Special Procedures for the Removal of Grinding Honing and Lapping Compounds

Residues remaining on parts after honing or grinding are usually mixtures of metallic and abrasive particles with oil-based or water-based cutting fluids. Thus, the methods recommended earlier in this article for the removal of chips and cutting fluids are applicable also for the removal of grinding residues in a majority of instances.

Lapped parts are usually more difficult to clean than honed or ground parts. Lapping residues are composed of extremely fine particles of various abrasives, minute metal particles, semi-solid greases and oils, and some graphite. Even if graphite is not a part of the original lapping compound, it accumulates from the wear of cast iron laps. Allowing compounds to dry increases cleaning difficulty. In many instances, methods used for removing polishing and buffing compounds are applicable also for removing lapping compounds. However, parts that are precision ground, honed, or lapped present special cleaning problems because: such parts are commonly used in precision machinery, and consequently the degree of cleanness required is higher than for most commercial work; they are frequently intricate in design (an example in Part 15 in Fig. 3); and they are commonly susceptible to damage and frequently require special handling.

Fig. 3 Part for fuel control mechanism that requires special modification of solvent cleaning to remove grinding and lapping compounds

An extremely high degree of cleanness without damage is required on some expensive delicate parts (e.g., fuel injection equipment). Ultrasonic cleaning with alkaline solution, followed by spray with alkaline and immersion/spray rinsing is ideal for this application. Ultrasonic cleaning is rapidly replacing the old pressure solvent spray/agitated immersion technologies, which were only partially effective. Parts which normally took an hour or more to clean using solvent cleaning processes are now effectively cleaned in just a few minutes of ultrasonic cleaning. Other inherent advantages of this approach are that it is nondestructive to the parts; it uses more environmentally friendly cleaning solutions, and it is much safer with respect to the explosion dangers that are characteristic of many solvent cleaning technologies. As always, the primary drawback to ultrasonic cleaning is the comparative high up-front capital cost.

0 0

Post a comment