Grinding

Many times in making parts for aerospace engines with high temperature alloys like IN-718, Rene-95 and Waspaloy it is necessary to remove large amounts of material. Traditionally companies use, milling, turning or broaching to remove most of the material and then finish-grind to size. The engineers at Norton/Saint-Gobain's Higgins Grinding Technology Center have determined that for these materials grinding can, in many instances, remove the material more quickly and economically than turning or milling.

Whether you are grinding HSS or Tungsten Carbide, the flute grinding process is the most difficult feature to grind in round tool manufacturing. Though there are many reasons why, the main reason is that this operation is where most material is being removed from the tool, introducing the most heat and spindle load. There are several techniques that can be used to allow the grinding wheel to perform this operation more effectively.

A machinist who is cylindrical-grinding threads into hardened steel using multiple-rib, vitrified-bond, aluminum-oxide wheels is experiencing breakdown of the thread root, and turned to the Grinding Doc for help.

The Grinding Doc offers an upbeat take on tri-grit wheels.

When grinding complex cutting tool profiles, attention should be paid to the software, the wheel and the tool blank for best results.

Dr. Jeffrey Badger, who authors the Ask the Grinding Doc column, answers questions about barreling and scrubber nozzles.

Dear Doc: I battle burn and long cycle times when grinding ODs in bearing. The wheel manufacturer has specified a series of wheel changes to solve the problem, but it means buying a lot of new wheels. What's your take?

A technique I call roll grinding is used to finish corners to match bend radii. Long weld seams that need to be rounded can be handled using a rolling technique with the disc grinder. It takes a little practice, but once you've mastered it, the results look just like a formed corner.

Dr. Jeffrey Badger, Cutting Tool Engineering's Ask the Grinding Doc columnist, cautions readers not to be timid when slowing the workpiece speed to induce burn.

The sweet spot is where the grits in a grinding wheel optimally penetrate the workpiece to form a chip -- not too deep and not too shallow.