Optimizing Design for Direct Digital Manufacturing
Figure 1: Klock Werks Bezel
Figure 2: BMW jig
Figure 3: Injection blow molding in polycarbonate plastic
1. Manufacture end-use, sell-able goods: the manufactured items are the components and sub-assemblies that contribute to the finished product that is sold to customers (Figure 1)
2. Produce end-use items for the manufacturer: rather than making a company's products that are sold to the consumer, additive manufacturing is used in this instance to create devices that aid in the production of sell-able products. Generally, these take the shape of jigs, fixtures, and other assembly aids. (Figure 2)
3. Creating tooling for product creation: whether it is for molding, casting, or forming of products, this application uses additive manufacturing either for the direct production of tooling, or the indirect creation of tooling from a pattern. (Figure 3)
The versatility that is afforded throughout the design and part creation processes with the utilization of DDM is unrivaled by traditional manufacturing methods, making it a popular choice in aerospace, medical, and industrial industries, amongst others. However, to take full advantage of all that DDM has to offer, it is important to consider the differences between the two processes throughout the entire part creation process - beginning with part design.
Recently, a Stratasys customer inquired about using Fortus 3D Production System to manufacture a medical device out of PPSF (polyphenysulfone), with a hollow interior chamber as one single part. The customer’s existing profusion tray design was created for the injection molding process, and included two separate sections that are molded and glued together. This is a time consuming and expensive process that the customer wanted to avoid, due to low volume requirements and occasional design revisions. FDM technology offered the opportunity to manufacture the perfusion tray in low volume at an acceptable cost with the flexibility to make design changes when needed. The current profusion tray design could not be built without supports generated inside the hollow coolant chamber; with no way to remove these supports, this design iteration is clearly not optimal for use with additive manufacturing.
Figure 4: Self-supporting angles
Figure 5: Optimized-design perfusion tray
However, rather that continue to use their traditional methods, a solution was found in another aspect of the process. By working with the original 3D CAD files and revising the geometry, as well as utilizing the self-supporting properties of the FDM process, a design was created that allowed the part to build without interior support. This new optimized design utilized interior angles that would allow the coolant chambers of the part to be built using “self-supporting” angles (Figure 4). In order to build without support, these top surfaces had to be changed so that no interior angle in the chamber would be greater than 45 degrees from the vertical. The 3D CAD file was revised to include this new angled geometry and a STL file was generated. The engineers shared files with the Applications Engineering team at Stratasys, working together to create a workable, one-part design.
Through an optimized design, this medical device company was able to produce an the part without internal supports (Figure 5). FDM technology provided the company the opportunity to manufacture the perfusion tray in low volume quantities at an acceptable cost, with the flexibility to make design changes when needed. The end result is a functional product manufactured in one piece on a Fortus system from PPSF material.
The utilization of self-supporting angles is but one example of how the design process can be optimized for DDM; from altering design to take advantage of the properties FDM's thermoplastic materials provide, to using Polyjet Connex technology to incorporate multiple colours and materials into a single part, almost every aspect of part creation can be leveraged to suit additive manufacturing.
As Canada's leader in additive technologies, Cimetrix has been helping various industries integrate DDM into their workflow for almost 20 years. From design alterations to the post-processing and finishing of parts, we provide customers with industry leading services in order to help you get the most out of additive manufacturing and experience all the advantages DDM has to offer. To find out how, please visit us at www.cimetrixsolutions.com.