… because there’s now a better way of grinding punches …
CNC tool grinders have a long history of swallowing an ever increasing range of grinding jobs apart from just drills and mills. Broaches, reamers, inserts, burrs and medical tools are now routinely produced on tool grinders. Medical implants, turbine blades and pinion gears are also fast succumbing to the superior versatility, accuracy and speed of grinding on modern 5 axis tool grinders.
We think that turret and pill punches and some inserts will be the next to fall totally under the domain of the CNC tool grinder. In fact, so confident are we of this prediction that last year, we discontinued the very successful ANCA PGX; a dedicated, large wheel, 3 axis production punch grinder with a heritage going back nearly 20 years to our earliest entry into the punch grinding market, the CL4, installed at Elizabeth Carbide in the UK for grinding pill punches. Some people have asked why we no longer make the PGX. The answer is simple. Our tool grinders are better at grinding punches than a punch grinder! When we say this, some people are understandably skeptical, so here are the facts of why we believe that using an ANCA tool grinder is a much better solution for grinding punches than using a dedicated punch grinder;
Fact 1: You don’t need huge wheels to grind punches
Conventional wisdom says that to grind HSS punches, the best set-up is a large machine with a Silicon Carbide or Aluminum Oxide wheel in the 24 to 30” (600-760mm) range to handle the large metal removal rates required during roughing and to provide enough wheel stock to get you through a sizeable number of parts. But this just isn’t true anymore as super-abrasive wheels have come a long way in recent years. A 30” CBN wheels would be prohibitively expensive but by using a dress-able CBN wheel of a much smaller diameter on a CNC tool grinder, you can actually grind punches faster and your wheels will last just as long, if not longer than a large standard abrasive wheel on a punch grinder.
Says Tom Groulx, application specialist at ANCA Inc.,
“When we first introduced the punch grinding application on the TX7+, we had some very demanding and skeptical customers who already had ANCA PGX’s and other dedicated punch grinding machines in their shops. We spent several months fine tuning the process and are now able to consistently produce as good or higher metal removal rates using 8” (200mm) CBN wheels over what we were able to achieve using large Aluminum Oxide wheels on the PGX. The other thing we noticed is that the traverse time around sharp corners is much less with smaller wheels because the arc radius is so much smaller. This all combines to give us faster cycle times on the TX7+ than was possible with dedicated punch grinders, including ANCA’s PGX!”
And with an integrated wheel exchanger such as on the ANCA TX7+ you can use different wheels for roughing and finishing within the same cycle, saving you even more time and money.
Fact 2: Tool grinders can meet your most challenging tolerances
Tool grinders have become more rigid and accurate over recent years. Everyone is under pressure to produce to tighter tolerances. This is certainly the case in the tool making industry. Tool grinders have evolved to meet this challenge head on and now regularly operate to better than 5 microns. This is now directly applicable to punch tools where profile accuracy is extremely important and even with the high stock removal rates of punch grinding, ANCA’s tool grinders are more than capable of meeting the demanding accuracy requirements of the punch tool and insert market. Anthony Basset is the president of Rigibore Inc. in Mukwonago, Wisconsin, USA. He sums up his experience nicely,
“We are grinding consistently to within 1 to 2 microns with our versatile ANCA … and the ANCA iPunch software”.
Accuracy is further enhanced by using the smaller super abrasive wheels that are so well suited to the TX7+ as they are easier to dress accurately and hold their balance better than large porous Aluminum Oxide wheels. Andrew Whitworth, Director of AW Precision Ltd. in Rugby, UK says,
“‘Due to the wheel having a smaller surface area to dress I am having no issues at all with size loss over a large batch. We use the TX7+ to grind punches from 3mm (0.1”) up to 32mm (1.25”) ‘.
Fact 3: 5 axes makes it easy to cover the range of punches you will encounter
Whilst many punch forms can be ground with 3 axes, you will encounter punches which are not completely convex in profile, but have one or more concave features. These punches, commonly called keyhole punches, cannot be ground on a conventional dedicated punch grinder. Instead, if the radius of the concave curve is smaller than your wheel radius, you need to swing the wheel around 90 degrees and attack these punches end on. A 5 axis tool grinder is already optimised for end on grinding so it’s a simple matter for a modern CNC tool grinder to swing the spindle saddle around to grind keyhole punches. Furthermore, the rotary dresser on your ANCA tool grinder, combined with easy to use software will allow you to quickly dress any keyhole punch form you need onto your grinding wheel.
Add to this, the ability of ANCA CNC tool grinders to easily pivot about the contact point during punch grinding and back tapers become easy to setup and grind as well. “I have had quite a bit of 'fun' playing with positive and negative tapers on punches (using the TX7+). On the PGX it was a pain achieving negative tapers”, says Whitworth.
Now, if this level of flexibility is not enough, then how about adding the capability to perform other operations that were traditionally done as additional processes on other machines? The ANCA TX7+ can perform operations on the end face of the punch, such as rooftop and other shear profiling which reduce a punch’s tonnage requirements. With a TX7+ fitted with a wheel exchanger, you can also, automatically swap out the grinding wheel for a rotary drill and then drill the ejector pin mounting hole directly into the end face of the just ground punch tool. All in a single set-up, now that’s versatility for you. Try doing that with a dedicated punch grinder.
Fact 4: You’ll make more money from a tool grinder
The best thing about installing an ANCA tool grinder to grind punch tools is that you have incredible flexibility to utilise the machine for other tool grinding tasks. If your orders for punch tools slow down, just reschedule the machine to make or sharpen standard tools, or perhaps try your hand at the rapidly emerging market of medical tool and implant grinding. Your ANCA tool grinder is more than capable of all of these jobs.
The secret is ANCA’s renowned software. Known the world over as the most flexible tool grinding and simulation software around, the combination of ANCA’s complete software package for punch grinding (iPunch) and 3D simulation (CIMulator3D) mated to an ANCA TX7+ will have you fully capable of high quality punch tool manufacture in no time at all.
To sum up, recent advances in super-abrasive wheels and the increasing accuracy and rigidity of tool grinders combined with the power and flexibility of advanced 5 axis control systems and application software for punch grinding mean that you can now be more competitive in the punch grinding market with the ANCA TX7+ tool grinder and iPunch software, than you can be with a dedicated punch grinding machine. This is why we stopped making our very successful dedicated punch grinder and why you should consider an ANCA TX7+ for your punch grinding needs.
But don’t just take our word for it. Give ANCA a call today and take a TX7+ for a test drive on your punch catalog and see how well an ANCA tool grinder can perform against the “big wheels”!
Click here for more details on the ANCA TX7+
First published in The Sharp E Newsletter, July, 2010
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