Why turn when you can grind?

Published
May 23,2021 - 08:00pm

Related Glossary Terms

  • grinding

    grinding

    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

    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.

  • grinding wheel

    grinding wheel

    Wheel formed from abrasive material mixed in a suitable matrix. Takes a variety of shapes but falls into two basic categories: one that cuts on its periphery, as in reciprocating grinding, and one that cuts on its side or face, as in tool and cutter grinding.

  • turning

    turning

    Workpiece is held in a chuck, mounted on a face plate or secured between centers and rotated while a cutting tool, normally a single-point tool, is fed into it along its periphery or across its end or face. Takes the form of straight turning (cutting along the periphery of the workpiece); taper turning (creating a taper); step turning (turning different-size diameters on the same work); chamfering (beveling an edge or shoulder); facing (cutting on an end); turning threads (usually external but can be internal); roughing (high-volume metal removal); and finishing (final light cuts). Performed on lathes, turning centers, chucking machines, automatic screw machines and similar machines.

Why turn when you can grind?

The Grindstar profile and cut-off machine.The Weifuautocam Precision Machinery Corporation from Wuxi, China is using a Grindstar profile and cut-off machine from Junker for the production of adjusting screws for high-pressure hydraulic pumps.

Weifuautocam, a part of the Weifu Group, began collaborating with Junker in 2000. Since then, Junker has worked on a variety of applications for the company from grinding turbine pumps to common rail pumps. Ding Yu, project manager at Weifuautocam, said the company continually searches for better and faster machines, and, during a visit to the EMO 2017 trade fair they learned about the Grindstar.

Profile and cut-off grinding machine

Weifuautocam uses the Grindstar for producing adjusting screws for high-pressure hydraulic pumps used in vehicles with turbochargers – one of the technologies that meets the latest national VI emissions standards.

From left to right: Ding Yu, project manager, and Ge Wei, production engineer both of Weifuautocam; and Sun Wenlai, area sales manager of Junker Shanghai Representative Office. Source: Junker"Our products can be found in injection nozzles for vehicle engines, high-pressure pumps and magnetic gearbox valves,” said Ding Yu. “Our production always runs in three shifts per day. Quality and speed are our most important standards.

The machine uses two machining methods: profile grinding and cut-off grinding. The essential synergy effect is achieved by combining the two methods in a single clamping set-up. The Grindstar replaces several lathes, particularly in the context of mass production. The direct machining of bar stock, with a length of up to four meters, or six meters optionally, nounkert only increases efficiency, but also the surface quality of the workpiece.

"It was a decisive factor for us that the grinding wheel does not need to be dressed,” said Ge Wei, production engineer at Weifuautocam. “Operating the machine is made simple thanks to minimal settings. The machine is also equipped with an in-process measuring system, which thanks to a stable quality, enabling us to achieve virtually unmanned operation."

Reliable service

After the EMO show, Weifuautocam opted for the Grindstar and became the first owner of this technology in China. "Grinding as opposed to turning is a sophisticated technology developed by Junker,” said Ding Yu. “Investing in a well-developed technology has paid off for us, enabling us to start with production earlier and to position ourselves on the market. Throughout the longstanding collaboration between Weifu and Junker, we have been impressed by the Junker quality."

Grindstar can achieve the shortest machining times. This novel grinding process can be used with both CBN and diamond as an abrasive. Source: JunkerThe Junker Asia Service Center had already planned the commissioning thoroughly in advance of the arrival of the machines. A service technician was specially trained in the setup and carrying out initial machine tests. "After the arrival," said Ge Wei, "we realized that the room temperature of our workshop deviated from the required machine standard ambient temperature. The Junker engineer provided us with training and supported us in carrying out the relevant optimizations and improvements so that we were able to meet the conditions for normal machine operation."

For more information on Junker products, visit www.junker-group.com.