Jeff

Approaches to Quality Assurance

Inspection Inspection and Quality built

of lots corrective into the

before/after action during process

production production

Acceptance

sampling

Process

control

Continuous

Improvement

The least progressive The most progressive

Inspection

Inspection is an appraisal activity that compares goods or services to a standard. Inspection is a vital, but often unappreciated aspect of quality control. The purpose of inspection is to provide information on the degree to which items conform to a standard. The basic issues are

1. How much to inspect and how often.

2. At what points in the process inspection should occur.

3. Whether to inspect in a centralized or on-site location.

4. Whether to inspect attributes (i.e., count the number of times something occurs) or variables (i.e., measure the value of a characteristic).

Acceptance sampling and process control

Inputs

Transformation

Outputs

Acceptance Process Acceptance

Sampling control Sampling

Where to Inspect in the Process

In manufacturing, some of the typical inspection points are

1. Raw materials and purchased parts. There is little sense in paying for goods that do not meet quality standards and in expending time and effort on material that is bad to begin with.

2. Finished products. Customer satisfaction and the firm’s image are at stake here, and repairing or replacing products in the field is usually much more costly than doing it at the factory.

3. Before a costly operation. The point is to not waste costly labor or machine time on items that are already defective.

4. Before an irreversible process. In many cases, items can be reworked up to a certain point; beyond that point they cannot.

5. Before a covering process. Painting, plating, and assemblies often mask defects.

Process Variability

1. Are the...