Vac Cad plating problems and fatigue failures in H-11 tool steel
We process H-11 tool steel threaded parts and we are achieving fatigue results of 300,000 cycles and more prior to Vac-Cad plating. The parts are then sent to the plating company and lightly blasted with low pressure using glass bead or aluminum oxide. We have found that over the years we have had better luck with the Glass Bead and we have tried different platers. The problem is, we still are experiencing too many failures. We require 65000 cycles at final testing and we are not even meeting that. The finish on these parts are more rough after the plating. We can see this through metallurgical evaluations. Is there another way to pre-treat these parts prior to plating and still achieve the adhesion? We must plate to MIL-C-8837 and we would prefer not to acid clean unless it is more beneficial. Is the time between plate and post bake as critical as the cad plate per QQ-P-416 [link by ed. to spec at Defense Logistics Agency, dla.mil] ?
Thanks,Don J. Huffman
- Torrance, California, USA
The VacCad plating process should not reduce the fatigue strength of the steel but your preparation treatment may. Have you tested the fatigue strength after preparation but before VacCad plating?
Society of Vacuum Coaters
Albuquerque, New Mexico
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No we have not tested fatigue prior to plating as the spec requires that plating shall be done immediately after abrasive pre-clean and the parts are not plated at our facility, but at an outside source. Can you recommend a pre-clean light blast prior to plate? We have tried Aluminum Oxide and Glass Bead.Don Huffman
- Torrance, California USA