Drip carburizing:
This method uses a neutral gas which will not affect the metal surface, into which are introduced CO, propane, butane or metane vapours. The latter may be done by allowing a liquid hydrocarbon to drip, at a controlled rate, into the furnace atmosphere so that it vapourizes and releases its constituents which can react with the metal surface. This process is known as drip carburizing.
(Materials science, G. K. Narula, K. S. Narula, V. K. Gupta, p.195)
Rank Order Clustering (ROC) Algorithm:
This algorithm was developed by J. R. King (1980) to determine machine-component cells in group-technology. Group technology is a layout system used in industries, which combines the benefits of process layout and product layout. This algorithm considers the following data,
1. Number of components
2. Component sequences
Based on the component sequences, a machine-component incidence matrix is developed. The rows of the machine-component incidence matrix represent the machines which are required to process the components. The columns of the matrix represent the component numbers.
(Design and Analysis of Algorithms, Panneerselvam, p.37)
Jet Plating:
The most outstanding application of jet plating is in the electronics industry for the selected-area plating of lead frames on reel to reel plating machines. The most important metals are gold and silver but nickel plated from sulphamete baths is often used as an undercoat. Fast rate plating is achieved by impinging a jet of solution onto a localized area defined by a gasketed (mask) template. Multi-layer coatings can be deposited sequentially using this technique. Thin coatings with good distribution can be achieved in a very economical manner.
Raub has developed a cell for simulating high-speed electrodeposition by jet plating. Results are published for the deposition of chromium and palladium/nickel alloys as well as for other metals. In the case of chromium the mixing of the electrolyte is not solely due to hydrodynamic flow but also to stirring by gas bubbles. Comparative information is given for palladium/nickel alloys deposited by jet plating and rotating cathode techniques. Bocking has reported the results of high speed selective jet electrodeposition. The purpose of this research is to achieve direct writing of electrical and electronic devices. Simon has also described laboratory experiments which made use of high velocity jets of electrolytes for deposition of hard gold coatings at current densities ip to 50 A/dm^2.
(Nickel and chromium plating, J. K. Dennis,T. E. Such, p.429)
Shell moulding:
It is a process in which, a thin mold is made around a heated metallic pattern plate. The moulding material is a mixture of dry, fine silica sand (clay content should be kept very low), and 3-8% of a thermosetting resin like phenol formaldehyde or ureaformaldehyde. Conventional dry mixing techniques are used for obtaining the moulding mixture. Specially prepared resin coated sands are also used.
When the moulding mixture drops on to the pattern plate, which is heated to a temperature of 35 to 700 F, a shell of about 6 mm thickness is formed. In order to cure the shell completely, it must be heated to 440 to 650 F for about 1-3 minutes. The shell is then released from the pattern plate by ejector pins. To prevent sticking of the baked shell to the pattern plate, a silicone release agent is applied to the latter before the moulding mixture drops on to it.
Shell moulding is suitable for mass production of thin walled, grey cast iron (and aluminum alloy) castings having a maximum weight between 35 and 45 pounds. However, castings weighing up to 1000 pounds can be made by shell moulding on an individual basis. The advantages of shell moulding include good surface finish, fewer restrictions on casting design, besides rendering itself suitable for automation.
(Product Design and Manufacturing, A. K. Chitale,R. C. Gupta, p.90)
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