by Bernard Martin

Here are some basic rules of thumb on end mill selection

Navigating the vast array of end mills available in the market can be a daunting task, especially when precision is paramount. To aid in this process, we've outlined a step-by-step guide that addresses crucial considerations for selecting the optimal end mill for your machining needs.

Step 1 – Material Identification: Identify the exact material, its condition (billet, forging, etc.), and hardness (HRC). This information directs you to the Non-Ferrous or Ferrous section of our catalog.

Step 2 – Operation Type: Determine whether you'll be roughing, finishing, or both. This guides the choice of the number of flutes and the need for chip breakers.

Step 3 – Programming Style: Choose between traditional programming, high efficiency programming (HEM), or a combination. This decision influences the number of flutes (Step 8).

Step 4 – ADOC (Axial Depth of Cut): Determine the maximum axial depth of cut the tool will experience in the part. This information helps decide the length of cut (LOC) to deploy.

Step 5 – Reach Consideration: Evaluate obstacles to clear and depths to reach. If necessary, consider a reduced necked tool to maintain length of cut while reaching deeper positions.

Step 6 – Tool Diameter Selection: Consider the machine taper, cut depth, reach, and part geometry. Keeping the tool diameter under 3/4" for 40-taper machines and adapting the diameter to programming style, cut depth, and reach requirements.  Keep in mind  what programming style (Step 3) you’re using as HEM can employ smaller diameters than you may be used to. Decide on your cut depth (Step 4). For traditional programming keep it <2xDia., for HEM keep it below 4xDia.  Decide on your total reach depth (Step 5). If needing to machine 4xDia. look at a necked tool to maintain strength and minimize deflection.

​Step 7 – Corner Radius: Determine if your part requires a corner radius. Running a corner radius on an end mill can extend its life and is especially beneficial for pre-finishing.

Step 8 – Flute Count: Consider the material and programming type to determine the ideal flute count. Non-Ferrous machining typically requires 2-3 flutes for traditional programming and 3-5 for HEM, while Ferrous machining may need 4-5 for traditional programming and 5-7 for HEM.

Step 9 – Tool Holder Selection: Always opt for the most rigid and accurate tool holder with minimal runout. Keep the Total Indicator Runout (TIR) below 0.0005 at the tip of the tool for optimum tool life and success. Consider the use of a side lock holder for specific applications.

Remember, our team at Next Gen Tooling is always available to assist you in selecting the correct product. By following these guidelines, you'll navigate the selection process with confidence, ensuring precision and efficiency in your machining operations.

​7-Flute End Mills

• Advantages: Improved surface finish, particularly in finishing applications.
• Disadvantages: Limited chip clearance.
• Suitability: Specialized for finishing in softer materials (ISO P, M, S, H).

It is critical to properly assemble the collet and collet nut to avoid damage to the collet and make the most accurate and rigid assembly possible.

The extraction groove of the collet must be properly seated to the extraction ring of the collet nut.

If the collet extraction groove is not properly seated to the collet nut extraction ring, the collet will appear seated below the face of the nut.

This typically occurs when the collet is placed in the collet pocket of the tool holder and then the nut is threaded on the tool holder. In a correct assembly, the collet will seat at the face of the collet nut.

The image below shows a correct assembly on the left and an incorrect assembly on the right.

DO NOT tighten the collet nut if the collet appears seated below the face of the nut as this will create galling on the 30° face of the collet. Galling appear as grooves or lines in the lead face of the collet.

by Frank Twomey | OSG USA

Recently, Ross Industries was tasked with reducing cycle times on all of its aluminum parts. OSG Territory Sales Manager Frank Twomey has been in touch with Ross Industries through a distributor for about two years ago. In need to optimize productivity, OSG was given with an opportunity to test cut the upper chamber 6061 aluminum alloy part used in Ross Industries’ tray sealers for food packaging.

Ross Industries has been producing these aluminum upper chambers for more than 25 years. Approximately 80 chambers are made annually along with thousands of other aluminum parts. The upper chambers are machined using a Doosan HM 1000 horizontal machining center with CAT-50 spindle taper.

Ross Industries was originally using a competitor 1.5-inch diameter indexable shoulder cutter for the application. The competitor tool was used at a speed of 6,000 rpm (2,358 sfm, 717.8 m/min), a feed rate of 120 ipm (3,048 mm/min), 0.005 ipt (0.127 mm/t), 0.3-inch (7.62 mm) radial depth of cut, 0.375-inch (9.525 mm) axial depth of cut, and at a metal removal rate of 13.5 inch3/min (221.2 cm3/min).

Upon a detail evaluation of the application, Twomey recommended OSG’s 3-flute 1-inch diameter AE-TL-N DLC coated square end mill (EDP# 86301809).

​The AE-TL-N DLC coated carbide end mill is extremely effective for non-ferrous materials such as aluminum alloys that require welding resistance and lubricity. With excellent cutting sharpness, it is able to suppress burrs to achieve superb surface finish.

The AE-TL-N features a unique flute form to enable trouble-free chip evacuation and a large core design for high rigidity to prevent chattering. Its center cutting edge configuration enables the tool to be used for plunging. Furthermore, with the addition of OSG’s DLC-SUPER HARD coating, long tool life can be achieved. This end mill series is available in square, sharp corner edge and radius types to accommodate a wide range of applications.

The AE-TL-N DLC coated carbide end mill was tested at a speed of 5,125 rpm (1,343 sfm, 408.7 m/min), a feed rate of 231 ipm (5,867 mm/min), 0.015 ipt (0.382 mm/t), 0.14-inch (3.556 mm) radial depth of cut, 1.62-inch (41.148 mm) axial depth of cut, and at a metal removal rate of 52.39 inch3/min (858.5 cm3/min). Cycle time on the upper chambers went from 34.5 hours to nine hours.
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By switching to the AE-TL-N, Ross Industries has reduced about 75 percent of cycle time on the upper chambers and is now on average achieving a 150 percent cycle time reduction on other aluminum parts.

“This end mill creates chips so fast that our machines chip conveyors couldn’t keep up,” said Ross Industries Machine Shop Manager Greg Williams. “We had to speed up the conveyors.”
Taken in consideration of factors such as tool change time, machine cost, labor, etc., it is estimated that an annual cost savings of $183,000 can be gained. In addition to the upper chamber part, Ross Industries has also converted all of its aluminum end mills to OSG’s AE-TL-N series in various sizes.

“With the performance and consistent tool life of the AE-TL-N we are able to run these tools lights out,” said Williams. “In some cases, it is able to achieve as much as four times the metal removal rate versus the competitor tool.”
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For more information on OSG’s AE-TL-N DLC coated end mill for non-ferrous materials and Ross Industries

by Peter Jacobs, via OSG USA blog

​There are almost as many distinct variations of CNC tools as there are finished products that could be milled. If you are familiar with the functions these tools perform, it will be much more straightforward for you to select the ones appropriate for the project you are working on.

​When it comes to the amount of time it takes and the quality of the work to be produced, choosing the appropriate cutting tool for your CNC milling machine, the material, and the type of milling can have a significant impact.

So here is a list of prominent milling tools utilized for CNC cutting.

Different types of CNC milling tools make it feasible to achieve the highest level of product customization. While cutting into and shaping different types of materials, several tools are employed.

The tool that should be utilized to cut also gets decided by the finalized design of the cut. Aside from these factors, specialists choose their tools based on how well they match the required speed with the desired finish.

​Depending on the ultimate purpose of the completed product, one of these two considerations might take precedence over the other.

The top 7 milling tools for CNC cutting are: 

There are numerous kinds of end mills, each of which is designed for a particular kind of cutting. All end mills cut at an angle of ninety degrees. 

A center-cutting end mill is what's required to make a vertical cut. These mills can cut both the center and the margins of the workpiece.

Non-center cutting end mills feature a hole in the middle of the tool and only contain cutting edges mostly along the ends of the mill. Since roughing end mills have fewer flutes than standard end mills, they are the tools of choice for making the initial cuts in a workpiece.

You will need finishing end mills with additional flutes to obtain a design similar to the part you want to produce. It will enable you to deliver a component that is cut with immense precision.

The tool employed on a project will vary depending on several factors, the most important of which is the number of flutes and the material of its composition.

​The production of end mills typically involves the use of cobalt, high-speed steel, and carbide as raw materials. More details about the different types of mills (as per their material) are given below.

• Cobalt: Cobalt mills only contain eight percent cobalt, with the remaining construction built of steel.  Cobalt mills can run at a pace that is 10 percent quicker than their counterparts.
• Carbide: The use of carbide end mills is recommended for finishing procedures.
• High-Speed Steel (HSS): It is the go-to material for mills of all kinds. It strikes an optimal balance between tool cost and service life. Since HSS has sufficient flexibility, it can be utilized for cutting iron and other materials.

End mills may perform a wide variety of cuts, the type of tool used depends on the type of cut being made:

• Face Milling - It is the process of just cutting into one surface of a material.

• Side Milling - It is used when chamfer mills are being employed to create beveled edges. To penetrate and smooth off the corner, you move the mill along the material's edge.

• Ramping - Ramping is a way of cutting at an angle into a surface, usually a diagonal cut through the material. It produces an angled toolpath while concurrently milling in the radial and axial directions. Toolpaths for ramping can be either circular or linear.

• Plunge Milling - It causes the end mill to plunge vertically into the workpiece. Like ramping, plunge milling necessitates using a center-cutting end mill to clean out the material from the hole's inside and perimeter.

• Slot Milling - Slot milling creates slots using an end mill to carve a groove in a material while cutting the edges on both sides simultaneously.

This tool is primarily used to create a level surface on a solid portion of the material. As the first step in milling, this is often performed on the top of the stock to smooth it out. The cutter inserts in a face mill's sole body can be changed for specialized cutting tasks. You would require more cutters to remove metal at a faster rate.

Drill bits resemble end mills in that they have a conical cutting tip on the end of a shaft with one or even more flutes. Twist drills are often made from solid carbide or High-Speed Steel (HSS). The drill's hardness, wear resistance, and lifespan can be improved by applying a gold-colored coating, such as TiN.

Fly cutters are considered the best to create a fantastic surface finish.  The clockwise motion of these cutting tools produces a mirror-like finish on the material.

These stocky tools first construct a precise conical hole to avoid the drill bit from drifting during a cutting operation and end up drilling the hole at an incorrect site. Screw clearance holes and counterbores can be drilled with the same tool thanks to multi-function drills that spot and countersink.

Reamers are mainly utilized to enlarge the existing holes in compliance with the tolerance while providing a superior surface finish. They help you ensure the accuracy of the roundness and diameter of a drilled hole.

​For reamers to work, a pilot hole of roughly the same diameter as the final product must first be bored.

Taps are tools used to cut threads into the interior of a material. Yet not every thread is produced by a cutting procedure. By applying pressure, Roll Form taps get inserted into holes, and the surrounding material is shaped to fit them.
​
Thread mills are similar but can be employed to cut internal or external threads.

The key to successfully machining products and components is selecting the appropriate CNC tool. Learn how each one functions, and keep in mind the use of the most beneficial ones in your manufacturing facility.

Peter Jacobs is the Senior Director of Marketing at CNC Masters. He is actively involved in manufacturing processes and regularly contributes his insights for various blogs in CNC machining, 3D printing, rapid tooling, injection molding, metal casting, and manufacturing in general.

In the aerospace industry, aluminium structural parts, such as wing parts and frame elements are generally milled from solid material. A buy-to-fly ratio of 22 (95 %) is not uncommon here.

New machine generations that have sufficient drive power and the necessary spindle speeds make the high-performance machining of aluminum parts cost effective. MAPAL has developed a new range of aluminium roughing mills especially for these machines.

The OptiMill-SPM (structural part machining) high performance mill is equipped with a cutting edge that makes up 60%-80% of its diameter. This represents the maximum contact depth for the high-performance milling of aluminum.

Thanks to a highly positive cutting edge geometry and optimised chip flutes, the cutting force of PCD mills is reduced by up to 15%. Even when milling on standard machines, this reduction in cutting force results in more efficient machining parameters, and hence in improved performance.

​The bottleneck form of the mill prevents the tool from bending during the machining process. Another advantage of this stable design 
is the clearance that is created between the wall of the part and the mill shank. This prevents chips from scratching the wall of the part, particularly if it has deep pockets.

OptiMill-SPM tools with internal cooling are available in a solid carbide design with a diameter range of 6 to 32 mm or in a PCD design with a diameter range of 6 to 50 mm as part of the standard range. The range of products also includes variants with the well-known CFS replaceable head system.

Alpha Granite & Tile in Austin, TX, has grown steadily since its opening in 2003, adding and diversifying machinery, materials and service offerings along the way, eventually earning the title “Accredited Natural Stone Company” from the Natural Stone Institute. They’ve expanded to deliver a range of custom residential and commercial stone surfaces, from wall cladding to kitchen countertops, in more than 150 colors of granite, marble, onyx, quartz, quartzite and ultra-compact sintered surfaces.

To keep up, Alpha Granite has invested in several advanced CNC machines, diminishing or altogether eliminating many of the laborious and time-consuming processes. Despite the technological advances, there was still a bottleneck that frustrated owners Denis and Sonia Phocas.

“Measuring tools in the stone industry was always a very laborious process,” explained Denis Phocas. “It’s archaic. You get wet, dirty and it takes a really long time. In reality, the process destroys tools because employees know the time and effort involved, so they tend to skip the necessary measuring intervals [ultimately cutting tool life roughly in half].

Dressing of the tools is also skipped, as this process needs to be done after a set amount of linear feet of work. In essence, the tools need to be measured and sharpened at set intervals to increase life.”

The traditional measuring process is manual. Measuring height and diameter to set up and inspect tools requires handheld instruments like calipers. Phocas explains how important accurate and sharp tools are to cutting stone profiles.

Since each profile requires several passes by six or seven different tools, each dependent on the accuracy, and more delicate than the one before. In other words, if the first tool isn’t dialed in right, the profile shape will be deformed, tools wear faster and the hours spent preparing them are wasted.

“Finding the center of one tool is hard enough,” he said. “Finding the center in relation to six others is very difficult.”

Phocas had heard about tool presetters, essentially a powerful microscope with a high-resolution monitor and basic computing power. It allows for precise inspection and measurement of tool edges. The process is relatively new to the stone industry and mostly limited to larger fabricators. As he explored further, Phocas began to understand why — only the big guys could afford them.

​The presetters he saw from his distributers were big, expensive and, frankly, had more bells and whistles than a family-owned independent shop like Alpha Granite would need. Phocas recalled thinking, “It was such a major expense. Who needs to spend $60,000 on something you don’t need fully automated? There had to be a smaller solution.”

Phocas approached suppliers about entry-level options, but they continued pushing more expensive options. He got creative and found a metalworking supplier, Big Kaiser Precision Tooling in Hoffman Estates, IL, that might be able to help. The Speroni STP Essentia they offered featured a compact bench-top design, could work with any brand of router tools and handle the more complex tool profiles in stone cutting with ease. Most importantly, it was much less expensive than the other options he had found.

After working closely with a representative from Big Kaiser, even trying out an Essentia in his shop, Phocas was convinced and decided to purchase one. While there are significantly fewer types of tools used for profile cutting, this new capability and process would be an adjustment at first, starting with installation.

“I had never worked with one of these,” said Phocas. “It’s a precision tool. I wouldn’t call it daunting, but the process was interesting. We installed it in the workshop manager’s office because we wanted to keep it in a clean environment and because it’s got a computer hooked up to it. In the end, the installation process was pretty straightforward.”

by, Bernard Martin

As carbide end mills gain higher and higher speeds and metal removal rates there has also been a trend by round tool manufacturers to tighten up the tolerances on both the cutting diameter and the shank diameter to improve concentricity. At the same time, shrink fit holders have become more and more popular because they hold a tighter concentricity as well.  To achieve this both the shank and the bore now have similar surface finishes and this has led to a problem  The tools pull out in the cut.

Shrink fit holders are the most accurate for TIR as the toolholder engages completely around round shank tools with a bore tolerance of -0.0001" to  -0.0003".  As high performance end mills have tightened shank tolerances to the same range of -0.0001" to  -0.0003" they have used finer and finer grain grinding wheels which give the shanks a 'shiny' appearance. 

Shiny means that the superfinished shank has a lower coefficient of friction. So, although the TIR is tighter, the shank is more "slippery".   End mills traditionally had surface finish of about 8 μin on the tool shank. But that's changed.  It's been recommended that tool shanks used in shrink fit holders should not have a finish finer than 16 μin. for optimum holding power, but tell that to the guy who just superfinished the end mill to a super cocncentric tolerance that you don't want it looking that good.

Everyone knows that the last thing you want is for the end mill to slip in the middle of a heavy cut or on the finishing pass of a high tolerance part.  These 'hi performance' end mills, often times have higher helix angles which are great for ejecting chips but also create a higher pull out force on that slippery shank. And reducing the helix angle is not the answer.

We  already know that the gripping pressure is a function of the interference between the tool shank  and the shrink fit toolholder bore. Most shrink fit holders have a already bore surface finish of between 12 μin. and 16 μin.  So they are ground to a very high tolerance and have about the same surface finish as the toolholder shank.

End mill manufacturers and machinist have tried a variety of methods over the years to stop the tools from pulling out. This has ranged from grit blasting the shank to rubbing chalk on the shank, but most everyone in the industry has felt that the problem really needs to be addressed by the longer life toolholder rather than the replaceable cutting tool.

That's the problem that Techniks wanted to address. Techniks claims that their "proprietary non-slip TTG594 compound virtually fuses the tool shank with the shrink fit toolholder."

ShrinkLOCKED Toolholders eliminate cutting tool pull-out and provide 4X the friction drive force compared to un-treated shrink holders.

It’s not just a rougher bore finish that enhances the holding power. TTG-594 is a compound that has a much higher Brinell hardness than carbide so it can “bite” into the tool shank. But this does not affect the ability to perform tool changes.

Techniks arrived at their 4x the holding power comes from torsion testing vs. a standard shrink fit toolholder. They used a ¾” carbide gage pin in a standard holder and found the torque at which the tool will spin in the bore.

They then tested the ShrinkLOCKED holder using the same test.

According to Greg Webb, at Techniks,
"We actually could not find the point at which the tool would spin in the ShrinkLOCKED holder as we broke the carbide gage pins at 4x+ times the torque of the standard holder. The holding power is greater, we just have not found a way to measure this, so we kept our claims conservative at 4x."