Generic vibration criteria for vibration-sensitive equipment
The vibration criterion (VC) curves, commonly used in the design of facilities which house vibration-sensitive instruments and tools, were developed by the author and his colleagues, in the early 80's, published by SPIE in 1991 and by IEST in 1993. Each of the criterion curves A through E is associated with a 'line width' or 'detail size' which was an attempt by the authors to describe the capabilities of the tools with which each curve might be associated. In the years since the curves were developed there have been substantial developments in tool design and isolation. In this paper the curves are reviewed in the context of present-day tools and processes. Changes are proposed where these might be justified.
Generic criteria for vibration-sensitive equipment
When designing facilities for research, microelectronics manufacturing and similar activities, it is generally necessary to have vibration criteria which are generic (i.e., applicable to classes of equipment and activity) rather than specific to particular items of equipment. This paper describes the derivation and use of one such set of criteria that is based on one-third octave band vibration velocity spectra. The paper also discusses the need to develop methods and standards for measuring the vibration sensitivity of equipment. Some examples are given which illustrate the considerable confusion in equipment sensitivity standards that exists at the present time. A plea is made to equipment manufacturers and users to develop and call for, respectively, specifications that are real and precise. This is especially important as the high- technology community enters the ''age of the nanometer.''
Determination of Optimal Ball-Burnishing Parameters for Plastic Injection Moulding Steel
The objective of this study is to determine the optimal plane ball-burnishing parameters for plastic injection moulding steel PDS5 on a machining centre by utilising the Taguchi’s orthogonal array method. The design and manufacture of a burnishing tool are described. Four burnishing parameters, namely the ball material, burnishing speed, burnishing force and feed, were selected as the experimental factors in Taguchi’s design of experiments to determine the optimal burnishing parameters which have the dominant influence on surface roughness. The optimal burnishing parameters were found after carrying out the experiments specified by Taguchi’s L18 orthogonal table, by the analysis of variation, and by a full factorial experiment. The optimal plane burnishing parameters for the plastic injection moulding steel PDS5 were a combination of a tungsten carbide ball, a burnishing speed of 200 mm/min, a burnishing force of 300 N and a feed of 40 μm. The surface roughness Ra of the specimen can be improved from about 1 μm to 0.07 μm by using the optimal burnishing parameters for plane burnishing.