In terms of engineering and plastics machining in particular, there are always a few important things to keep in mind regarding tolerances. When a particular part is manufactured, it typically has certain requirements that must be adhered to in order for it to work the way we (and our clients) need it to. If a part is manufactured based on a client’s specifications but certain dimensions or properties are out of tolerance, this ultimately means that it is not going to be usable in terms of what it was originally intended for.

Tolerances in plastics machining can refer to nearly anything – from physical dimensions to measured values like temperature and humidity and more. Think about it a bit like a box that you’re trying to fill before you move from one home to another. If you put too many items that are too heavy in that box, it’s going to collapse as soon as you pick it up – even if the items physically fit inside the box while it was still on the floor.

When you consider that plastics machining parts are used in everything from aerospace to automotive and everything in between, the consequences of getting tolerances wrong are far too great to leave to chance. This is why understanding as much about plastics machining tolerances as possible is so essential.

Factors That Affect Tolerances

One of the most important things to understand is the age-old rule of “the larger the part, the greater the tolerance that will be required). The coefficient of thermal expansion (also referred to as the CTE) is and will always be at play here, and the affects of this simple concept can have big implications on the finished product if they’re not carefully monitored.

Other factors that are known to affect tolerances include the geometry of the part being machined, the specific material that is being used and even the approach to machining that the part goes through in the first place. Thicker parts, for example, are much more likely to maintain their target flatness with the right care and attention-to-detail. Flat parts are pretty difficult to keep “totally” flat, yes – but even issues like bowing can be prevented with special technique and a deep understanding of what factors affect tolerances and how they in turn impact the rest of the goals that you’re trying to accomplish.

All of this is a large part of the reason why we at JMJ Profile, Inc. have dedicated ourselves to a malleable approach to quality precision plastics machining above all else. By that, we’re using the term “malleable” both to describe our own internal process to get you the parts you need when you need them the most AND the unparalleled levels of flexibility and versatility that they in turn provide to you on your own projects. We’ve written in the past about how experimentation is the key to success in that regard – factors like the tolerances of plastics machining are among the many, many reasons why we firmly believe this will always be true.