Manufacture of nanocrystalline metals by machining processes

Purpose: The paper shows how extremely high-speed micromachining can be used as a method for manufacturing nanocrystalline feedstock from machining chips. The feedstock can be used in processes such as cold spraying that improve the surface characteristics of engineering components. Design/methodology/approach: The design and methodology relies on the construction and the correct operation of a micromachining operation that produces functional feedstock material that is produced from machining chips at spindle speeds in excess of half-a-million revolutions per minute. The approach provides an economical way of producing metal nanocrystals. Findings: The findings of the research show that intense plastic shearing of metals produces nanosized crystals in the range 30nm to 150nm. The crystals produced can be used to create superior functional coatings on engineering components. Research limitations/implications: The research conducted implies that a cost effective and environmentallybenign process can produce metal nanocrystals. The limitations of the research are currently restricted to cold spraying of functional surfaces. Practical implications: The practical implications of the research show that high-speed micromachining can be used as a method of producing nanocrystalline feedstock that can be used in a variety of secondary manufacturing processes in addition to cold spraying. Originality/value: The paper demonstrates the originality of using well-established machining processes for producing nanocrystalline metals. The paper describes how machining at extremely high speeds can be achieved to produce material that can be used to strengthen and harden engineering components.