What is meant by Machine capability and what
The discrete operation that should be capable of achieving +- 4 standard deviations from xbar within tolerance
What is meant by Process capability and what
Combination of variables EG people, machines, etc.. should achieve +-3 standard deviations within tollerence.
Define what is meant by statistical process control
SPC is an organised sampling technique for taking measurements to detect variability that may result in components being scrapped. For variables samples are collected into subgroups size “n” and charts are produced of the mean and range
)Describe the important features of a digital height gauge and include the range resolution and accuracy
Range: 800mm
Resolution:0.001mm
Accuracy: 0.005mm
Define what is meant by selective assembly. Explain where it is used in ball bearing manufacture and highlight the advantages.
Selective assemly is used to reduce the manufacturing costs & allow wider process tollerence.
Selective assembly is also used to optimise fit between parts
This involves 100 degree C inspection? and the grading of parts
Selective Assembly - Explain where it is used in ball bearing manufacture and highlight the advantages. Use sketches to illustrate your answer.
Select optimum ball DIA d. using selective assembly EG (d+) (d-).
For best fit between ?races? D1 D2
Advantages - optimum fit, reduces noise, increased life (improved quality)
What is meant by the Six Sigma Quality Level
A process with six sigma quality is assumed to produce long term defect levels below 3.4 per million.
What is meant by Cost of Quality?
and describe 5 areas where costs may be incurred for poor quality
The cost as a percentage of sales revenue when operating at different sigma quality levels
- Returned Goods
- rework
- Inspection
- Prevention methods
- Opportunity costs
