Sand casting is by far the most widely used casting process, accounting for a significant majority of the total tonnage cast. Nearly all casting alloys can be sand cast; indeed, it is one of the few proceses that can be used for metals with high melting temperatures, such as steels, nickels and titaniums. Its versatility permits the casting of parts ranging in size from small to very large and in production quantities from one to millions. Sand casting consists of pouring molten metal into a sand mold, allowing the metal to solidify and then breaking up the mold to remove casting. The casting must then be cleaned and inspected and heat treatment is sometimes required to improve metallurgical properties.
(M. Groover, Fundamentals of Modern Manufacturing; Page: 215)
Automated Flow Lines
Automated production line consists of automated workstations connected by a parts transfer system whose actuation is coordinated with the stations. In the ideal, no human workers are on the line, except to perform auxiliary functions such as tool changing, loading and unloading parts athe beginning and end of line and repair and maintenance activities. Modern automated lines are integrated systems, operating under computer control.
(M. Groover, Fundamentals of Modern Manufacturing; Page: 930)
Infinite Life Design
Unlimited safety is the oldest criterion. It requires local stresses or strains to be essantially elastic and safely below the pertinent fatique limit. For parts subjectedto million cycles, like engine valve springs, this is still a good design criterion. However, most parts experience significant variable amplitude loading and the pertinent fatigue limit is difficult to define or obtain. In addition, this criterion may not be economical or practical in many design situations. Expamles include excessive weight of aircraft for impracticality and global competitiveness for cost effectiness.
(Ralph I. Stephens, Metal Fatigue in Engineering, 2nd Edition; Page: 23)
Safe Life Design
The safe life must include a margin for the seatter of fatgue results and for other unknown factors. The calculations may be based on stress-life, strain-life or crack growth relations. Safe life design may be based solely or partially on field and simulated testing. The margin for safety in safe life design may be taken in terms of life, in terms of load or by specifying that both margins must be satisfied.
(Ralph I. Stephens, Metal Fatigue in Engineering, 2nd Edition; Page: 23,24)
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