly, even though it can become a bit of a distraction at times, using social media to share our work and partner up with companies like Harvey Tool and Helical has been a lot of fun. We are still young in the social media space, so we haven’t seen a massive impact yet, but the best is yet to come. We have received a few bites here and there which has led to work, but as with everything, it takes some time. We expect a lot of growth this year as we work on more really neat projects and continue to get our name out there. As we grow, the opportunities are going to come.

aspex cnc

Photo Courtesy of: Aspex CNC

What are some of the coolest projects you have ever worked on?

Unfortunately, we can’t talk about most of the work we do, due to customer confidentiality, but we did just do a project for the State of California building a training vehicle for their driver’s education program. We designed and built a dual steering system that gave the driver’s trainer a second steering wheel on the passenger side of the car to be used during training. Another job we just finished up was some parts for the new Raiders football stadium in Las Vegas. They contacted us in a pinch and needed them in two days, and we made it happen. It is pretty cool to know you played a part in a huge project like that.

Aspex CNC also does a lot of work with racing/off-road vehicle companies, often machining parts for the chassis and suspension components. We have worked on projects for companies like Scarbo Performance, ID Designs, TSCO Racing and a whole list of others.

You can only use one machine for the rest of your life. Do you go with a CNC Milling machine or the Lathe?

I would hate to have to choose between them, but it is 100% the CNC Mill. I love ripping around with end mills and working with the 5 axis machines. It is mind blowing what these things are capable of.

Why is manufacturing products in America important to you?

Growing up in the industry which I did while working under my father (building wheelchair accessible vehicles), we had a lot of customers who were veterans coming back from Vietnam or Desert Storm who had been injured overseas and needed extra accommodations, which we could provide for them. The veterans I have worked with made me so patriotic with their stories and courage. We also get to work on a lot of projects with the US Department of Veteran’s Affairs, which is putting money back into the American economy by supporting companies like ours and contracting us to make these vehicles. It only makes sense that we employ more people here and avoid sending things overseas to support those who have supported us.

aspex cnc

Photo Courtesy of: Aspex CNC

Do you utilize High Efficiency Milling (HEM) techniques in your shop? What advice do you have for those who are getting started with HEM?

Absolutely, all the time!

The biggest thing is listening to your tool manufacturer for recommendations and then cut those in half to start. From there, work your way up until you are comfortable. Just because the tool can handle it doesn’t necessarily mean your machine, work holding and or set up can, so I would advise people to walk before you run when it comes to HEM.

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

Be conservative and establish good habits from the start. You can get more aggressive as your career starts to take off, but don’t run out and try to run the biggest and baddest machines on day one and try to cut corners. You need to learn what is behind machining; you can get easily lost in all the technology that is available, but you need to understand the core science behind it first. Take it slow, because if you go too fast, you might miss something important along the way.

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

The best thing is building relationships with companies like Haas, Harvey Tool, and Helical. Not only do they provide great service and support for you, but it quickly becomes a mutually beneficial relationship. As we give feedback to the tool and machine manufacturers, and even our metal supplier, it helps them improve their products, which in turn allows our shop to increase our production and efficiency.

Also, having a good team with good people makes all the difference. No matter how many machines you have and how automated you get, you still need good people on your side. I would put my guys up against any other machine shop out there in terms of skill, and it is a big part of what has made our business so successful.

aspex cnc

Photo Courtesy of: Aspex CNC

Would you like to be considered for a future “Featured Customer” blog? Click here to submit your information.

8 Ways You’re Killing Your End Mill

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Running It Too Fast or Too Slow Can Impact Tool Life

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 to ensure proper tool life. 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.

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.

Using Traditional Roughing

infographic of traditional versus high efficiency milling depths of cut and heat generation

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.

Using Improper Tool Holding and its Effect on Tool Life

end mill held in haimer safe-lock tool holder

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™.

Not Using Variable Helix/Pitch Geometry

infographic showcasing intricacies variable helix end mill

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.

Choosing the Wrong Coating Can Wear on Tool Life

four different corner rounding end mills with different tool 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.

Using a Long Length of Cut

optimal length of cut for proper tool life

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.

Free Resource: Download the 50+ Page High Efficiency Milling (HEM) Guidebook Today

Choosing the Wrong Flute Count

infographic of face of end mills with varying flute counts

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.

Optimizing Material Removal Rates

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 What is the Material Removal Rate?

Material Removal Rate (MRR), otherwise known as Metal Removal Rate, is the measurement for how much material is removed from a part in a given period of time. Every shop aims to create more parts in a shorter period of time, or to maximize money made while also minimizing money spent. One of the first places these machinists turn is to MRR, which encompasses Radial Depth of Cut (RDOC), Axial Depth of Cut (ADOC), and Inches Per Minute (IPM) to create the MRR triangle where all three figures impact each other. If you’re aiming to boost your shop’s efficiency, increasing your MRR even minimally can result in big gains by decreasing cycle times and ultimately freeing up machines for increased productivity.

Click Here to Download the High Efficiency Milling (HEM) Guidebook

How to Calculate MRR In Machining

Material Removal Rate Formula

The Material Removal Rate equation is RDOC x ADOC x Feed Rate (IPM). As an example, if your RDOC is .500″, your ADOC is .100″ and your Feed Rate is 41.5 inches per minute, you’d calculate MRR the following way:

MRR = .500″ x .100″ x 41.5 in/min = 2.08 cubic inches per minute.

Infographic showcasing material removal rate equation

Optimizing Efficiency

A machinists’ depth of cut strategy is directly related to the Material Removal Rate. Using the proper RDOC and ADOC combination can boost MRR rates, shaving minutes off of cycle times and opening the door for greater production. Utilizing the right approach for your tool can also result in prolonged tool life, minimizing the rate of normal tool wear. Combining the ideal feed rate with your ADOC and RDOC to run at your tool’s “sweet spot” can pay immediate and long term dividends for machine shops.

The following MRR machining chart illustrates how a 1/2″, 5-flute tool will perform in Steel when varying ADOC and RDOC parameters are used. You can see that by varying the ADOC and RDOC, a higher feed rate is achievable, and thus, a higher MRR. In this case, pairing a high ADOC, low RDOC approach with an increased feed rate was most beneficial. This method has become known as High Efficiency Milling.

Axial Depth of CutRadial Depth of CutFeed RateMaterial Removal Rate
 .125″ .200″19.5 IPM .488 in.Âł/min.
.250″.150″26.2 IPM.983 in.Âł/min.
.500″.100″41.5 IPM2.08 in.Âł/min.
.750″.050″89.2 IPM3.35 in.Âł/min.
1.00″.025″193 IPM4.83 in.Âł/min.

High Efficiency Milling

High Efficiency Milling (HEM) is a milling technique for roughing that utilizes a lower RDOC and a higher ADOC strategy. This spreads wear evenly across the cutting edge, dissipates heat, and reduces the chance of tool failure. This results in a greater ability to increase your MRR in machining, while maintaining and even prolonging tool life versus traditional machining methods.

HEM VS Traditional Milling

The image referenced below compares the differences between traditional milling and the newer High Efficiency Milling technique in achieving adequate material removal. A traditional milling strategy requires the application of work and heat along a smaller portion of the cutting edge, while the HEM technique disperses heat more evenly across the entire cutting edge. This method calls for more radial passes which utilize a larger portion of the cutting edge, as opposed to axial passes that lead to a higher likelihood of tool failure over time.

infographic showcasing difference between traditional and hem depths of cut and heat generated

Obviously, with higher MRR’s, chip evacuation becomes vitally important as more chips are evacuated in a shorter period of time. Utilizing a tool best suited for the operation – in terms of quality and flute count – will help to alleviate the additional workload. For softer materials lower flute count tools will traditionally be the best choice. The thinner core allows for deeper flute valleys which aid in enhanced chip evacuation and ultimately increased MRR. On the other hand, harder materials require higher flute count tools with shallower flute valleys. This leads to less material removed per tooth, however tool life is substantially increased over the historic usage of lower flute count tools in these materials.

Additionally, a tool coating optimized for your workpiece material can significantly help with chip packing. First, tool coatings increase heat resistance of the tool allowing for faster cutting speeds leading to increased MRR. Secondly, coatings increase the lubricity of the cutting tool allowing for enhanced chip evacuation and lessened friction. This enhanced chip evacuation allows for the most efficient metal removal rate possible.

Further, compressed air or coolant can help to properly remove chips from the tool and workpiece. There are different three types of coolant delivery methods one could utilize in increasing metal removal rate.

Compressed Air

While having no lubricity purpose, the air coolant delivery method is made to cool and clear chips. This method does not cool as effectively as other coolant-based solutions, however it is preferred for more sensitive materials where thermal shock is a concern.

Flood

Flooding is a low pressure coolant delivery method which creates lubricity in order to evacuate chips from a part. This is necessary to prevent chip recutting which is likely to damage a cutting tool. This method of delivery is the most common choice for the widest range of machining operations.

High Pressure

This method is similar to flood coolant, however it is used to instantly cool a part and blast chips away with a high pressure of delivery. While highly effective at chip evacuation, this option is most likely to damage or break more fragile cutting tools. High pressure coolant delivery is most often utilized in deep pocket machining and drilling operations due to its increased ability to flush chips.

High efficiency milling guidebook ad

In conclusion, optimizing workplace efficiency is vital to sustained success and continued growth in every business. This is especially true in machine shops, as even a very minor adjustment in operating processes can result in a massive boost in company revenue. Proper machining methods will boost MRR, minimize cycle times, prolong tool life, and maximize shop efficiency.

Koenig Knives – Featured Customer

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Featured Image Courtesy of Koenig Knives

Koenig Knives is a fast-growing, Idaho-based knife manufacturer, recognized by many as one of the premier knife-making companies in the market today. Bill Koenig started the company back in 2013, using his off-days  in between his long shifts working the oil fields in North Dakota to build the business. After 3 years of exploring the craft, building a presence in the market, and saving money, Koenig was able to lease a work space, buy his first Haas machine, and start manufacturing his knives right here in America. The Koenig Knives team has now expanded to include four more employees: Krista, the Director of Operations, Cameron, the Lead Machinist, Doug in Assembly, and Todd, who works on finishing. Koenig Knives is quickly becoming known for their focus on quality, innovation, and consistency, backing all of their knives with a lifetime warranty.

We talked with both Bill and Cameron for this latest Featured Customer profile, exploring the world of CNC knifemaking, how they use High Efficiency Milling (HEM) to improve their machining efficiency, and the effect that the machining community on social media has had on their business.

koenig knives

Photo Courtesy of: Koenig Knives

Tell us about your business and how you got started.

Bill: Koenig Knives was started in 2013. I have always been passionate about knives, starting when I was in the Boy Scouts as a young boy. This passion turned to obsession and I went from a collector/enthusiast to a knife manufacturer in December of 2013 when we released our first batch of knives.

Originally we used an off-site manufacturer, who we worked closely with from 2013 until mid-2016. We continued to grow rapidly, and that is when I made the decision to start handling all manufacturing ourselves. We took delivery of our first machine, a Haas VF2SS, at the end of 2016. The rest is history.

What made you get into machining?

Cameron: I started as a CNC operator at an assault rifle manufacturer. After seeing raw material being machined into a beautiful, functioning gun, I decided to make machining my career and I have never looked back.

What sort of machines do you use in your shop?

Cameron: We currently have two Haas VF2SS machines and an Okamoto.

Which materials do you work with in your shop?

Cameron: We work with wide range of materials, including Grade 5 Titanium, Timascus, Damascus, Carbon Fiber, Micarta, Tool Steel , 6061 Aluminum , CTS-XHP, CTS-204P, and 416 Stainless Steel.

helical chamfer mill

Photo Courtesy of: Koenig Knives

What sets Koenig Knives apart from the competition?

Bill: We are often asked what category we would place ourselves in, whether it be production, custom etc. I always hesitate when answering because I can’t think of a way to categorize Koenig Knives besides “high end production with custom offerings.” We have a high end production line, but we also offer the ability to order your own customized version of one of our knives. This is something that is not too common in the industry. Quality, customer service and innovation are our main goals as a company, and we feel we have done a great job hitting on all three.

What is the most challenging part of the knife-making machining process?

Cameron: I think what makes the machining process unique with our product is the fact that we use some of the most cutting edge steel alloys for our blades. It becomes more challenging because these steel alloys are constantly advancing. Finding the perfect harmony of machining parameters for some of the relatively newer steels can be a challenge at times.

Why is high quality tool performance important to you?

Cameron: When part finishes are extremely crucial and there’s a high quantity of parts needed, 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.

koenig knives

Photo Courtesy of: Koenig Knives

What is your favorite process to work on as a machinist?

Cameron: I love everything about this career, except cleaning the coolant tank. I could do without that…

Koenig Knives has a great Instagram following. Tell us more about how the machinist social media community has helped grow your business.

Cameron: The machinist social media community has helped us connect with various knife makers all over the world. We learn from each other by sharing techniques and helpful tips, and we inspire each other by sharing our creations online. The machinist community on Instagram has been great – we would recommend any business, even the smallest job shops, to take a look at starting their own accounts.

Why is manufacturing your products in America important to you?

Bill: Buying American has always been very important to me for many reasons. The sense of supporting fellow American workers was instilled in me at a young age.  When I started Koenig Knives, I wanted to make sure everything from the screws to the boxes was made in the US.

koenig knives

Photo Courtesy of: Koenig Knives

Tell us about your favorite project that Helical helped to create.

Cameron: Machining the Arius blades (pictured above) has been my favorite on-going project. Once we switched to all Helical tools, it drastically improved our run times and blade finish, and created an incredible final product.

Have you used High Efficiency Milling techniques in your shop?

Cameron: Absolutely! We couldn’t do without HEM!

What advice do you have for other machinists who want to try High Efficiency Milling?

Cameron: Machining Advisor Pro is an absolute game changer when it comes to HEM, as well as for general machining solutions. The technical milling strategies and information that Helical makes available give machinists everything they need to be successful. When a machinist has a full understanding of what is taking place and what is needed to efficiently and correctly cut material, the sky is the limit.

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

Cameron: 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.

koenig knives

Photo Courtesy of: Koenig Knives

Would you like to be considered for a future “Featured Customer” blog? Click here to submit your information.

Photos courtesy of Koenig Knives.

Why Flute Count Matters

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One of the most important considerations when choosing an end mill is determining which flute count is best for the job at hand. Both material and application play an important role in this critical part of the tool selection process. Understanding the effects of flute count on other tool properties, and how a tool will behave in different situations is an essential consideration in the tool selection process. As end mills have become more and more advanced, certain standards have been created for flute counts in certain materials. While there is obvious overlap due to a myriad of factors, proper flute count is critical for machining success and ensuring you are making the most of your end mill and it’s associated MRR.

Machining Advisor Pro (MAP) Takes Flute Count Into Consideration When Helping You Dial In Running Parameters.

Click Here to Get Started.

Tool Geometry Basics

Generally, tools with more flutes have a larger core and smaller flute valleys than tools with fewer flutes.  More flutes with a larger core can provide both benefits and restrictions depending on the application.  Simply put, a larger core is directly proportional to tool strength; the larger the core, the stronger a tool will be.  In turn, a larger core also reduces the flute depth of a tool, restricting the amount of space for chips to exist.  This can cause issues with chip packing in applications requiring heavy material removal.  However, these considerations only lead us part way when making a decision on which tool to use, and when.

3, 5, and 8 flute end mills and their core sizes in relation to flute valleys

Material Considerations

Traditionally, end mills came in either a 2 flute or 4 flute option.  The widely accepted rule of thumb was to use 2 flutes for machining aluminum and non-ferrous materials, and 4 flutes for machining steel and harder alloys.  As aluminum and non-ferrous alloys are typically much softer than steels, a tool’s strength is less of a concern, a tool can be fed faster, and larger material removal rates (MRR) is facilitated by the large flute valleys of 2 flute tools.

Consequently, ferrous materials are typically much harder, and require the strength of a larger core.  Feed rates are slower, resulting in smaller chips, and allowing for the smaller flute valleys of a larger core tool.  This also allows for more flutes to fit on the tool, which in turn increases productivity.

end mill flute count comparisons

Recently, with more advanced machines and toolpaths, higher flute count tools have become the norm in manufacturing.  Non-ferrous tooling has become largely centered on 3 flute tools. This has created a slight advantage over 2 flute tools by increasing productivity while still affording proper chip evacuation. The softness of non-ferrous materials affords a much deeper flute valley. As previously discussed, this allows the tool to be fed much faster than in ferrous materials. Adding an additional flute increases the productivity of the tool, while still affording machinists faster feed rates.

Ferrous tooling has taken a step further and progressed not only to 5 and 6 flutes, but up to 7 flutes and more in some cases.  With a wider range of hardness, sometimes at the very top of the Rockwell hardness scale, many more flutes have allowed longer tool life, less tool wear, stronger tools, and less deflection.  All of this results in more specialized tools for more specific materials. Material specific tooling combines proper flute counts with coatings that aid in lubricity and heat generation to ensure the most effective end mill possible in the material being machined. The end result is higher MRR and increased productivity across the entire range of ferrous materials that machinists will work with in their shops.

Running Parameters

Just as material considerations will have an impact on the tool you choose, operation type and depth of cut requirements may also have a big impact on the ideal number of flutes for your application.  In roughing applications, lower flute counts may be desirable to evacuate large amounts of chips faster with larger flute valleys.  That said, there is a balance to find, as modern toolpaths such as High Efficiency Milling (HEM) can achieve extreme MRR with a very small step over, and a higher number of flutes.  In a more traditional sense, higher flute counts are great for finishing operations where very small amounts of material are being removed, and greater finish can be achieved with more flutes, not worrying as much about chip evacuation as that phase has already been accomplished during roughing.

helical end mill with lines showcasing the flute valleys

Flute count plays a big role in speeds and feeds calculation as well.  One common rule of thumb is “more flutes, more feed,” but this can be a very detrimental misconception.  Although true in some cases, this is not an infinitely scalable principle.  As stated previously, increasing the number of flutes on a tool limits the size that the flute valleys can be.  While adding a 5th flute to a 4 flute tool theoretically gives you 25% more material removal per revolution with an appropriately increased feed rate, feeding the tool that much faster may overload the tool.  The 25% increase in material removal is more likely closer to 10-15%, given the tool is exactly the same in all other specifications.  Higher flute count tools may require speeds and feeds to be backed off so much in some cases, that a lower flute count may be even more efficient.  Finding the right balance is key in modern milling practices. Consulting a tooling manufacturer’s speeds and feeds will be the perfect starting point, and then machinists can make changes as they see fit to properly accomplish the job at hand.

In all, the importance of flute count identification is critical to continued success at the spindle. Different materials have different strength requirements as well as variability in how much material can be appropriately removed per tooth.

Harvey Performance Brands Announce Release of HEM Guidebook

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ROWLEY, MA (August 22, 2017) – Harvey Performance Company’s two brands, Harvey Tool and Helical Solutions, collaborated in the creation of the HEM Guidebook. This new resource centers around the concept of High Efficiency Milling (HEM), popular for its ability to boost shop productivity by minimizing cycle times and boosting tool performance.

Included within the HEM Guidebook are seven relevant articles: Introduction to High Efficiency Milling, High Speed Machining Vs. HEM, Combat Chip Thinning & Boost Tool Potential, Diving into Depth of Cut, Preventing Tool Wear, Applying HEM to Micromachining, and Best Practices for Trochoidal Milling. Additionally, HEM usage statistics and machinist tips for this popular machining method are included, and were gathered as part of a survey hosted by the two brands in the days preceding its release.

“We’re thrilled to present this helpful resource to the metalworking industry,” said Garth Ely, Harvey Performance Company Vice President of Marketing. “This machining method has results proven to enhance our customers’ shop performance, and we’re confident this resource will help them achieve the production benefits that HEM offers.”

Applying HEM to Micromachining

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The following is just one of several blog posts relevant to High Efficiency Milling and Micromachining. To achieve a full understanding of this popular machining method, view any of the additional HEM posts below!

Introduction to High Efficiency Milling I High Speed Machining vs. HEM I How to Combat Chip Thinning I Diving into Depth of Cut I How to Avoid 4 Major Types of Tool Wear I Intro to Trochoidal Milling

Benefits of Using HEM with Miniature Tooling

High Efficiency Milling (HEM) is a technique for roughing that utilizes a lower Radial Depth of Cut (RDOC), and a higher Axial Depth of Cut (ADOC). This delays the rate of tool wear, reducing the chance of failure and prolonging tool life while boosting productivity and Material Removal Rates (MRR). Because this machining method boosts MRR, miniature tooling (<.125”) and micromachining is commonly overlooked for HEM operations. Further, many shops also do not have the high RPM capabilities necessary to see the benefits of HEM for miniature tooling. However, if used properly, miniature tooling can produce the same benefits of HEM that larger diameter tooling can.

Benefits of HEM:

  • Extended tool life and performance.
  • Faster cycle times.
  • Overall cost savings

Preventing Common Challenges in Micromachining

Utilizing miniature tooling for HEM, while beneficial if performed correctly, presents challenges that all machinists must be mindful of. Knowing what to keep an eye out for is a pivotal first step to success.

small harvey tool end mill for micromachining on a penny showing size

Tool Fragility & Breakage with Miniature Tooling

Breakage is one of the main challenges associated with utilizing high efficiency micromachining with miniature tools due to the fragility of the tool. Spindle runout and vibration, tool deflection, material inconsistencies, and uneven loading are just some of the problems which can lead to a broken tool. To prevent this, more attention must be paid to the machine setup and material to ensure the tools have the highest chance of success.

As a general rule, HEM should not be considered when using tools with cutting diameters less than .031”. While possible, HEM may still be prohibitively challenging or risky at diameters below .062”, and your application and machine must be considered carefully.

Techniques to Prevent Tool Failure:

Managing Excessive Heat & Thermal Shock in Micromachining

Due to the small nature of miniature tooling and the high running speeds they require, heat generation can quickly become an issue. When heat is not controlled, the workpiece and tooling may experience thermal cracking, melting, burning, built up edge, or warping.

To combat high heat, coolant is often used to decrease the surface temperature of the material as well as aid in chip evacuation and lubricity. However, care must be taken to ensure that using coolant doesn’t cool the material too quickly or unevenly. If an improper coolant method is used, thermal shock can occur. Thermal shock happens when a material expands unevenly, creating micro fractures that propagate throughout the material and can crack, warp, or change the physical properties of the material.

end mill in the cut with external coolant being applied

Techniques to Prevent Heat & Thermal Shock:

Key Takeaways

If performed properly, miniature tooling micromachining (<.125”) can reap the same benefits of HEM that larger diameter tooling can: reduced tool wear, accelerated part production rates, and greater machining accuracy. However, more care must be taken to monitor the machining process and to prevent tool fragility, excessive heat, and thermal shock.

Check out this example of HEM toolpaths (trochoidal milling) being run with a 3/16″ Harvey Tool End Mill in aluminum.

Introduction to High Efficiency Milling

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The following is just one of several blog posts relevant to High Efficiency Milling. To achieve a full understanding of this popular machining method, view any of the additional HEM posts below!

High Speed Machining vs. HEM I How to Combat Chip Thinning I Diving into Depth of Cut I How to Avoid 4 Major Types of Tool Wear I Intro to Trochoidal Milling

High Efficiency Milling (HEM) is a strategy that is rapidly gaining popularity in the metalworking industry. Most CAM packages now offer modules to generate HEM toolpaths, each with their own proprietary name. In these packages, HEM can also be known as Dynamic Milling or High Efficiency Machining, among others. HEM can result in profound shop efficiency, extended tool life, greater performance, and cost savings. High performance end mills designed to achieve higher speeds and feeds will help machinists to reap the full benefits of this popular machining method.

High Efficiency Milling Defined

HEM is a milling technique for roughing that utilizes 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.

This strategy differs from traditional or conventional milling, which typically calls for a higher RDOC and lower ADOC. Traditional milling causes heat concentrations in one small portion of the cutting tool, expediting the tool wear process. Further, while Traditional Milling call for more axial passes, HEM toolpaths use more passes radially.

For more information on optimizing Depth of Cut in relation to HEM, see Diving into Depth of Cut: Peripheral, Slotting & HEM Approaches.

infographic examining depth of cut differences between HEM and traditional milling

Built-In CAM Applications

Machining technology has been advancing with the development of faster, more powerful machines. In order to keep up, many CAM applications have developed built-in features for HEM toolpaths, including Trochoidal Milling, a method of machining used to create a slot wider than the cutting tool’s cutting diameter.

HEM is largely based on the theory surrounding Radial Chip Thinning, or the phenomenon that occurs with varying RDOC, and relates to the chip thickness and feed per tooth. HEM adjusts parameters to maintain a constant load on the tool through the entire roughing operation, resulting in more aggressive material removal rates (MRR). In this way, HEM differs from other high performance toolpaths, which involve different methods for achieving significant MRR.

Click Here to learn More About The Efficiency-Boosting Power of High Efficiency Milling

Virtually any CNC machine can perform HEM – the key is a fast CNC controller. When converting from a regular program to HEM, about 20 lines of HEM code will be written for every line of regular code. A fast processor is needed to look ahead for the code, and keep up with the operation. In addition, advanced CAM software that intelligently manages tool load by adjusting the IPT and RDOC is also needed.

High Efficiency Milling Case Studies

The following example shows the result a machinist had when using a Helical Solutions HEV-5 tool to perform an HEM operation in 17-4PH stainless steel. While performing HEM, this ½” diameter, 5-flute end mill engaged the part just 12% radially, but 100% axially. This machinist was able to reduce tool wear and was able to complete 40 parts with a single tool, versus only 15 with a traditional roughing toolpath.

traditional roughing vs HEM comparison chart

The effect of HEM on a roughing application can also be seen in the case study below. While machining 6061 aluminum with Helical’s H45AL-C-3, a 1/2″, 3-flute rougher, this machinist was able to finish a part in 3 minutes, versus 11 minutes with a traditional roughing toolpath. One tool was able to make 900 parts with HEM, a boost of more than 150% over the traditional method.

traditional roughing vs HEM comparison chart

Importance of Tooling to HEM

Generally speaking, HEM is a matter of running the tool – not the tool itself. Virtually every tool can perform HEM, but using tooling built to withstand the rigors of HEM will result in greater success. While you can run a marathon in any type of shoes, you’d likely get the best results and performance from running shoes.

HEM is often regarded as a machining method for larger diameter tooling because of the aggressive MRR of the operation and the fragility of tooling under 1/8” in size. However, miniature tooling can be used to achieve HEM, too.

Using miniature tooling for HEM can create additional challenges that must be understood prior to beginning your operation.

Best Tools for HEM:

  • High flute count for increased MRR.
  • Large core diameter for added strength.
  • Tool coating optimized for the workpiece material for increased lubricity.
  • Variable Pitch/Variable Helix design for reduced harmonics.

Key Takeaways

HEM is a machining operation which continues to grow in popularity in shops worldwide. A milling technique for roughing that utilizes a lower RDOC and higher ADOC than traditional milling, HEM distributes wear evenly across the cutting edge of a tool, reducing heat concentrations and slowing the rate of tool wear. This is especially true in tooling best suited to promote the benefits of HEM.

High Speed Machining vs. HEM

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The following is just one of several blog posts relevant to High Efficiency Milling and High Speed Machining. To achieve a full understanding of this popular machining method, view any of the additional HEM posts below!

Introduction to High Efficiency Milling I How to Combat Chip Thinning I Diving into Depth of Cut I How to Avoid 4 Major Types of Tool Wear I Intro to Trochoidal Milling

Advancements in the metalworking industry have led to new, innovative ways of increasing productivity. One of the most popular ways of doing so (creating many new buzzwords in the process) has been the discovery of new, high-productivity toolpaths. Terms like trochoidal milling, high speed machining, adaptive milling, feed milling, and High Efficiency Milling are a handful of the names given to these cutting-edge techniques.

With multiple techniques being described with somewhat similar terms, there is some confusion as to what each is referring to. High Efficiency Milling (HEM) and High Speed Machining (HSM) are two commonly used terms and techniques that can often be confused with one another. Both describe techniques that lead to increased material removal rates and boosted productivity.  However, the similarities largely stop there.

High Speed Machining

High speed machining is often used as an umbrella term for all high productivity machining methods including HEM. However, HEM and HSM are unique, separate machining styles. HSM encompasses a technique that results in higher production rates while using a much different approach to depth of cut and speeds and feeds. While certain HEM parameters are constantly changing, HSM uses constant values for the key parameters. A very high spindle speed paired with much lighter axial depths of cut results in a much higher allowable feed rate. This is also often referred to as feed milling. Depths of cut involve a very low axial and high radial components. The method in general is often thought of as z-axis slice machining, where the tool will step down a fixed amount, machine all it can, then step down the next fixed amount and continue the cycle.

High speed machining techniques can also be applied to contoured surfaces using a ball profile or corner radius tool. In these situations, the tool is not used in one plane at a time, and will follow the 3 dimensional curved surfaces of a part. This is extremely effective for using one tool to bring a block of material down to a final (or close to final) shape using high resultant material removal rates paired with the ability to create virtually any shape.

High Efficiency Milling

HEM has evolved from a philosophy that takes advantage of the maximum amount of work that a tool can perform. Considerations for chip thinning and feed rate adjustment are used so that each cutting edge of a tool takes a consistent chip thickness with each rotation, even at varying radial depths of cut and while interpolating around curves. This allows machinists the opportunity to utilize a radial depth of cut that more effectively uses the full potential of a given tool. Utilizing the entire available length of cut allows tool wear to be spread over a greater area, prolonging tool life and lowering production costs. Effectively, HEM uses the depths associated with a traditional finishing operation but boosts speeds and feeds, resulting in much higher material removal rates (MRR). This technique is typically used for hogging out large volumes of material in roughing and pocketing applications.

In short, HEM is somewhat similar to an accelerated finishing operation in regards to depth of cut, while HSM is more of a high feed contouring operation. Both can achieve increased MRR and higher productivity when compared to traditional methods. While HSM can be seen as an umbrella term for all high efficiency paths, HEM has grown in popularity to a point where it can be classified on its own. Classifying each separately takes a bit of clarification, showing they each have power in certain situations.

Check out the video below to see HEM in action!

https://www.instagram.com/p/BV7voCVB4Ah/?taken-by=helicaltools

Intro to Trochoidal Milling

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The following is just one of several blog posts relevant to High Efficiency Milling. To achieve a full understanding of this popular machining method, view any of the additional HEM posts below!

Introduction to High Efficiency Milling I High Speed Machining vs. HEM I How to Combat Chip Thinning I Diving into Depth of Cut I How to Avoid 4 Major Types of Tool Wear

What Is Trochoidal Milling?

Trochoidal milling is a method of machining used to create a slot wider than the cutting tool’s cutting diameter. This is accomplished using a series of circular cuts known as a trochoidal tool path. A form of High Efficiency Milling (HEM), trochoidal milling leverages high speeds while maintaining a low radial depth of cut (RDOC) and a high axial depth of cut (ADOC).

Trochoidal milling is largely based on the theory surrounding chip thinning in machining. Conventional thinking suggests that cutting tools have an optimal chip load that determines the ideal width and size of the chips produced. The concept of combating chip thinning involves machining with a chip load that is larger than “optimal” in order to maintain a constant maximum chip thickness.

In contrast to a completely linear radial tool path in conventional machining, trochoidal milling takes advantage of a spiral tool path with a low RDOC to reduce load and wear on the tool (Figure 1).

trochoidal milling toolpath displayed

Advantages of Trochoidal Milling

  • Decreased cutting forces
  • Reduced heat
  • Greater machining accuracy
  • Improved tool life
  • Faster cycle times
  • One tool for multiple slot sizes

Trochoidal milling can be very advantageous in certain applications. The reduced radial engagement of the cutting edge decreases the amount of heat produced in the cut while also decreasing the cutting forces and load on the spindle. The reduced radial forces allow for greater accuracy during production and make it possible to machine finer and more precise features on a part.

In addition, the lower radial depth of cut allows for a higher axial depth of cut, meaning that the entire length of the cutting edge can be utilized. This ensures that heat and cutting forces are distributed across the tool’s cutting edge, rather than concentrated on a single section. The reduced heat and wear, combined with their uniform spread on the cutting edge, resulting in significantly improved tool life over conventional slotting methods.

Given the reduced destructive forces, the cutting tool’s speeds can be increased. Since the entire length of cut is utilized, trochoidal milling can eliminate the need for multiple axial depths of cut. Increased running parameters and a reduced number of passes greatly reduce cycle time.

Since trochoidal milling uses a tool to machine a slot wider than its cutting diameter, the same tool can be used to create slots of varying sizes, rather than just one. This can free up space in your tool carousel and save time on tool change-outs, depending on the requirements of the part (Figure 2).

trochoidal milling paths of different sizes with same tool

Although slotting is a roughing operation, the reduced radial depth of cut and decreased cutting forces from trochoidal milling often result in an improved finish over a conventional slotting toolpath. However, a finishing pass along the walls of the workpiece might be required to remove any cusps left from the spiral motion of the cutting tool.

Click Here to Learn More About The Efficiency-Boosting Power of High Efficiency Milling

Challenges of Trochoidal Milling

The challenges of trochoidal milling are typically found with the machinery and software. The right machine to take advantage of trochoidal milling will not only be capable of high speeds and feeds but will also be capable of a constantly changing feed rate as the tool moves along it’s spiral path. Inability to have a changing feed rate will cause chip thinning which can yield non-ideal results and potentially cause tool breakage. Special software might also be required to program tool paths and feed rates for this process. This is further complicated by factors like the ratio of the cutter diameter to the size of the groove, as well as the radial depth of cut for these different ratios. Most figures suggest the cutter diameter be 50%-70% of the final slot width, while the radial depth of cut should equal 10%-35% of cutter diameter (Table 1), but the safest option is always to consult the tool manufacturer.

trochoidal milling diameter, depths of cut, and slot width chart

Trochoidal Milling and Micromachining

Benefits When Micromachining

Micromachining can also benefit from trochoidal milling. The decreased radial engagement and lower cutting forces produced during a trochoidal tool path put less force on the cutting tools. This is especially important for smaller diameter tools, as they are weaker and less rigid, and the reduced cutting forces decrease the chance of deflection and breakage.

Challenges When Micromachining

While trochoidal milling with miniature tooling is theoretically beneficial, there are additional challenges associated with smaller tools. Miniature cutting tools are much more susceptible to breakage due to spindle runout and vibration, material inconsistencies, uneven loading, and many other variables that arise during machining. Depending on your application, it may be worth using the tool with the greatest diameter for the extra strength. Although there are potential benefits at the miniature level, more attention must be paid to the machine setup and material to ensure the tools have the highest chance of success.

Just like HEM, as a general rule, trochoidal milling should not be considered when using tools with cutting diameters less than .031”. While possible, trochoidal milling may still be prohibitively challenging or risky at diameters below .062”, and your application and machine must be considered carefully.

Conclusion

Trochoidal milling is a High Efficiency Milling technique (high speed, high ADOC, low RDOC) characterized by a circular, or trochoidal, tool path. This milling style is proven to offer significant machining process benefits, such as increasing tool life, reducing machining times, and fewer tools required for a job. However, it is critical to have a machine and software capable of high speeds and feeds and constantly changing feed rates to avoid critical tool failure. While miniature tools can still benefit from trochoidal milling, the risk of tool breakage must be considered carefully, especially at cutter diameters below .062”. Although trochoidal milling can increase your machining efficiency in many applications, it is always a good idea to consult your tool manufacturer beforehand.

A great example of trochoidal milling in action can be seen in this video, where a 1/2″ Helical Solutions end mill with variable helix, variable pitch was used to machine a block of 316 stainless steel.

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