In-process tool checking saves time, guarantees quality

EDITOR'S NOTE: Case study courtesy Zoller Inc. For a related video sidebar about Zoller's >>caz<< software (Computer-Aided Zoller), click here.

Northern Tool, a division of Star Cutter Company, Farmington Hills, MI, is well-known for designing and producing special carbide cutting tools, often for automotive powertrain production, that accomplish more than one cutting operation in a single pass.

With its CNC tool grinders, OD grinders, roughing OD grinders and edge prep machines, plus blank prep machines and a cutoff and laser-etching machine, the company produces carbide drills, reamers, end mills, form tools – all are specialized to create a certain chip in a certain part. The potential cost in time, material and customer production of tools that do not perform optimally is significant.

With an investment in Zoller in-process tool measurement devices, Northern Tool is able to achieve up to 90 percent savings in the time it takes to inspect the complex tools it makes compared to the previous optical comparator inspection, assuring a correct grinding process before production fully ramps up.  With ZOLLER in-process inspection, the toolmaker can also guarantee the tools are ground as-designed—and can even detect if a tool may not operate as intended.

Matt Brothers, Production Supervisor, Northern Tool is tasked with tool inspection for the busy shop. He started in the industry in 2001 after schooling in electrical engineering. “Because I showed interest in tool inspection, I was put in the inspection department,” Matt said. “Tool inspection is what I do.”

“I am always looking for the latest and greatest thing out there to help the shop use the best technology available,” Matt said. “In 2006 I was introduced to Zoller through its »genius 3« tool inspection system. I was trained on that and saw how easy the Zoller tool inspection software is to use and have been convinced ever since.”

Northern Tool recently installed a ZOLLER »pomBasic« universal tool inspection machine for process-oriented measurement and inspection of drills, milling cutters and countersinks. »pomBasic« eliminates the need for the optical comparator and provides much greater precision—and more usable data. A compact bench top device, »pomBasic« uses incident light for checking tool geometry and tolerances. It is installed on the shop-floor--right next to the tool grinding machines.

“»pomBasic« integrates the function of both CNC inspection machine and optical comparator in one platform and allows us to save and print data,” Matt said. “We can also use it to determine why a tool may not be performing well enough. We recently created a measurement inspection program for a drill point that was not performing well enough in the field. The data we collected pointed to small ways we could improve tool geometry to get the desired cutting results.”

Simple to use, all the grinding machine operators verify their initial production on »pomBasic«. The operator simply inserts the tool in a fixture, positions the tool according to directions on the device screen, initiates measurement, and quickly completes the collection of valuable tool data. »pomBasic« includes automatic cutting edge detection for high accuracy, wizard-guided measuring processes, and test logs at the push of a button. “We use our »pomBasic« for first piece and benchmarking, taking pictures, and documenting first piece inspections of step lands, radii, angles, and other 3D features,” Matt said.

“Previously we had numeric data only, now we have a clear complete image as well,” Matt said. “Having this capability for first-piece inspection is essential for us. We can also see the surface finish on the tool. Because the device tells the user where to align the tool point for inspection, everyone is checking the same feature the same way every time, taking the human error out of the situation,” Matt pointed out.

For process-oriented measurement of edge radii on cutting tools, the bench-top, carbon fiber »pomSkpGo«  assures high precision due to its stiffness. It is simple to use, and it’s busy all day. “We use Zoller »pomSkpGo«  for all edge preparation inspection, checking k-lands and radii,” Matt said.

Edge preparation is a big part of tool inspection at Northern tool. With the ability of CNC metal cutting machines to run continuously and untended, cutting tool performance demands are increasing. The need to produce more predictably performing tools is essential. Although microscopic, tool edge defects can lead to erratic tool performance or tool failure, so eliminating these defects helps optimize tool performance. Tool edge preparation can strengthen the tool cutting edge, lengthen usable tool life, reduce the likelihood of the edge to chip, improve part quality and consistency, and enhance work piece surface finish.

Northern Tool  precisely grinds a chamfer—K-land-- along the cutting edge of its carbide cutting tools that reduces the  stress concentration on the tool edge during machining, thereby preventing edge chipping and increasing tool life. The K-land is vital to the quality and performance of the Northern Tools product. On the day of the visit, a drill/back chamfering combination cutter was on the Zoller.

“»pomSkpGo«  on the shop floor lets us check a K-land fairly quickly,” Matt said. “With a our touch probe it would take about 5 minutes. On »pomSkpGo«   it is a 30-sec. inspection and it is more repeatable while providing more information. Alignment is fussier on the probe-based checker because the probe tip has to be normal to each feature being measured, but the noncontact inspection on  »pomSkpGo«   is based on depth and it takes alignment issue out of the equation—very important when the tolerance on a K-land is .0005”,” Matt said.

“»pomSkpGo«  has been a big time saver for measuring K-lands. We save the tool data under the ID number, orient the tool in the fixture, and capture images. The inspection data we get is extremely helpful. We get a trace of the edge preparation and a live image, actual radii over 100 cross-sections, and we can print out final inspection data. Previously, we had some data; now we have more fine data plus multiple images and it is definitely helping us achieve the quality we need as a tool manufacturer.” 

“The shop standard is to inspect the first-piece and then 10% of the whole lot pre-and post-coating. Sometimes we check each one, depending on the tolerance. The impact of the tools not being perfect is enormous. That’s why the investment in the Zollers. We want to be able to check the tools better than the customers can. Most of our customers accept the Zoller report as confirmation the tool is right.

“The POM machines are key to our in-process inspection and data collection. All the data collected with the Zollers is scanned and saved in inspection reports by lot number which is then shared with the customer certifying the tool. With this information we can go back and see what made the tool run well or with difficulty, feature by feature.”