Steel chains must be "oil coated" to ensure lasting strength and rust-free delivery. Until about two years ago the chains were immersed in a steam heated tank containing a light oil at about 90°F. The initial results were good, but this low viscosity oil tended to drain away from the journals during warehousing. Corrosion became an increasing problem as storage time lengthened. Also, the oil's value as an initial lubrication decreased.
A more viscous oil was the answer because it would not drain off. However, for proper application and good penetration it had to be heated to about 200°F. This higher temperature could not be obtained with steam in the existing tank.
A new, insulated tank was built and equipped with 9 Chromalox immersion heaters, 6 kW each, and automatic controls. This provided the higher temperatures required --accurately and safely. All heaters are energized during heat-up but only four are needed during operation. Inside the tank, the heaters are protected during loading and unloading by a steel grate which does not interfere with the circulation of the oil. The oil is maintained at a temperature of 200° F and the automatic controls also provide an over-temperature limit of 270° F. A single operator can now treat up to 80,000 lbs. of roller chain in an 8-hour day. Results are much better and corrosion of chains is no longer a problem. The only maintenance during two years of operation has been one cleaning to remove sludge from tank walls and heaters.
- Safe -- no danger of oil reaching flash point temperature.
- Automatic controls bring oil up to operating temperature without attendance.
- Maintenance of heaters is zero.
- Processed parts are now fully protected.
- No excessive heat to disturb personnel.
- Production has been increased.