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.

OSG Corporation has announced the release of the ADO-MICRO small diameter coolant-through carbide drill series for stable and high efficiency drilling in small diameter deep-hole applications.

Poor chip evacuation is a common complication in small diameter deep-hole drilling. Micro sludges can be easily accumulated around the outer periphery of the cutting tool, which is a key cause of abrupt tool breakage.

The ADO-MICRO features a unique double margin geometry with an extended flute and shortened end margin to enhance chip evacuation capability.

In addition to the outstanding chip ejection performance, the double margin configuration supports the straightness stability of the tool and reduces rifle marks on the inner surface of holes.

Furthermore, the ADO-MICRO features a pair of large oil holes and employs a hollow shank design to allow large coolant flow volume for trouble-free chip evacuation.

The ADO-MICRO is coated with OSG’s original IchAda coating that provides excellent surface smoothness in conjunction with high abrasion resistance and heat resistance to enable small diameter tools to achieve long tool life.

​With the ADO-MICRO’s unique tool geometry and IchAda coating, non-step drilling is made possible even for deep-hole applications, enabling high processing efficiency.

The ADO-MICRO is suitable for carbon steel, alloy steel, stainless steel, cast iron, ductile cast iron, aluminum alloy, titanium alloy and heat resistant alloy. The ADO-MICRO is available from diameter 0.7 mm up to 2 mm for drill lengths 2xD and 5xD, and diameter 1 mm to 2 mm for drill lengths 12xD, 20xD and 30xD.

Got an application you want to try this on? Give us a call! 

We've assembled a few tips on drilling that you may want to pass along to your team.

During drilling operations, chip formation is very important to keep an eye on. If you are getting long unbroken chip with jagged edges, your feed rate is too high. If you are getting tight spirals but the chips are not breaking apart, your feed rate is too low.

The Ideal chip shape is small tight curls, Like little "6's and 9's". When you are getting these shapes of chips then you will get best tools life and finish on your part.

If your drill is getting chipped only on one edge or if your drill has more wear on one cutting edge than the other, the cause could be bad run out of the drill or bad alignment of the machine.

This means one side of the drill is experiencing more axial forces than the other. If you correct the run out of the drill and alignment of machine spindle, the problem will be solved.

If your drill has too much run out, you will have issues such as hole expansion, bad hole perpendicularity, and poor surface finish.
Drill run out should be less than 0.0008"(0.02mm) when setting up. The run out increases with the speed, thus, when drilling a deep hole.

OSG recommends making the pilot hole 0~0.003"(0.08mm) oversize and inserting a long drill at 0~500rpm so that the drill is fitting properly in the pilot hole .

The V-Series HELIOS® drill is the 1st drill to process deep holes 10X-20X diameter, without pecking and without the use of internal coolant supply.

Flute form, point thinning and compound lead construction are all patented technologies developed by OSG to make this drill do what no other parabolic HSS-Co drill can.

The addition of our exclusive WXL coating technology makes non-peck drilling repeatable, even in the longest of production runs.

Last but not least, don't forget that now through August 31st, save 12% on select A-Drills!l

...and below is the segment from "How It's Made" that covers the more general principles of making a HSS end mill.  

​You can see that OSG has a very advanced process for making their carbide end mills.

OSG's Aerospace training for composites & high temp alloys covers:

​Difficulties when machining, troubleshooting, the best tools for aerospace machining and more! 

What You’ll Learn

• Composite and High Temp Alloys Overview
• Difficulties Machining Composites & High Temp Alloy
• Troubleshooting Manufacturing Issues
• Best Tools for Machining Composites & High Temp Alloys
• And More!

Who Should Attend:
This seminar will benefit anyone curently machining or interested in learning more about machining composites and high temp alloy materials. 

Machinists, operators, manufacturing engineers, programmers, etc.

Seminar Agenda
9:00 - 12:00 - Composites

• Introduction to Composite Materials 
  • What are Composites?
  • Types of Composites
  • Advantages and Disadvantages
  • Thermosets vs. Thermoplastics
• Difficulties Machining Composites 
  • Delamination, Uncut Fibers, Etc.
  • Troubleshooting
• Tools for Threading, Drilling and Trimming Composites 
  • Breakdown of Tools and Case Studies

12:00 - 1:00 - Lunch (Provided)
1:00 - 4:00 - High Temp Alloys

• Overview of High Temp Alloys 
  • Super Alloys
  • Titanium
  • Stainless Steels
• Difficulties When Machining 
  • Troubleshooting
• Tools for Machining 
  • Chip Breakers

by David Aly, Aerospace Specialist, OSG Tap & Die
 
Just because you’ve tried one forming tap, doesn’t mean you’ve tried them all. We had the recent opportunity to prove that OSG forming taps are better than the rest. 
 
As a supplier of custom fabricated metal products and machinery, one of our customers approached us wanting to get better chip control during their tapping operation. Located in Winona, Mississippi, they have a 92,500 square foot manufacturing facility for producing fuel tanks, hydraulic tanks and custom designed machining fixtures.

​After discussing the customer’s chip control needs, I recommended OSG’s EXOTAP® NRT® Forming Tap, a more stable, thread rolling tap that makes threads by compressing the work material without creating chips. Because no chip is produced, breakage due to chip packing and bird nesting is eliminated.

The EXOTAP® NRT®  also has significantly reduced friction resistance because of its special threading design and surface treatment. Made from VC-10 Powdered Metal High Speed Steel, this forming tap has a longer tool life when tapping difficult to machine materials like carbon steels, alloy steels, stainless steels and aluminum alloy.

​Initially, the shop foreman, Mr. William Smith, was hesitant about using a forming tap due to a bad experience with a competitor’s brand. After I showed William a presentation and a chip flow demonstration video, he was willing to give our forming tap a chance.
 
We approached his staff with OSG’s EXOTAP® NRT® Forming Tap in hand.  After explaining the test with the operator and reiterating
that there will be no chips, we began the trial.

Next Generation Tooling is excited to offer some new services coming in 2015!

Below is a very fast video of our new training series on Tapping which we can present to your manufacturing team at your site. 

It's a comprehensive overview of screw thread terminology, thread forms, fundamentals of threads, classes of fit, Tap basics, types of chamfers, the tapping process,tap types, screw thread inserts, helix angles, core diameters, re an hook angles, thread reliefs, pitch tolerances, H limits, Tap substrates, Surface treatment and coatings, tapping speeds, tap drill sizes.

written by, Dave Nelson,  edited by Bernard Martin

Understanding tool geometry and selecting the right tap for different workpiece materials can help take the anxiety out of tapping operations. Many machinists have learned to dread tapping.

The story goes something like this. They press cycle start and then step back because the machine is now in control. If the tap should hit bottom, too bad; the cycle must be completed—no feed-hold allowed here.

​If the wrong feed rate was programmed, tough luck; the feed rate override is disabled. What else is there to do but cringe as the tap enters the hole?

That’s one of the reasons tapping causes anxiety among CNC machine operators. That anxiety leads operators to take too many precautions to assure the tap will complete its job of cutting an internal thread.

Other factors can fuel tapping anxiety. Feed rates are typically much higher than for most other cutting tools.

​With each revolution of the tap, the tool needs to advance one thread pitch. 

However, while tapping can be tricky, it is not beyond understanding. Tapping problems can be simplified and reduced by understanding tool geometry and what taps are best suited for a given application.

Lowering the chip load can eliminate premature wear on a tap. 

​Defined as the load induced on any one cutting edge, chip load is typically controlled by altering the feed rate. As mentioned earlier, this is not possible when tapping but the chip load can be altered through tap selection.

One approach might be to use taps with more flutes. With every flute added to the tap, a cutting face is added. With more cutting faces, the load on each tooth is reduced. For example, a 4-flute tap would have half the chip load per tooth of a 2-flute tap. This jives with standard metalcutting advice, which is to always use a maximum number of flutes. However, for tapping this advice would probably be wrong.

“More flutes means there is less space for chips as they are cut,” said David Miskinis, senior application specialist, holemaking for Kennametal Inc., Latrobe, Pa. “More flutes on the same circumference means smaller flutes, both in width and depth. With smaller space comes the risk of packing chips, which can lead to broken taps.”

​“Basically, a longer chamfer length means longer tool life,” said Dr. Peter Haenle, president of Guhring Inc., Brookfield, Wis. “The load during the cutting process is distributed over a longer cutting edge with a lower chip load.”

There are three common lengths of tap chamfers: taper at 7-10 threads, plug at three to five threads and bottoming with one to two threads. To provide more options, tap manufacturers have added a few more forms, including a form consisting of a two- to three-thread length, sometimes called semibottoming.

Adding length to the chamfer distributes the chip load over a longer cutting face. Effectively, more teeth are cutting the thread, similar to a single-point threading tool taking multiple passes.

“Chamfer lengths have a huge impact on tap life because they affect chip load,” Miskinis explained. “When comparing chamfer lengths of four threads or fewer, the tool life will double for every half thread added to the length.”
Clearly, increasing chamfer length in taps is desirable. Shorter chamfer lengths, such as in bottoming taps, wear faster and should be avoided, if possible. Unfortunately, there may not always be a choice.

“Taps with smaller chamfer lengths are usually used to keep the difference between hole depth and thread length to a minimum,” Haenle said. “Very often, the design of the part forces the use of taps with short chamfer lengths.”

​Another way to tap more effectively is to manage chip thickness. For example, it is possible to thin the chip too much when tapping. Stringy chips can result from using taper chamfers and the tap may create a bird’s nest of chips, preventing lubricant from reaching the tool and chips from properly evacuating. As in other types of machining operations, increasing chip load can help break the chips.

Tap breakage is another issue that creates anxiety among machinists. The saying goes that it’s not the fall that kills you, it’s the sudden stop. But in tapping, it’s not the sudden reversal that causes taps to break, it’s the chips clogging the tool flutes. In some cases, this means chips are packed so tightly so that newly formed chips simply have no place to go, and the tap breaks from the stress.

Because tapping is a relatively complex operation, and because there are so many taps to choose from, selecting a tap can seem a daunting task. The main reason there are so many taps is because there are so many work materials. Tap manufacturers tailor tap design to the work material primarily through rake and relief.
​
The cutting face is that portion of the tap flute located between the major and minor diameter of the thread that cuts, or shears, the workpiece. The rake is the angle of the cutting face compared to a line from the center of the tap to the cutting face at the major diameter.

A rake is positive if the crest of the cutting edge is angularly ahead of the remaining part of the face. While not as strong as negative rakes, positive rake angles have excellent shearing capabilities.

A negative rake has the crest of the cutting face behind the rest of the cutting face. While this is a stronger geometry than a positive rake, it also requires more torque and creates more heat in the cut.

The shape of the cutting face is also a factor in tap performance. Cutting faces can also be straight or curved. The straight surfaces are normally referred to as rakes or straight rakes and the curved surfaces as hooks.

“Applying a rake, or straight face, will improve strength while a hook, or curved shape, will result in greater shearing ability,” said Andrew Strauchen, engineering and marketing manager, OSG Tap & Die Inc., Glendale Heights, Ill. “For performance taps, cutting [rake] angles are determined by the intended work material; higher angles are used for softer materials and low angles for harder materials.”

Tap relief is defined as the removal of metal from behind the cutting edge. A higher relief indicates more clearance between the tool and the workpiece. There are three main types of relief: concentric, eccentric and con-eccentric.

Concentric relief indicates that the lands of the tap, the part of the tap that remains after the flutes are cut, are concentric with the threads. This actually provides no relief and thus the surface of the tap rubs on the surface of the threads being cut.

Hand taps are made with concentric relief. Because they are used by hand, cutting speeds are low and friction and heat do not limit tool life. Because the lands are concentric, the threads on the tap help guide the tool into the threads on the workpiece as they are cut.

Eccentric relief means that the lands are cut to an arc that is not on center with the bulk of the tool. This type of relief provides the best clearance between the tap and the thread being cut. Because the tool doesn’t rub against the material, friction can be minimized.

Con-eccentric relief is a combination of the other two styles. A small part of the land remains concentric at the leading edge while the rest of the relief is eccentric. This style provides a balance between reduced friction, as provided by eccentric relief, and tool guidance, as provided by concentric relief.

Concentric relief and, to a lesser degree, con-eccentric relief taps rub the workpiece material as the tool enters and exits the hole, causing friction, which in turn produces heat. Heat diminishes tool life. As a result, premium taps are most often made with eccentric relief.

​“The higher the relief, the lower the friction of the tool,” Haenle said. “Therefore, a higher relief results in less wear and longer tool life. However, a lower relief guides the tool better in the axial direction because it has less tendency to cut in the radial direction.”

Premium taps are not for all machines. A high-end tap will not guide itself when creating the thread. Therefore, taps with eccentric relief require the machine’s feeding mechanism to be highly accurate.

“In newer CNC machines, you can use taps with higher relief angles,” Haenle said. “On the other hand, when using older equipment or drilling machines with less rigidity and with standard tapping chucks, a smaller relief angle helps to guide the tap better.”