“The major difficulty that may be encountered in machining die castings is the soldering of the metal to the cutting edge of the tools. This condition can be minimized by setting the tools correctly, providing proper rake and clearance angles, polishing the tool surfaces or clearance spaces, avoiding drag by reducing the tool in contact with the work, using the proper lubricant, and choosing the correct machining speed in relation to the feed.
Plenty of chip room is required on all tools to provide a free cutting action and to prevent excessive loading or packing of chips. Light cuts should be avoided as much as possible. The cut should be deep enough to penetrate the outer surface of the die casting metal; this outer surface tends to be harder than the base metal because of its abrasive content and therefore it is advisable to remove at least .005 to .010 in. of stock whenever possible on the die casting. Lubricants and/or coolants generally are required when close tolerances, improved speed of production and fine finishes are necessary. A lubricant is necessary for all operations when machining die castings except turning when machining aluminum.”
Doehler, H.H. (1951) Die Casting. New York, New York. McGraw-Hill Book Company, Inc.