When considering proper pre and post cleaning of parts, quality is just one consideration for captive heat treaters and commercial shops. The other is the damage that both vacuum and atmospheric furnaces can incur, leaving shops with costly problems to their equipment including: loss of vacuum, contamination to future runs, smoke bombs and shortened quench oil life.
Vacuum Furnaces
3 major manufacturers of vacuum heat treatment equipment stress the importance of a comprehensive preventative maintenance program – one that includes the need for properly cleaned parts, baskets and fixtures. Here is why;
- Dirty parts can increase the rate at which the hot zone deteriorates
- Contaminants with high vapor pressures will evaporate during heating, causing loss of vacuum
- Vapors may eventually condense on colder surfaces in the furnace – re-vaporization can cause contamination problems in future production runs
- Parts that are not cleaned and thoroughly dried may have solvent or water residues, which will volatilize during heat treating and degrade pumping performance
It may also be worth checking the manufacturer’s warranty – furnace problems caused by dirty parts may void the warranty or cause a claim to be rejected.
Atmospheric Furnaces
According to subject matter experts cited in Heat Treat Today, the need for cleaning is the same for both captive heat treaters and commercial job shops that use atmospheric furnaces;
- Proper pre-cleaning protects the heat treat equipment from contamination and ‘smoke bombs’, provides a clean, uniform surface for parts processing, and directly affects the success of the heat treatment process.
- Proper cleaning in between quench and temper will assure consistent post process cleanliness and reduce/eliminate smoke emissions. It will also ensure that the final part meets the customer quality specifications.
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