Revisions and Retracing

The Engineering Change Process

Depending on the size of a business, the engineering change process involves many facets. Contrary to conventional wisdom, the change process does not always originate in the engineering function. For example, marketing may deem it appropriate to initiate changes in a product because of market conditions or cost; however, engineering is the conduit through which the changes are made. In the aggregate and aside from the marketing and financial considerations, changes usually originate within the engineering or drafting function.

The quantity of paperwork required to process an engineering change is directly proportional to the complexity of the product, the formality required to introduce the change, and the size of the organization.

Revision of Engineering Drawings

This section defines drawing practices for revising engineering drawings and associated parts lists. Practices for identifying and recording revisions are also provided.

The practice of revising engineering drawings and associated lists is one of the most important links in the engineering documentation structure because of the far-reaching effects of the action. Revisions may trigger substantial paperwork crossing all functions of a business; therefore, the need for accuracy and completeness in the revision action should not be underestimated.

The principles covered in this section apply equally to computer- aided documents and those prepared manually. These principles encompass specific practices for revising, retracing, identifying, and recording revisions to engineering drawings and associated lists and the relationships among the revision authorization documents.

Reference Documents

    ANSI/ASME Y14.34M 1996, Associated Lists.
    ANSI/ASME Y14.35M 1997, Revision of Engineering Drawings and Associated Documents.
    ANSI/ASME Y14.24M 1989, Types and Applications of Engineering Drawings.
    ANSI/ASME Y14.5M 1994, Dimensioning and Tolerancing.
    ANSI/ASME Y14.100M 1998, Engineering Drawing Practices (replaces DOD MIL SPEC 100).

Redrawing and Retracing Considerations

As the design of a product matures, the related drawings are frequently subject to extensive revision because of design refinements and general handling of manually drawn tracings. In turn, this results in general deterioration of the quality and adversely affects the legibility and general meaning of the data on the copies. Thus, it is very important that original tracings be clean and uncluttered. This section provides guidelines for the maintenance of high-quality drawings that are subject to frequent change.

Change - Document Guidelines

Because each company is unique in its own operation, products, and revision controls, a standard change-document format is not practical. The use of one change document may suffice in some companies, while in others many documents are needed to control changes.

Design Quality and Checking Practices

Design quality is conceived and built into the product long before it is manufactured. It is not a characteristic that can be added to the product after manufacture; it must be a part of the total design iteration at the outset of the design.