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Supercritical fluid cleaning - McHardy J.

McHardy J., Sawan P.S. Supercritical fluid cleaning - Noyes publications, 1998. - 304 p.
Download (direct link): spercrificalfluidcleaning1998.pdf
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11. Feedback. A feedback loop needs to be established that conveys information regarding the performance of, and problems associated with various parts back to their original designers. For example, every time a part fails to meet cleanliness requirements, and it is determined that nothing has gone haywire in either the vendor or the in-house cleaning systems, the responsible design/development engineers need to be made aware of the incident, since they must share (to varying extents) in the responsibility for the failure. Investigations of line-rejects and line-down situations involving contamination-related causes should be conducted by teams in which the part-designer is integral. The design group should have access to, and be
familiar with, parts cleaning data, problems and history during the life of every precision assembly product.
This list is by no means exhaustive, nor is it meant to be. Rather, it is designed to create a mindset among design/development engineers that cleanability, just like manufacturability and ease of assembly, is a key price-performance issue that needs to be factored in at the outset. In the highly competitive microelectronics marketplace, effective contamination control, when properly integrated with product development, may turn out to be a big advantage. This concept has more recently been discussed in more detail in Ref. 3.
References (for Appendix 1)
1. Bancroft, . E., Introduction to Design for Manufacturability, Internal Report, CIM Technology Center, IBM, Boca Raton, FL, (March 13,1989)
2. Nagarajan,R., Surface Properties and Cleanability: A Rational Correlation, J. IES, 33(l):26-33 (Jan./Feb. 1990)
3. Sipitkowski, J. ., Design for Cleanability: Part Geometry and Surface Finish, Precision Cleaning, l(l):55-57 (Nov./Dec. 1993)
APPENDIX 2: VENDOR PROCESS CONTAMINATION CHECKLIST
A2.1 Receiving/Inspection (R/I) at the Vendor
Are all incoming materials raw (stock) materials?
YES_____ NO_______
Are some of the incoming materials parts supplied by a secondary vendor that will be assembled at the primary vendor?
YES_____ NO_______
Do stock materials receive at least a cursory visual inspection for gross contamination?
YES NO
How is the quality of incoming stock controlled?
If some parts are received for assembly, do the parts have customer cleanliness specs on them?
YES______ NO_________ N/A
If they do, are they being final inspected at the secondary vendor?
YES______ NO_________ N/A________
If they do, are they being R/Id at the primary vendor for cleanliness?
YES______ NO_________ N/A________
Does the secondary vendor have a black box operation
in his process?
YES______ NO_________ N/A
Is inventory managed properly, on a first-in first-out (FIFO) basis?
YES NO
A2.2 Manufacturing
Is the manufacturing process fully documented with the customer?
YES_____ NO_______
Briefly outline/sketch the steps in the manufacturing process.
How many parts are produced per day?
Is continuous flow manufacturing (CFM) being practiced?
YES_____ NO_______
On average, how long does the part wait between successive operations?
MINUTES HOURS DAYS
Are products for other customers being manufactured in the same area?
YES_____ NO________
If so, is there any chance of cross contamination?
YES_____ NO________ N/A
Is machining debris being effectively (across all size ranges) removed between stages?
YES_____ NO________ N/A
If so, state how:
Are the intermediate cleaners dip/rinse tanks or spray units?
STATIC TANKS__________SPRAY CLEANERS____________N/A_______
If dip type, how often is the cleaning fluid replaced?
N/A ONCE A DAY TWICE A DAY OTHER (Explain)___________________________________________
Has the nature of the cutting tool (hard/soft, sharp/dull) been correlated to the amount of machining chips/fines generated?
YES_____ NO________ N/A________
Have tool-bit changes been looked at as a means to reduce machining debris generation?
YES_____ NO________ N/A________
During machining, are the parts spray cooled or flood cooled?
SPRAY FLOOD______________ N/A______
Are all the coolants being used compatible with the downstream cleaning process? In other words, if the cleaner is water based, are all coolants and other process fluids water soluble?
YES NO N/A
If oil-base coolants or lubricants are in use, has the vendor explored the use of water-soluble counterparts?
YES______ NO________ N/A_______
Are Manufacturers Safety Data Sheets (MSDS) for all the chemicals used in the manufacturing process documented with the customer?
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