The research of high-quality grinding technology of large-size Al2O3 single-crystal slice
Al<inf>2</inf>O<inf>3</inf> single crystal has the following unique physical properties of high hardness, high toughness, obvious pleochroism and high refractive index Etc. The paper introduced the processing property of Al<inf>2</inf>O<inf>3</inf> single crystal, described its grinding technology. Then analyzed the characteristics and status of grinding technology of the large-sized Al<inf>2</inf>O<inf>3</inf> single crystal, combined with the relational research, discussed the technology of the grinding stage. Finally the paper summarized a set of precise grinding technology of large-sized Al<inf>2</inf>O<inf>3</inf> slice.
A new approach for the characterization of machinability—application to steels for plastic injection molds
Abstract An economical analysis of the plastic injection market highlights the necessity to increase productivity. Mold steel influences the total cost of an injected part more through its capability to be worked than through its own price. Among the mold manufacturing operations, rough and finish machining are two of the most expensive, depending strongly upon the mold steel machinability. A new method has been developed to compare the machinability of three 300 HB mold steels during rough milling. Based on a half-fractional design of experiments, a new model is proposed which takes into account material variation, as well as cutting parameter interactions. The application of this approach has shown the interest of a new redesigned grade presenting high surface properties, which could be as machinable as a high sulfur content grade which presents limited surface finishing capabilities.
Machinability of calcium-treated steels using TiN-coated high-speed steel tools
AbstractTurning tests were carried out with TiN-coated and uncoated high-speed steel (HSS) inserts. The workpiece materials consisted of steels corresponding approximately to AISI 4140 and AISI 8620. In addition to the standard grades, calcium-treated variants of each steel were studied. The calcium-treated grades produced from 15 to 80% longer lifetimes than the standard grades when cut with uncoated HSS tools. When the tools were TiN-coated, the lifetimes with calcium-treated grades increased from 40 to 500%. Energy dispersive X-ray spectrometry revealed increased amounts of elements including manganese, calcium, silicon, and sulphur on the surface of the TiN-coated tools, indicating the formation of a non-metallic protective layer on the tool surface, which is suggested as an explanation for the observed increase in the wear resistance.MST/565