Caterpillar cuts rework time with an 3D printed check fixture.

The breather ports on a Caterpillar customer’s engines have to be assembled at a precise angular position so they line up with connecting tubes added at a later assembly stage. However, it’s difficult for assembly technicians to know if the outlets are positioned exactly per blueprint specifications. Angular position is determined by eye and there’s no precise physical reference to work from. As a result, outlet tubes can be mislocated and have to be repositioned later in assembly, adding an hour of rework per engine.

To solve the problem, Caterpillar used a 3D printed fixture that correctly positions the outlet tubes before they are clamped and bolted down. A circular indicator with degree marks is built into the fixture to help the assembler verify the breather port tube is angled properly for alignment with the connecting hardware added later. An advantage of 3D printing this type of check fixture is that it can be easily printed in one piece in a relatively short time with the position marks incorporated during the print operation.

Since adding the fixture into the assembly process, Caterpillar has eliminated mispositioned outlet tubes. Given typical daily production levels, this saves three to five hours of rework each day. It’s a good example of how FDM 3D printed tools and manufacturing aids can be quickly deployed to improve quality and avoid productivity-killing rework.