SECTION 1.7
Design Review

Design review is a technique for evaluating a proposed design to assure that the design (1) will perform successfully during use, (2) can be manufactured at low cost, and (3) is suitable for prompt, low-cost maintenance.

The concept of design review is not a new one. However, in the past the term has referred to an informal evaluation of the design. New products often require a more formal program. A formal design review recognizes that many individuals involved in the design phase do not have specialized knowledge in reliability, maintainability, safety, producibility, and the other parameters that are important in achieving an optimum design. The design review aims to provide such knowledge.

SECTION 1.7.1
Design review tools

The design review process can be aided by using some of the following tools:

1. Seriousness classification of characteristics. Such classification is typically divided into three or four categories, e.g., critical, significant, secondary, incidental. Availability of such a classification simplifies the job of identifying the vital few tolerances. (For elaboration, see Section 1.8.)
2. Studies of process capability. The accumulated process capability studies can be organized into tables that show, for the principal processes, their inherent uniformity. These tables greatly simplify the job of predicting whether those processes can hold the proposed tolerances.
3. Charts of cost precision. Data showing the costs of performing operations at various levels of precision is beneficial. It is possible to organize the data in ways which show the correlation between precision and cost. Such relationships are of obvious value.

SECTION 1.7.2
The concept of design review

The design review is based on the following concepts:

1. Design reviews are mandatory, because of upper-management policy declaration, and by customer demand.
2. The design review is conducted by a team consisting mainly of specialists who are not necessarily associated with the development of the design. These specialists must be experienced and bring with them the reputation of being objective. The combination of competence, experience, and objectivity is essential to prevent the design review program from deteriorating.
3. Design reviews cover all quality-related parameters and others as well. The parameters include reliability, maintainability, safety, producibility, weight, packaging, appearance, cost, etc.
4. As much as possible, design reviews are made to defined criteria. Such criteria include customer requirements, internal goals, experience with previous products, etc.

SECTION 1.7.4
Engineering specifications

A detailed design review and understanding of the controlling specifications as supplied by the customer will help the design engineer identify the functional and durability requirements of the tool or assembly which the customer requires. In some cases, acceptance criteria are called out on the engineering specification (usually a blue print of an existing design) provided by the customer. In other cases, all that is provided is a part print, and design engineering must rely on prior experience, Design FMEAs, or Design of Experiments to arrive at and determine which characteristics will affect or control the results that assure meeting function and durability requirements after the product is designed.


SECTION 1.7.5
Material specifications

In addition to drawings and performance specifications, material specifications should be reviewed for significant characteristics relating to properties, performance, handling, and storage requirements. These characteristics should also be included in the control plan.


SECTION 1.7.6
Tolerance review

In tolerance review, as in the complete design review, there are human problems as well as technological problems. A major human problem is the impact of the concept of design review on the traditional "monopoly" of the designers. Historically, they consulted manufacturing people only as they felt the need--the choice was still the designers. Under the new concept of mandatory design review the choice is made for the designers--there will be design review and you will participate. The benefits will only be realized when this "cultural resistance" has been broken.