Understanding The Evolution Of Tolerances In The Aerospace And Automotive Industries


Times have changed. The same goes for manufactured parts produced by the aerospace and automotive industries. Their complexity grows each year and that is why tolerances that must meet metrology and quality control standards are now increasingly optimized and sophisticated. What’s more, a growing number of clients are requesting their suppliers to ensure their own compliance control aka GD&T is up to required standards. Compliance control was previously a mere input control sample designed to assess a lot’s compliance.

What is Geometric Dimensioning and Tolerancing?

Simply known as GD&T, it is a system for communicating and defining engineering tolerances. It comprises a symbolic language on computer-generated 3D solid models and engineering drawings that clearly describes the actual geometry as well as its allowable variation. Manufacturing staff and relevant equipment will receive vital information on what degree of precision and accuracy is needed on each controllable feature of the work piece. All these events have certainly put a lot of pressure on quality control and metrology teams.

Tolerances are Released to Help Bring Down Production Costs

In an effort to not affect the perceived value and final quality, tolerances are loosened and will have to be offset by more efficient and optimized assembly processes. The current approach is to have extremely tight tolerances to achieve a final product that is problem-free. While this approach works, it tends to produce higher quality products than are actually necessary. Modern approaches called Industry 4.0 take a comprehensive approach to the process. It ensures that the product is produced with just the necessary tolerances, no more, no less.

Tolerances in Aircraft Fuselages Manufacturing are being Tightened

Fuel consumption represents a large portion of airline companies’ operating costs. Fuselage quality directly affects the aforementioned. In order to save a few percentage points on fuel consumption, it is recommended that you stay as close as to the desired plane geometry as possible. In addition, you need to ensure that you achieve that with the most regular possible surfaces.

Tolerances in Car Body Manufacturing are Tighter than Before

The value perceived by the customer can be affected by a factor called assembly quality. Hence, Japanese, North American, and historical European manufacturers utilize this important differentiator to distinguishes themselves from lower-cost brands. This is also one of the ways generalist manufacturers get closer to high quality and luxury standards, and again, stand out from low-cost mediums. This means that complex freeform shapes still need to be controlled, in terms of automotive and aerospace body parts.

Now that GD&T standards are being more widely recognized by the industries. They have begun to appear on the production floor and manufacturers must adapt to this new system for the communication and definition of engineering tolerances. In addition, how the various elements of the part interact, i.e. cutting, surface, roundness, parallelism, etc., must also be controlled.

Consequently, the use of modern metrology equipment that comes with greater portability has become unavoidable. Relevant organizations must have access to different measurement solutions that can be moved to the production floor, reducing the pressure on more accurate equipment. One example is fixed coordinate measuring machines.

by George Chitos

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