Machining and Surface Finishing

In the United States, the following specifications are commonly used as standards and references in dimensional measurement and surface roughness evaluation  

ASME ANSI B46.1-2002 Surface Texture, Surface Roughness, VJaviness, and Lay 

ASME Y14.38 Abbreviations and Acronyms for Use on Drawings and Related Documents 

The following international standards are also frequently referenced in surface roughness International Standards Organization ISO 1302 2002 and Australian Standards AS ISO 1302-2005. These standards measure surface roughness with specifying parameters in various ratings. 

Equation 5.2a and b, respectively, where L and A are the length and area of interest, and Z(x) and Z(x, y) are the profile heights at individual surface locations. 

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Table 18.3 Data from (ALO3) Stokes, R.J. (1972) The Science of Ceramic Machining and Surface Finishing, NBS Special Publication 348, U.S. Government Printing Office, Washington, D.C., p. 347. (SiC) Richerson, D.W. (1992) Modern Ceramic Engineering, 2 Ed., Marcel Dekker, New York, p. 170.

Andersson, C.A. and Bratton, R.J., 1979, Effect of surface finish on the strength of hot pressed silicon nitride, in The Science of Ceramic Machining and Surface Finishing n, NBS Special Publication 562, pp. 463- 76. 

The Science of Ceramic Machining and Surface finishing, NBS Special Publication 348, p. 37. 

Rice, R.W. and Mecholowsky, J.J., "The Nature and Strength Controlling Machining Flaws in Ceramics," Symposium on the Science of Ceramic Machining and Surface Finishing II, NBS Publication 562,1979, pp. 351-378. 

All potential sources of defects will be evaluated, from raw materials through individual [X)wder processing and densification steps and finally through machining and surface finishing of the lest specimen. 

Imanaka, O., Okutomi, M., 1979. New Concepts on surface finishing and its application to ceramics. Proc. 2nd Int. Symp. on Science of Ceramic, Machining and Surface Finishing. 

New machining techniques are constantly being introduced. Conventional workpiece materials have improved progressively through close control of manufacturer and heat treatment, and new materials have been fostered by the aeronautic and space industries. The results have been ever improving output, dimensional control and surface finish. The continuous development of cutting fluids has enabled these increasingly severe conditions to be accommodated. 

The mold can be modified to meet certain different shapes. The molding can be made either by withdrawing cores or by special press motions that partially open the mold halves (such as the compression molds used in coining to provide 2-D action 3-D mold actions are also used). The degree of foam density, wall thickness, and surface finish depends on the foam mixture (constituents and amounts). The machine controls the time cycle and the mold action required. 

The third main step of combustion synthesis technologies is postsynthesis treatment. This step is optional, since not all products require additional processing after synthesis. Powder milling and sieving are used to yield powders with a desired particle size distribution. Annealing at elevated temperatures (800-1200°C) removes residual thermal stress in brittle products. The synthesized materials and articles may also be machined into specified shapes and surface finishes. 

Electrochemical machining (ECM) is a method of metal machining that aims at producing parts of specified shape, dimensions, and surface finish. The process is based on the removal of metal by electrochemical dissolution ([1-15] and references cited therein). Special machines have been developed to realize this aim. A complete ECM installation (Fig. 1) consists of the machine, the power supply, the electrolyte circulation system (tank, pump, heat exchanger, and sludge removal unit), and the control system (control of current, voltage, feed rate, gap width, and electrolyte temperature, pH value, pressure, and concentration short-circuit protection). 

In ECM sinking, the accuracy and surface finish depend considerably on the proper choice of TE design, a scheme of electrolyte feed through the slots and holes into the machining zone, the scheme, and parameters of machining. ECM sinking is... 

Depending on the operating conditions and metal-electrolyte combinations, different anodic reactions take place when sufficient pulse power is applied. Rate of anodic reactions is influenced by the supply of fresh electrolyte, which enables the removal of reaction products as soon as they generates into the machining zone. The electrolyte flow velocity is negligible in case of EMM. So there is not sufficient transfer of mass from one electrode to the other. This gives rise to the formation of diffusion layer at the electrode-electrolyte interface at anode. Machining performance e.g. MRR, accuracy and surface finish of the workpiece is affected by the factors as discussed already. 

Texturing and removal of contact-machined directional surface finish and subsurface damage... 

Equipment and materials are more expensive than those required in sand casting and therefore require the production of larger quantities to be economic. The higher costs for small quantities can, however, often be offset by savings as a result of the ability to produce a high degree of dimensional accuracy and surface finish which can reduce or eliminate subsequent machining operations. 

Addition of Se improves the machinability of stainless steels and assists when corrosion resistance, hot and cold formability, and surface finish are important. Also, selenium vulcanization may be used where improved product aging performance or heat resistance is desired [1]. 

Lighter sections to be specified by overcoming the problems of force fits, etc Reduction in machining time as tolerances are not so tight and surface finish not so important ... 

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