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Electro-plated superabrasive grinding wheels are gaining popularity in the areas of high-speed machining. They can now be found in the tool banks of multi-axis milling machines, used in the machining of relatively soft, stainless steels and nickel and cobalt based superalloys. These materials not only cause significant wear of the abrasive grain but moreover, tend to clog and load the grinding wheel, rendering it prematurely inoperable. A means of extending the life of an electro-plated wheel is therefore needed when grinding these "gummy" materials. The use of coatings to improve the performance of cutting tools for use in "large chip" machining like turning, milling, drilling and tapping applications has been shown to be successful, and is widely used. Initially, the coatings provided some wear resistance. Later, coatings were developed for thermal insulation and oxidation resistance. Lately, hard lubricant coatings have shown promise, particularly when used in dry and quasi-dry machining applications. The wear resistant coatings of titanium nitride and titanium carbide have been explored with little success in abrasive machining and grinding applications, in industry. The wear resistant coatings used in "large chip" machining never found a place in "small chip" grinding processes. This paper explores the effects of hard lubricant coatings in industry as well as in the laboratory using both force and power measurement for process evaluation. The results show that a significant improvement may be made in electro-plated cBN wheel performance using a hard lubricant coating system, particularly when grinding the soft and low machinability index materials typically used in the medical and aerospace industries.

PurposeThe purpose of this paper is to investigate the effectiveness of locking or staking of fasteners with epoxy material systems to prevent loss of preload in aerospace environments.Design/methodology/approachA quantitative experimental method is adopted to evaluate epoxy material systems for staking of fastener assemblies subjected to varying dynamic and thermal loads. A statistical design of experiments is employed to probe specific design parameters.FindingsResults show that epoxy application can provide satisfactory fastener locking under a variety of service conditions. It is found that: Epon 828 epoxy provides superior fastener locking compared to 3M Scotch‐Weld Epoxy 2216; epoxy application around screw threads is more effective than application around screw head; and abrading the plate surfaces with 180 grit SiC paper is not an effective or useful surface preparation technique.Research limitations/implicationsThe paper is limited to two commercial epoxy material systems and does not consider important qualitative considerations for industrial use such as cure time and viscosity.Practical implicationsThis and future paper may form the basis of new standards for epoxy staking in the global aerospace industry.Originality/valueThis paper is believed to be one of the very few original experimental studies of fastener staking available in the open literature.

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