Additive Manufacturing for Fixtures — Perception Engineering

If you have ever undergone an assembly process, then you know how essential a fixture can be. A fixture allows you to accurately position various bodies into place and apply the necessary forces to prevent any movement while securing into place with adhesive, welds, etc. This results in the final product to be as accurate to the design as possible. However, there are a few concerns with setting up fixtures; the main ones being feasibility and cost.

Depending on the complexity of the assembly, it may be difficult to set up a proper fixture with standard parts. These fixtures can be set up on a modular table. This allows you to attach risers, clamps, brackets, and other standard parts in a variety of positions and orientations best suited to position your parts.

As the complexity (i.e. higher number of parts, or complex compound angles) of the assembly increases, so does the difficulty in achieving an effective fixture. Another issue with the complexity that can be encountered is the complexity of positioning. If your assembly includes organic geometry or parts that need to be very precisely positioned, it is very difficult to manufacture a fixture with standard parts that will achieve this.

Luckily, additive manufacturing can help resolve this issue. Brackets can be built directly off the 3D CAD model of your design and printed using the proper 3D printing process. This ensures it will position your part just as intended and hold it firmly in place, within the tolerance of the fixtures, while it is secured.

As there is a range of 3D printing processes, each with their own tolerances, this can vary depending on what application is right for you. With traditional FDM printers, tolerances can be achieved as low as ±0.2mm but are more often found to be around ±0.5mm, all while reducing the chance for human error.

Traditional brackets are likely to be milled from aluminum, as this is quick to machine, while generally having enough strength for the purpose. With new innovations in the material science of 3D printed materials, you do not have to sacrifice any of that strength when switching to additive manufacturing. In fact, you can end up with stronger parts in less time. Markforged, a 3D printing company, offers a line of continuous fiber composites for FDM printers, such as carbon fiber, fiberglass, or Kevlar infused fibers. By using carbon fiber infused fiber printing for creating your fixture components you end up with parts that have up to 20% higher yield strength than those made of aluminum, with less weight and lower lead times. The increased stiffness offers lower deflections when placing your assembly components, therefore resulting in a more accurate final product. Of course, if high stiffness is not of major concern, there is a wide range of traditional materials that can be printed on almost any desktop 3D printer such as PLA or ABS which could cut costs even more. Additive manufacturing offers a wide range of materials and likely has one to fit your needs.

As mentioned, the cost is also often another factor in setting up a proper fixture. The cost goes hand in hand with feasibility. As expected, as the complexity increases, the cost will likely increase as well. Once an assembly reaches a certain level of complexity, it often requires custom manufactured parts. Traditionally this has been achieved with the use of subtractive manufacturing methods such as milling. The more precise a fixture component needed, the more expensive it will be. If you have ever purchased precision milled components, then you know how quickly this can become very costly. This can be mitigated with the use of additive manufacturing. 3D printing the complex fixture components gives you the accuracy needed at a fraction of the cost. Savings of up to 94% have been seen for certain applications when factoring in the material and labor costs of custom components. For the next blog in this series, we will take a more in-depth look at a use case and show the cost analysis for the savings achieved by utilizing additive manufacturing.

While additive manufacturing is a great tool for the purpose of assembly fixtures, it is not the right choice for everyone. This is especially true if the fixtures are being created in a high volume. If you are creating a high-volume assembly line with large quantities of each fixture, then traditional manufacturing methods will likely be better suited for your purpose.

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