An Easy Way to Add Inserts into FDM 3D Printed Parts

At Stratasys Direct Manufacturing, the build volume of a 3D printer doesn’t scale down the size possibilities of parts. Our expert assemblers have precise methods curated over decades to make multiple components of a part that seamlessly align for a large assembly. 

Some of those assembly methods include fasteners like nuts, bolts and threaded rods. It’s also common to attach fasteners to parts using a process like heat staking. Assembled Fused Deposition Modeling (FDM) components can benefit from hardware added in the middle of the build.

FDM machines can be paused in the middle of the build process, allowing technicians to add hardware into a specific layer or a pre-designed cavity, before resuming the build. To use mid-build inserts, a technician pauses the FDM machine and applies a clear coat to the surface of the insert, creating a tacky surface for the thermoplastic to adhere to. FDM is the only 3D printing process that allows for the adding of inserts directly into the in-build part. 


fdm 3d printing

There are significant benefits to utilize mid-build inserts in FDM assembly components, including:

Elimination of Secondary Operations

When you are building multiple parts for an assembly, adding hardware in the middle of the build allows the components to be put together as soon as they come off of the machine. This eliminates any secondary operations that can add to turn-around times. 

Increase of Part Strength

FDM parts are built with engineering-grade thermoplastics, but sometimes applications require additional durability and strength. Hardware like metal rods can be inserted into parts to reinforce the thermoplastic material and increase overall part strength.

Addition of Large Hardware

For some automotive and aerospace applications, large washers, nuts and other hardware are required for assembly. Due to the size, these can often be difficult to heat stake into a component, the more traditional approach. By firmly embedding the large hardware inside the thermoplastic mid-build, the specialized inserts have the support needed to hold up in a more robust application.

Mid-build inserts for FDM assemblies require some planning. Elements to consider include:

  • Addition of a Cavity to the Design - When building a CAD file, designers should create cavities within the part to account for any inserts that will be added during the build process.
  • Orientation on the X/Y Plane - FDM 3D printers can only be paused in the Z orientation of the build. The build orientation of a part needs to be on the X/Y plane in order to place the inserts in the cavity and ensure it is fully covered in material. When placing an online order or speaking with a Stratasys Direct Project Engineer, be sure to specify the X/Y orientation.
  • The Right Materials - The higher build temperatures of certain FDM materials like as ULTEM™ 1010 resin and PPSF will burn off the clear coat applied to an insert needed for adhesion. However, the process can be used for these materials for smaller inserts. A smaller cavity can be bridged by layers of the thermoplastic without having to fully adhere to the insert. Discussing how and where the part will be used with a Stratasys Direct Manufacturing engineer will help you determine the appropriate material for your designs.

The professional assembly services at Stratasys Direct can enhance what a designer, engineer and product team can do with 3D printing. FDM mid-build inserts streamline and improve upon the assembly process and offer streamlined possibilities for new parts.

Fused Deposition Modeling Resources


3D Printing Puts Fixtures into Gear

Automotive parts supplier gets up to speed on FDM’s capabilities for fixtures

Read Case Study

Bringing Downtown Detroit to Life

The District Detroit Project Uses FDM to Showcase a New Motor City

The District Detroit Project Uses FDM to Showcase a New Motor City

Read Case Study
jigs & fixtures

Jigs & Fixtures for the Production Floor

Open up new possibilities for manufacturing-floor productivity.

Download White Paper

How it Works: Fused Deposition Modeling

“It can create parts and geometries that you can’t do in injection molding.”

ULTEM™ is a registered trademark of SABIC or its affiliates or subsidiaries.