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.”
Related Glossary Terms
Machining a bevel on a workpiece or tool; improves a tool’s entrance into the cut.
- computer numerical control ( CNC)
computer numerical control ( CNC)
Microprocessor-based controller dedicated to a machine tool that permits the creation or modification of parts. Programmed numerical control activates the machine’s servos and spindle drives and controls the various machining operations. See DNC, direct numerical control; NC, numerical control.
Step that prepares a slug, blank or other workpiece for machining or other processing by separating it from the original stock. Performed on lathes, chucking machines, automatic screw machines and other turning machines. Also performed on milling machines, machining centers with slitting saws and sawing machines with cold (circular) saws, hacksaws, bandsaws or abrasive cutoff saws. See saw, sawing machine; turning.
- edge preparation
Conditioning of the cutting edge, such as a honing or chamfering, to make it stronger and less susceptible to chipping. A chamfer is a bevel on the tool’s cutting edge; the angle is measured from the cutting face downward and generally varies from 25° to 45°. Honing is the process of rounding or blunting the cutting edge with abrasives, either manually or mechanically.
Device, often made in-house, that holds a specific workpiece. See jig; modular fixturing.
- gang cutting ( milling)
gang cutting ( milling)
Machining with several cutters mounted on a single arbor, generally for simultaneous cutting.
Machining operation in which material is removed from the workpiece by a powered abrasive wheel, stone, belt, paste, sheet, compound, slurry, etc. Takes various forms: surface grinding (creates flat and/or squared surfaces); cylindrical grinding (for external cylindrical and tapered shapes, fillets, undercuts, etc.); centerless grinding; chamfering; thread and form grinding; tool and cutter grinding; offhand grinding; lapping and polishing (grinding with extremely fine grits to create ultrasmooth surfaces); honing; and disc grinding.
- grinding machine
Powers a grinding wheel or other abrasive tool for the purpose of removing metal and finishing workpieces to close tolerances. Provides smooth, square, parallel and accurate workpiece surfaces. When ultrasmooth surfaces and finishes on the order of microns are required, lapping and honing machines (precision grinders that run abrasives with extremely fine, uniform grits) are used. In its “finishing” role, the grinder is perhaps the most widely used machine tool. Various styles are available: bench and pedestal grinders for sharpening lathe bits and drills; surface grinders for producing square, parallel, smooth and accurate parts; cylindrical and centerless grinders; center-hole grinders; form grinders; facemill and endmill grinders; gear-cutting grinders; jig grinders; abrasive belt (backstand, swing-frame, belt-roll) grinders; tool and cutter grinders for sharpening and resharpening cutting tools; carbide grinders; hand-held die grinders; and abrasive cutoff saws.
- in-process gaging ( in-process inspection)
in-process gaging ( in-process inspection)
Quality-control approach that monitors work in progress, rather than inspecting parts after the run has been completed. May be done manually on a spot-check basis but often involves automatic sensors that provide 100 percent inspection.
- inner diameter ( ID)
inner diameter ( ID)
Dimension that defines the inside diameter of a cavity or hole. See OD, outer diameter.
Machining operation in which metal or other material is removed by applying power to a rotating cutter. In vertical milling, the cutting tool is mounted vertically on the spindle. In horizontal milling, the cutting tool is mounted horizontally, either directly on the spindle or on an arbor. Horizontal milling is further broken down into conventional milling, where the cutter rotates opposite the direction of feed, or “up” into the workpiece; and climb milling, where the cutter rotates in the direction of feed, or “down” into the workpiece. Milling operations include plane or surface milling, endmilling, facemilling, angle milling, form milling and profiling.
- outer diameter ( OD)
outer diameter ( OD)
Dimension that defines the exterior diameter of a cylindrical or round part. See ID, inner diameter.
- sawing machine ( saw)
sawing machine ( saw)
Machine designed to use a serrated-tooth blade to cut metal or other material. Comes in a wide variety of styles but takes one of four basic forms: hacksaw (a simple, rugged machine that uses a reciprocating motion to part metal or other material); cold or circular saw (powers a circular blade that cuts structural materials); bandsaw (runs an endless band; the two basic types are cutoff and contour band machines, which cut intricate contours and shapes); and abrasive cutoff saw (similar in appearance to the cold saw, but uses an abrasive disc that rotates at high speeds rather than a blade with serrated teeth).
1. Ability of a material or part to resist elastic deflection. 2. The rate of stress with respect to strain; the greater the stress required to produce a given strain, the stiffer the material is said to be. See dynamic stiffness; static stiffness.
Minimum and maximum amount a workpiece dimension is allowed to vary from a set standard and still be acceptable.