Creepfeed (CF) grinding is not generally well understood. Those who are familiar with it, however, have found it an attractive alternative to other machining processes--milling or broaching, for example.
According to Ken Kummer, CEO, Abrasive-Form Inc., Bloomingdale, IL, creepfeed grinding can be used to produce part volumes from a single part per day to up to 50,000 a day. Abrasive-Form is a contract manufacturer that specializes in creepfeed grinding. It processes just about any material that can be ground: aluminum, cold rolled steel, high-nickel alloys, hardened materials, carbide, tool steels, and ceramics.
Typical applications include aerospace engine components, power generation, land-based turbines, automotive engine and drive train components, tiny medical parts, consumer products, and parts for the packaging, hand tool, paper and pulp industries as well as the military. Typical tolerances are 0.0005", while many are routinely [+ or -] 0.0002". Cpks of 1.33 are the rule.
Kummer says that the trouble with creepfeed grinding is that too many people have either never heard about it, or simply don't understand it (this despite the prolific editorial efforts of Dr. Stuart C. Salmon, the technology's revered expert). Even those who are familiar with the discipline very often overlook important nuances, which, taken into account, can be turned into significant competitive advantages.
Begin with basics
Grinding as a manufacturing process entails a greater number of variables than, perhaps, any other metal removal process. Machine rigidity, stability, and repeatability, wheel materials and characteristics, dressing systems, cool ant types and application, fixturing, gaging--all must work perfectly in concert to produce the desired result.
Surface grinding--involves a grinding wheel reciprocating rapidly over the work-piece as it gradually lowers to its final depth of cut. CF is a process in which a formed grinding wheel is plunged full depth into the workpiece, effectively producing a finished part in a single pass. Its advantages include Fast cycle times, high repeatability, very close tolerances, and the ability to machine super alloys as well as fully hardened materials and superior surface finish with essentially burr-free edges.
CF requires machines specially designed for the process, machines with serious rigidity and power. Kummer's machines of choice: Magerle and Blohm, both from United Grinding Technologies, Miamisburg. OH.