Archive: Aug 2024

Design for Manufacturing: Surface Flatness, Mating Parts, Wall Thickness and Undercuts

In our day-to-day work at Peerless Precision, we’re constantly seeing new designs for CNC machined parts. And after working on so many of them, we recognize a few common design decisions that can have an unexpected effect on price and lead time. These aren’t design errors, but instead, they’re choices where an alternative decision could save a customer valuable time and money.

This is the essence of “design for manufacturing” (DfM), an approach that aims to identify cost-effective practices for producing parts without compromising on quality or functionality. We always like to ensure customers know that certain features, such as tight tolerances, may increase the cost or time for manufacturing a part. It’s important for us to provide our customers with all the information possible about how different design choices could potentially lower their prices.

These are four of the most common areas where we offer DfM tips to maximize our customer results.

Surface Flatness

We are capable of achieving extremely flat parts at Peerless, but we always try to work with customers to make sure they understand how flatness can impact pricing. Flatness can be difficult to achieve after certain processes like heat-treating or when using strong materials like titanium.

Sometimes we discuss the impact of a certain level of flatness with customers, and they decide the part will be just as functional with a less perfectly flat surface. For instance, one recent part request we received had strict flatness requirements, and we discussed with the customer the effect this would have on pricing and timeline. They decided that the part wouldn’t lose any functionality with a lower degree of flatness.

Mating Parts

Mating parts is a strength of ours at Peerless Precision. After all, it’s how we initially got our foot in the door of this industry 30 years ago in aerospace machining.

However, even our experienced team may encounter challenges when designs lack sufficient clearance between mating parts. The amount of clearance significantly impacts the time and cost of manufacturing, so organizations should ensure that the clearance matches the part’s intended function.

One suggestion in our DfM eBook is to use fractional diameter holes in the corners so the manufacturer can simply drill out and then machine the profile. This isn’t always aesthetically pleasing, but it will decrease the time and cost to manufacture. This may be a good choice for parts that are not visible in the final application.

Wall Thickness

In our eBook, we recommend that “the machined part wall thickness should be greater than .060 inches. If walls are too thin the part may distort and warp, especially if using a plastic material.” That being said, we can go under .060 inches, but it might be difficult.

Recently, we began working on a part that has a titanium shaft welded to a cone. The titanium shaft has a wall thickness of .003 inches and the cone has a wall thickness of .002. We asked our customer if their previous supplier had been able to achieve the wall thickness for the cone. They said that, in fact, the previous supplier could only achieve .003 – but that the part had worked as functioned. This information changed our approach to the part, and any sort of context or background information a customer can give us about a part can often be very helpful in the manufacturing process.

Undercuts

In our DfM guide, we note that “undercuts should be avoided as they add cost and possibly lead time to the part.” However, some parts do require undercuts. In that case, it’s just important that a customer understands this feature will affect price. If a customer wants a part made without undercuts, we are happy to discuss how a new design could potentially avoid these features.

These are just a few tips, but at Peerless Precision, we have decades of advice and expertise we’d love to share with you. Request a quote today to discover how our expert CNC machining services and extensive knowledge can benefit your next project!