the Expert Q:
We have used uroflax type gear coupling in Boiler feed pump - booster pump rotate at 1480rpm and couple between motor & booster pump. We used molycoat 1000 type grease for lubrication purpose, but after some running grease dry and it effect erosion & corrosion of gear tooth and damaged the tooth. So please suggest the proper grease type for lubrication purpose.
A:
Euroflex (UK) and Euroflex India reportedly manufacture non-lubricated flexible disc couplings. Dow Corning Molykote (R) 1000 is an anti-seize paste containing solid lubricants and metal powders, not a coupling grease. Grease-lubricated gear couplings require specialized products that do not readily separate base oil in service. Such products typically contain high concentrations of polymers. Coupling greases are typically not suitable for use in bearings or other applications where greases are normally used. Coupling gear tooth corrosion and damage may indicate inadequate performance of the lubricant, or an excessively long relubrication interval. The interval between grease changes on a grease-lubricated coupling should be adjusted so that the performance of the product does not significantly degrade over the service
period. Factors such as elevated temperature can significantly shorted relubrication intervals. Seizing of Threaded Couplings A frequent complaint expressed about stainless steel fasteners an other threaded couplings is the problem of seizing. The problem is frequently not that of the material itself but more than likely caused by mismatched threads, Nonuniform threads, an dirt on threaded surfaces. Reasonable care should be exercised in the handling of fasteners to prevent damage and to keep threads clean. Fasteners made in accordance with nationally recognized standards, such as published by the American National Standards Institute, Inc. (ANSI), will assure that nuts and bolts are uniformly threaded. Torque should also be considered for a properly fastened joint. Suggested maximum torque values for stainless steels are published in the booklet “Stainless Steel Fasteners A Systematic Approach to Their Selection.”, copies of which are available from the Committee of Stainless Steel Producers. Nevertheless, galling may occur in clean, carefully machined threads, and it may be desirable to use a lubricant if another alloy material either cannot be used or is not available. If a lubricant is going to be used with threaded fasteners, tests should be conducted to determine torque
- 50 VOLUME 80, NUMBER 4
