Manufacturing Technology- Machining-2
Posted : August 22, 2004 at 9:01 am [IST]
GENERAL TRENDS IN MACHINING
” Production of near-net-shaped components through improvement in basic forming processes of forging, and casting thereby reducing the amount of material removal or eliminating the need for the machining of certain surfaces.
” Maximum metal removal rate with maximum cutting parameters - speed, feed, and depth of cut (DOC).
” Single setup for rough and finish machining. Systems withstand the heavy roughing cuts on raw stock and also allow the precision finishing operation in same setup.
” Multi-tasking machine tools carry out all machining operations on a part on single machine tool in ideally one loading without taking it off to carry out additional operations on separate machine tools and reduce the number of workstations for completing the part.
” Improved accuracy of traditional roughing process such as turning to replace grinding, or improved drilling to eliminate hollow mill or reaming. Simultaneously, traditional finishing process such as grinding is being used for high metal removal with high speed or creep feed.
” Hard-machining of parts up to Rc 65 and above to eliminate some abrasive machining operations.
” Improved cooling of tool-work interface with flood cooling, high pressure/ high volume coolant application. Better coolant-management to abide by environmental legislations.
” Dry machining with no or minimal coolant for reduced cost.
” Just-in-time production for minimum inventory cost, reduced manufacturing lead time, better delivery performance, lesser space requirement with improved delivered quality.
” Minimum setup changes-over time for better machine utilization for processing of multiple parts.
” 24-hour working (preferably untended) because of increasing cost of capital investment.
” Built-in better process capability eliminating inspection and to meet demanding accuracy of parts
” Quick-change systems for tooling: tools, jigs and fixtures.
” Optimum automation level in loading/unloading, tool change, and inspection, to eliminate or reduce human influence on efficiency.
” Inventory reduction of tools and other accessories through standardization.
” Total safe operation for men and equipment..
” With improved capability of manufacturing, parts are becoming complex to reduce number of parts in assembly and to ensure built-in quality.
” High speed machining system and bulk machining to produce component from raw material such as billet.
Major objectives for manufacturing engineering today are different. Major emphasis is on low-volume and large-variety, even in high volume production industry to face global competition. Flexibility is also required to use the same facility for the minor or major model changes that come in effective life span of the equipment. Basic work-piece may change in different manners demanding flexibility in its manufacture.
Time cycle over the years have reduced significantly and have made the equipment free to do some extra work to justify the return on investment. Once the equipment is expected to be flexible to handle more types of components, two other factors must also be carefully considered - firstly the increase in investment due to flexibility and then the effectiveness of flexibility. While the increase in investment to ensure flexibility must be the minimum, the effectiveness of flexibility must be real. Production loss for changeover must be minimal. Changeover process should not influence the expected life of the equipment and the quality of output after every change. It has been observed that sometimes the flexible equipment turn out to be the most inflexible one when it is put in actual use, if not properly planned.
In last decade, improvements and innovations in all the areas have been significant. The processing has become faster. The quality is better with gradually narrowing of tolerances over last five decades. Unit cost has been gradually reduced.
- Indra
Category: Manufacturing |
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