Design Analysis: A Critical Part of the Design Process

Industrial design and product design are often thought of as creative professions that are exclusively motivated by a free and open spirit, focused on developing a revolutionary new product. Although there is some truth in this ideal, there is another essential aspect to design that is often ignored: design analysis.

The reason design analysis is ignored is because it isn’t exciting or emotionally charged. Really good design analysis requires patience, logic, objectivity, extensive technical knowledge, keen observational skills, and methodical procedures. Great designs are never developed from start to finish without numerous revisions and checkpoints throughout the process.

The need to test, verify and revise the evolving design is because what looks great in CAD or on paper often does not translate well into the real world. Well-planned design projects require numerous milestones throughout the development process to verify critical functional and performance features of the product being developed. These functional features can range from user requirements to manufacturing-related parameters to overall performance and reliability.

Post-production is another phase of design during which time designers must be able to effectively perform failure analysis. Although designers try to avoid post-production problems with their designs, every experienced designer has had to deal with a problem associated with a product they designed. Here are some suggestions for effectively dealing with post-production design-related problems.

Use Caution with Analysis: Consider the Big Picture First

First, never make design changes before you have completely identified the source of the problem. If parts don’t fit properly or if parts are breaking unexpectedly, molders will usually suggest changing a dimension or making a design revision to correct the problem. WRONG! Never listen to these people.

Molded plastic parts can twist or shrink in unexpected ways that are difficult to easily observe or measure. This is especially true for large parts with complex surfaces. When these parts are measured the dimensions are often within specifications and the slight twists or surface deviations are imperceptible.

However, when these parts are mated to another piece, one may observe a very irregular wide gap or a gross surface mismatch. It’s during these stressful moments when a molder will suggest the design is flawed and the mold must be modified. If you follow this person’s advice you will quickly slip into a dark hole of no return.

Conversely, you must objectively examine the CAD assembly design and meticulously observe the mating parts based on linear dimensions, flatness and potential areas of distortion that could be contributing to the misalignment. You should also verify the molded parts are identical to the CAD file based on the defined features. The process is painstaking, tedious and time-consuming, but it is required to identify the root cause or causes of the problem. Once the root cause has been identified corrective action can be taken.

Although the previously described scenario is common for plastic parts, surprisingly, many engineers don’t take the time to identify the root cause of a problem and make changes. These changes often require more changes until the design has been so badly altered that the root cause is almost impossible to identify.

When you are faced with everyone offering their advice, take a deep breath, maintain objectivity and analytically process all the facts.

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