Learning Activity Part A
The Need For Capability Studies
1. The aim of SPC is to help bring about continuous improvement to all processes, helping achieve customer satisfaction.
2. To assure continued customer satisfaction, strict conformance to all customer requirements must be a goal of a company.
3. It is more economical to produce to requirements than to sort and rework in order to meet requirements.
4. Consistent performance requires consistent machine and process capability.
5. Process capability = machine capability (inherent variability) + process control.
6. To measure this conformance, capability studies should be performed.
Capability
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Definition: Capability is the inherent reproducibility of a process. In statistical terms, a process's capability falls within a range of 6s. This 6 standard-deviation spread will include 99.7% of the product being created by the process. Note the capability does not indicate whether the process is producing what your customers want. It is only indicating what the process is capable of doing. |
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Chef Molly is considering adopting a specification of 0.xxx +/- 0.005" for dry penne pasta diameters that she chooses to purchase. Your team can recommend a change to the designated process average based on additional sample data. Molly has stated that the tolerance band is not negotiable.
If you are comfortable with your previous measurement analysis accomplished in the previous activities then determine the % out of tolerance for each of the two pasta brands, and calculate the Ppk, PI, and PR for the two brands.