Over the years, many of our customers have come to us because they were regularly breaking taps.

This meant that the holes had to go from a depth of .150" to .190". The 2-56UN thread’s major diameter was .086", and the drill diameter .070".

Repeatability was nearly impossible on his CNC equipment, and he literally came in every Saturday to tap the holes by hand. When he started talking with us, he was breaking his taps after only 20 holes — an extraordinarily short tool life.

By re-examining his technology, and switching to Carmex Precision thread milling, he was able to accomplish the threading of 683 holes with a single thread-mill on his CNC equipment.

Despite the number of passes, the wear factor between the first and the last holes could only be measured in tenths, and the customer was able to get the thread detail back to its original .150" full thread depth. Perhaps just as important, his Saturdays are now “tap-free.”

PMC-Colinet has a long history in the pipe and tube market, having started in 1912 and introduced the world’s first carbide-tooled pipe threading machine in 1958.  Today, the company is established as a primary supplier of machines to the OCTG sector.   Its customers include integrated steel mills that sell finished pipe and couplings to the oil and gas industries, specifically using the company’s machines for threading products for downhole drilling applications.  PMC-Colinet also supplies cutting tools, consumable tooling, aftermarket parts and field service to the industry.

Recently, PMC-Colinet did an assessment on one very challenging job, namely, cutting keyways into large sections on a high-precision cutting tool head made of Nitralloy.  For many years, the production had involved the use of a shaper to produce the keyway in the bore of the die head.  Typically, the bore ranged from 6” to 13” in diameter and more than 12’ in length.  These keyways have extremely tight tolerances, with location at +/- 0.0005”, width at +/- 0.001” and depth to +/- 0.0025”.

One style of cut is a 3-step keyway that does not run all the way through the bore, stopping at a window that is milled from the outside diameter.  This situation prevented the PMC machining department from using a ram EDM to produce the keyway.  The only options previously used were to rough the keyway on an old shaping machine, then send it out for ram EDM.  This process required 50 hours on the shaper, plus approximately a week for the ram EDM.  Another option was to do the job entirely on the shaping machine.  Roughing the keyway had to be much more precise and usually required about 61 hours.  Plus, an additional 145 hours were required to finish the part, normally.  These times included 10-12 hours for set-up.

The team at PMC, led by Milling Foreman Rick Kokish, decided to explore other methods to produce this part on its Monarch 175B VMC.  They conducted an exhaustive search on the Internet, turning up over 133,000 hits for 90º angle heads.  After more than 30 hours of gleaning out the unsuitable products, they narrowed the search to just two vendors.  Both manufacturers visited the facility and brought out their standard angle head designs.   One of the companies, Heimatec, quickly realized this job would require a custom 90º head design to satisfy all the requirements.

One competitor brought a standard 40 taper tool, while Heimatec presented a larger, heavier 50 taper unit.

A week later, Preben Hansen, Heimatec’s president, supplied a drawing for the proposed custom product.  PMC engineering reviewed both the standard and custom designs and awarded the project to Heimatec.

The angle head supplied was designed to perform a wide variety of cutting tasks on the various end products produced by PMC.  On the keyway in a bore 6” in diameter and 12” in length, using the Heimatec 90º head, PMC spent 6 hours in setup, 3 for roughing and 3 for finishing, plus 12 to 16 hours of actual cutting time.  This represented a total savings of 184 hours on a single part.  Though the head appeared too slender to remain rigid during the entire cutting cycle, according to PMC sources, the performance was deemed very successful.

Heimatec’s head design for this custom radial drilling and milling head features an adjustable tool stop, 3 support pins for stabilizing the tool, CAT 50 taper style, 360º indexable pivot on the angle head and inclined tooth gear design for maximum rigidity.

During the project, Preben Hansen from Heimatecc supervised the installation.  After the stop block attachment and grinding of the supports pins for the head were accomplished in just one day, the head was mounted and several experimental cuts were performed.  Hansen spent time with Rick Kokish as well as CNC programmer Barry Spence at PMC, discussing various options for programming the head on the Monarch VMC.  The very next morning, the setup was performed and an actual keyway was roughed.

Results ongoing have continued to satisfy all requirements, according to PMC sources.

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

PEEK polymer is available in two basic grades: industrial and medical: 

​"Industrial-grade PEEK is a strong thermoplastic that retains its mechanical properties even at elevated temperatures. The flame-retardant material is abrasion resistant, has high impact strength and a low coefficient of friction. Industrial-grade PEEK components are used in the aerospace, automotive, chemical, electronics, petroleum, and food and beverage industries.

Medical-grade PEEK possesses those same physical properties in addition to biocompatibility, high chemical resistance and compatibility with several different sterilization methods. It is also naturally radiotranslucent when viewed using X-ray, MRI or computer tomography (CT). ​Medical-grade PEEK provides doctors with an unobstructed view of tissue and bone growth around the PEEK implant during the healing process.  Some implantable-grade PEEK polymers have a bone-like stiffness and can remain in contact with blood or tissue indefinitely."

Because of the thermoplastic properties, too much heat at the cutting edge results in Built Up Edge (BUE) and tool pressure affects part tolerance.
​
That where NTK's KM1 grade insert work great. The inserts are extreｍely up-sharp edge and the mirror insert surface creates excellent surface finishes.

1. Limiting Heat Build-up – The softening or melting temperatures of engineering plastics are roughly 1/10th those of metals.
 
2. Melting or Scorching– The thermal conductivity of plastics is low relative to metals.  Most of the heat generated by machining will stay at the surface.  Temperatures at the surface can rinse unexpectedly high. 
 
3. Loss of Tolerance – If the overall temperature of the stock changes during or after machining, expansion or contraction can cause the part to fall out of tolerance.  Softening of the stock can allow it to deflect at the surface under the pressure of the cutting tool.  When the pressure is removed, the stock will recover and fall out of tolerance. This can frequently  be managed by using lubricants and changing tooling or speed.
 
4. Controlling Deflection – Plastics inherently vary in their stiffness (modulus) and are more elastic at higher temperatures.  The entire stock can deflect under the pressure of cutting.  Proper tooling and support remains important and particular attention should be given to adequately supporting the work.

NTK Cutting Tools USA launched its first Webinar on 30th January, 2018. The featured presenter is Steve Easterday, NTK's Swiss Product Manager.

The topic focuses on chips created during Swiss machining operations and the mainstream concept which is that breaking the chip is important. But is this accurate? NTK has a different concept of Chip Control.

The topics covered in the video below include:

• Chip Problems Swiss Machining.
• The NTK Concepts regarding chip breaking.

There are a few different ways to break a chip. Many people tend to think that the best methods of breaking chips in swiss machines are through the use of chip breakers on the inserts, slowing down the speed, increasing the feed, taking a bigger depth of cut and through the use of high pressure coolant.  Each one of these, or some combination of them is certainly what is commonly used to gain chip control.

NTK creates a "softer" chip because there is much less heat transferred to the workpiece AND the chips. The translates into better part quality, longer tool life and much more stable machining.

​Check out the video below for all the details on chip breakers and their toolholder solutions.

Author Kip Hanson, Contributing Editor, Cutting Tool Engineering
(520) 548-7328
khanson@jwr.com
Kip Hanson is a contributing editor for Cutting Tool Engineering magazine. Originally Published: September 12, 2017 - 3:00pm

Shopping for a machining center was simpler when buyers had only two basic spindle choices: CAT or BT. Both of these “steep tapers” have an angle of 3.5 in./ft., or 7" in 24" (7/24), and are based on the 1927 patent by Kearney & Trecker Corp., Brown & Sharpe Manufacturing Co. and Cincinnati Milling Machine Co. 
​
With the development of automatic toolchangers in the late 1960s, machine tool builders in Japan modified the patented design and invented the BT standard. In the 1970s, tractor manufacturer Caterpillar Inc., Peoria, Ill., changed things again with a flange design now known as CAT, or V-flange.

During the late ’80s, machine tool builders began offering vertical and horizontal CNC mills with spindle speeds higher than the 6,000 to 8,000 rpm common at the time. As rpm increased, so did problems with steep-taper toolholders.

​Chief among them is the tendency for the mating spindle and toolholder tapers to stick together. This is caused by the expansion of the spindle housing at high speeds, which allows the toolholder to be pulled upward into the spindle taper, jamming it in place.

HSK spindles, like the one shown in the illustration below, offer advantages steep-taper styles can't.  

​One way to eliminate this problem is by extending the toolholder flange upward, thus creating a hard stop against the spindle face and preventing further Z-axis movement. ​

This is the approach taken by BIG KAISER Precision Tooling Inc., Hoffman Estates, Ill. Jack Burley, vice president of sales and engineering, said the BIG-PLUS system—developed in 1992 by BIG Daishowa Seiki Co. Ltd., Osaka, Japan—relies on a bit of elastic deformation in the spindle to provide dual points of toolholder contact at its face and taper, eliminating upward holder movement as the spindle expands.

He said it’s also more rigid, with tests showing that the deflection on a CV40 BIG-PLUS toolholder measured at 70mm (2.755") from the spindle face is only 60µm (0.002") when subjected to 500kg (1,102 lbs.) of radial force, roughly half that of a traditional V-flange toolholder.

Burley does not recommend BIG-PLUS for older machines that have never seen these toolholders, because CAT and BT taper-only contact holders tend to bellmouth the spindle over time, leading to undesirable results.

BIG-PLUS, like any dual-contact toolholder, requires particular attention to cleanliness, as chips caught between the spindle face and the toolholder can cause serious problems.

​He also recommends staying below 30,000 rpm when using 40-taper holders, noting that higher speeds are better handled by HSK spindles and holders.

Bill Popoli, president of IBAG North America, North Haven, Conn., said the company started building steep-taper spindles in the late ’80s, but 95 percent of its work has since transitioned to HSK spindles. As mentioned earlier, the extreme accuracy needed to guarantee near-simultaneous contact between the spindle face and taper is challenging, requiring micron-level tolerances in toolholder and spindle alike.
​
These requirements were impossible to meet when steep taper was first developed, Popoli said, resulting in looser standards overall for CAT and BT spindles than the ones applied to HSK spindles and toolholders. Because of this, purchasing an HSK or equivalent toolholder automatically makes one “part of the club” when it comes to balance, accuracy, repeatability and tool life.

That’s not to say, however, that shops firmly married to steep tapers should settle for less. Popoli recommends purchasing the highest-quality tooling possible and paying close attention to the stated tolerance.

Always stay below 20,000 rpm with 40-taper holders, and reach no more than 30,000 rpm with 30-taper ones. Use balanced holders and high-quality retention knobs that have been properly torqued—otherwise distortion at the small end of the taper may occur. And whatever the taper type, keep the spindle and toolholder clean at all times.

Bob Freitag agreed. The manager of application engineering at Minneapolis-based metalworking products and services provider Productivity Inc. said the lines are evenly split between traditional 40- and 50-taper CAT or BT tooling (much of which is BIG-PLUS) and HSK. 

“It really depends on the application,” Freitag said. “Most of our die and mold machines in the 20,000- to 30,000-rpm range will have an HSK63A or HSK63F. When you get up around 45,000 rpm, you’re probably looking at an HSK32. But in horizontal machining centers and lower-rpm, high-torque verticals, you’ll see mostly steep tapers, as this is generally preferred for deep depths of cut and lower feed rates, where you’re removing a lot of material at once.”

For shops that want to make the leap to an HSK machine but are leery of investing in new toolholders, Freitag advised:

​“Anytime you buy a new machine, you should buy new toolholders to go with it. If not, the imperfections of the old toolholders will soon transfer themselves to the spindle on the new machine.”

Clamp confirmation for any system, UNILOCK or otherwise, is a sound design criterion when building any workholding system.

​It is very common to see clamp/un-clamp confirmation in many automated loading systems as safety interlocking of the CNC machine, robot, robot EOA (end-of-arm) tooling, and workholding can all be integrated to a single master control.

Un-clamp confirmation does have a place in manual situations as well, mostly in large part processing, where cranes are used to lift parts off.

When a clamping system is not directly visible underneath a large part, then this requires an external indicator confirming that the system has successfully un-clamped and that it is safe to lift.

The indicators and sensors can be pneumatic switches which are offered by BIG KAISER or electrical proximity switches as offered by many other companies.

Precision Cutting Tools already holds one of the highest tolerances on shank diameter in the industry for their end mills.  All PCT End Mills Shanks hold an h6 tolerance! That means that 
1/8" - 1/4": -0.0001"/-0.0003"
1/4" - 1/2": -0.0001"/-0.0003"
1/2' - 1": -0.0001"/-0.0004"

A tighter grind tolerance often times will mean a much shinier polished shank.  A polished shank is more apt to have lower coefficient of friction which makes it more prone to slip particularly while being held in a collet type toolholder.