Tolerances are an important aspect of how our industry communicates about designs. They are a way of indicating what requirements must be satisfied in order for a part or product to function as intended. However, tolerances that are either over-engineered or under-engineered can result in parts and products that cost more and take longer to make than they need to.
Over-engineered Tolerances
It can be tempting to put tight tolerances on every facet of a design. After all, who wouldn’t want every dimension of a part guaranteed to be accurate to within thousandths of an inch?
The problem with this approach is that it doesn’t always take into account what would be required to fabricate a part to those tolerances, or if it’s even possible to do so. Designs that over-engineer tolerances tend to result in high prices for those parts because extraordinary ingenuity must be applied to achieve those tolerances.
There are also limitations in the physical world to consider, such as the tolerances for raw materials like metal sheets. For example, if you have a sheet of 14 gauge aluminum the stated thickness is .0641”. However, it’s not uncommon for an actual sheet of 14 gauge aluminum to measure .0640” thick, a difference of one-thousandth of an inch. If you’re working with a tight tolerance of just a few thousandths, the tolerance of the raw material could represent a significant fraction of the total allowable variability in the finished product.
Under-engineered Tolerances
On the opposite side of the coin, sometimes it can be tempting not to put tolerances on a design at all.
The problem with this approach is that there are almost always requirements that must be satisfied by a design, and if they are not called out in the form of tolerances it can result in lots of back and forth during the quoting and production stages.
Context and Collaboration are Key
We’ve seen what can happen when you over-engineer or under-engineer the tolerances on a design. What, then, is the right way to go about assigning tolerances?
Identify Design Requirements
The most important first step is to identify what design elements in your project are truly requirements. Which aspects of the design must meet certain criteria in order for the part or product to function successfully?
Share Design Intent
The next step is to share your design intent with us when requesting a quote. At Ameritex, we offer more than just metal fabrication services. We partner with our customers to help them create designs that meet all of their requirements while also optimizing for manufacturability. This leads to parts that can be produced more quickly and at lower cost, saving our customers time and money. The more you tell us about your goals, the better we can serve you.
Communication is Key
It is important to keep the dialog open after you receive our quote. If the price comes in higher than expected, let us know – there may be adjustments we can make to the design to bring the price down.
If you are interested in working with one of our metal fabrication experts to optimize your design for manufacturability, request a quote today! We are more than just a supplier to our customers. We are a partner, utilizing our expertise in all aspects of custom metal fabrication to guide our customers through every step of the process from quoting through to receiving finished parts. Reach out today to experience the difference of working with Ameritex!
