High-Speed Cutting for Small Precision Parts
Manufacturing Engineering, Jim Lorincz - Senior Editor
Dau Thermal Solutions Inc. (Macedon, NY) was finding that its spindle speeder was definitely not up to speed when it came up against the test results for NSK’s HES510 series electric spindle. The company specializes in the design and manufacture of quality, cost-effective, high-performance heatsinks for medium through high power applications. With over 26 years, experience, Dau takes designs from the conceptual design stage through prototypes and into production and provides its customers with the largest selection of engineered thermal management solutions for power electronics in the industry.
For the fastest growing segment of the thermal management world, Dau offers the latest cold plate technology with the largest selection of high-performance, engineered liquid-cooled solutions. For air-cooled heat sinks, Dau offers a wide range of heatsink solutions manufactured from extrusions to the highest performing all copper-soldered fin designs. For moving heat, Dau manufactures heatpipes for power electronic applications from 8 mm through 25 mm in diameter.
After three years of using another builder’s spindle speeder, Dau Thermal had begun losing confidence in the product and decided to look for a replacement for its high-speed machining. Initially at Dau’s facility, a spindle speeder was installed into a Haas VF Super Speed VMC with a 0.040″ (1-mm) diameter end mill. The machining center was milling about 30 channels into an 8 × 5″ (203 × 127-mm) copper workpiece, and encountering issues when speeds were increased. The air spindle started out running close to 30,000 rpm and only cutting at a 0.002″ (0.25-mm) depth of cut at 100 ipm (2.54 m/min) with a 9 min 30 sec cycle time. However, when the depth of cut increased to 0.004″ (0.100 mm), the spindle stalled and very heavy burrs were produced.
To answer the question about how much auxiliary electric spindles would increase machining speed of Dau’s existing machines without interrupting machine operation, Dau Thermal Solutions invited NSK America Corp. (Hoffman Estates, IL) to demonstrate their HES510 Series Electric Spindles.
When NSK’s HES510 spindle was introduced, it was programmed to duplicate the specs of its rival spindle speeder. The load meter sensor on NSK’s control barely blinked in reaction. NSK took it to a 0.004″ (0.100-mm) depth of cut at 40,000 rpm and still no reaction from the sensor. With a 0.006″ (0.150-mm) depth of cut at 50,000 rpm, the sensor only flickered slightly and the spindle remained steadfast. In total, NSK performed 12 different test cuts in three hours at Dau Thermal. Using the same tool, Dau Thermal finally settled on NSK’s HES510 with a 0.010″ (0.25-mm) depth of cut at 200 ipm (5 m/min) and 50,000 rpm. Cycle time came in at just 2 min 40 sec, and has since been reduced. Also, no burrs were produced at all.
“Compared to our previous spindle speeder, the HES510 provided more torque, maintained rpm and reduced cycle times by 50–75%,” said Dau Thermal Solutions’ president and CEO, Robert Krochmalech. The HES510 operates on its own power via a self-contained brushless DC electric motor with 340-W maximum output. It can push tools in 1000-rpm increments all the way to 50,000 rpm (NSK’s HES810 reaches 80,000 rpm).
Fewer passes were required to complete the job, resulting in less wear and tear on the tool. Damage to tooling is also prevented through the HES Series’ concentricity of less than 1 μm. Superior to a speeder, we want to run small cutters where concentricity is controlled so the cutter doesn’t break,” said Chris Rezny, sales manager, NSK America Corp.
And remember that little problem of stalling? Gone. Because the HES Series features a completely self-contained motor, chips, mists, and other debris don’t penetrate the operating mechanism and don’t interrupt machining. Those contaminants not only stalled the previous speeder, but often put it out of commission.
“Our former spindle speeder sucked in chips so we would need to send it to Japan to be rebuilt. Service would take up to four weeks,” said Krochmalech. “The HES is serviced locally in the US and is a more robust unit.” Rebuilding the speeder cost not only time, but money as well. “We blew their socks off. Dau Thermal realized that it was cheaper to buy new from us than to repair their spindle speeder,” said Rezny. “Other advantages of the HES Series include full operator control of the rpm range and built-in spindle cooling. NSK’s no-cost demonstration program allows new and existing customers to test their products for up to seven days.”
Edited by Senior Editor Jim Lorincz.
This article was first published in the October 2016 edition of Manufacturing Engineering magazine.