Threading in 3D Printing: Heat Set and Press Fit Inserts, Tapping

SLS and MJF Parts with Heat-Set Inserts 

Nylon parts that are printed using the selective laser sintering (SLS) or Multi Jet Fusion (MJF) processes can leverage standard sizes of brass heat-set inserts. Why brass? Brass is a soft metal with low annealing temperatures. Before brass inserts are seated into holes, they are quickly heated with a soldering iron. This deforms the nylon allowing it to flow and fill voids around the insert, providing a robust grip around the insert after cooling. Using a brass heat-set insert in your design can also help ensure durability. If you need a heat-set insert that is different from brass, inserts made of aluminum or stainless steel are also an option.

Heat-set Insert Strength in SLS and MJF Parts 

We’ve done some internal tensile strength testing on heat-set inserts installed in nylons, and here’s what you can expect. While a lot of variables come into play, larger and longer inserts that carry greater surface area are stronger than smaller ones. Our testing suggests maximum loads ranging from roughly 100 pounds for very small inserts to, in some cases, more than 700 pounds for our largest inserts. That gives you some sense of limitations, but we recommend testing functionality for your specific application, especially if your part will see sudden, repeated, and/or non-uniform loads. It’s also important to know that longer/taller inserts of equivalent thread size are stronger than shorter inserts. The amount of added strength varies by insert size, but our testing indicates that tall inserts add approximately 30% tensile strength when compared to shorter inserts. 

SLA Parts with Press Fit Inserts

The style of insert differs for parts that are printed using the stereolithography (SLA) process. In this case, standard press fit inserts are used. They don’t require heating to set. Instead, these press fit inserts are reinforced with epoxy for additional strength and security. 

Tapping SLA, SLS, MJF Parts

Tapping holes into 3D-printed plastics is less common than assembling inserts. In your case, though, tapping might be preferred over inserts if keeping consistent aesthetics is critical or if metallic properties are not desired. We stock standard tap sizes, but if there is something you need, just ask. Here is a list of our commonly stocked heat-set inserts, press fit inserts, and taps. We can work with you to ensure proper depth is chosen.

Advantages of Chasing or Tapping for Metal Parts

Designing for Tapping and Inserts in Metal 3D-Printed Parts  

When you get your parts quoted, it’s important to provide all the necessary thread information on the technical drawings. We can review any technical drawings for quote that clearly indicate thread size, pitch, class of fit, and position requirement.

Special Request Inserts and More

So, that’s an overview of how we typically accommodate 3D printing customers. That said, if you’ve got an out of the box design request, don’t shy away from asking us. You can always ship us the inserts you would like us to use, or we can order them for you. We can even source larger inserts for larger parts. Need dowel pins assembled? We have you covered. Just ask. We always review your part with your design requirements in mind. And don’t forget that our applications engineers are here to help guide you through lead time, cost analysis, and design goals when it comes to threading and inserts in 3D-printed parts.