Additive Manufacturing Design Case for Optimized Production

Etteplan was asked to redesign the 2-to-1 dust extraction channel for a customer’s robotic sander for additive manufacturing. The existing traditionally manufactured component suffered from high costs, was not aesthetically pleasing, had a long logistics chain, and too large of a footprint which caused problems in the assembly line. The customer hoped for a new solution that would be optimized for production by LPBF in aluminum or another metal, and would also be significantly lighter than the original, produced at lower cost, and have improved airflow characteristics.

Design for additive manufacturing in Etteplan is conducted by carefully selected multi-disciplinary teams that use a simulation-driven design approach. By choosing the right experts for every project, we are able to tackle even the most challenging engineering or manufacturing problems. Our experience has led to efficient workflows that guarantee fast results. 

Etteplan assembled a team that included experts in AM production, AM design, and print process simulation. Both Etteplan’s own additive manufacturing production cost estimation tool and AM process simulation software were utilized throughout the design process.

A first AM design iteration of the extraction channel design saw smoothing of the internal air channels and removal of excess material. At this point the process simulation software was used to conduct an orientation optimization whereby the effect of print orientation on build time, support volume, needed post-processing effort and predicted deformation/distortion levels could be analyzed. It was found that two orientations of the extraction channel produced comparable and preferred results in terms of support volume, post-processing and deformations. These orientations resulted in the longest print times for the manufacture of a single component, but they took a minimal area reservation on the build plate – meaning that when the build plate was fully nested with these components, the per-component print time is actually lower than other orientation options.

Additional modifications were made to the design to improve printability in the preferred orientations and to eliminate the need for support structures in regions that would be visible to the end-user after assembly. Print process simulations of the extraction channel in the chosen orientations was used in order to determine where support structures would be required, to ensure that print-direction distortions would not cause collision with the recoater during manufacture, and to check that the final distortion levels of the component were within reason. 

The Etteplan AM cost estimation tool was also utilized during this stage to estimate and compare the costs of various design options with the original traditionally manufactured part. It was found that for the amount of material and print time needed, it was too expensive to additively manufacture a single part.  However, printing 11 parts at once was determined to be the cross-over point whereby the traditionally and additively manufactured parts would cost approximately the same amount.

Further design changes were made so that the number of nested parts produced in a single build were maximized by allowing the parts to be stacked 4-high in the print direction. This meant that a total of 120 pieces could be printed in one job. Process simulation was again used to estimate support structures needed and to simulate the print process for a stack of four extraction channels.

By modifying the extraction channel design to allow stacking in the print-direction and maximizing the number of parts that could be printed in a single build job, the cost of manufacturing a single piece was reduced by 40% compared to the traditionally manufactured component. Further savings can be seen due to the creation of a more agile supply chain and the ability to produce the parts locally on demand and with variable batch sizes. 

The new extractor channel design also featured a number of benefits beyond cost reduction: 

Component codes embedded on the surface

As the dust extraction channels are not significant load-bearing structures, fully dense material with best mechanical properties is not a requirement of the end-product.  Therefore this is a particularly good case where a “good enough” approach to AM process parameter selection should be considered.  By allowing certain regions of the end component to be slightly more porous, significant print time reductions (and therefore cost savings) can be achieved.  For the 4-stack extraction channel design, Etteplan worked with SLM Solutions to optimize the process parameters for speed in the regions where the part is not visible (threaded inlets/outlets) while assigning the standard high quality process parameter set to the rest of the part.  In addition, support structures were optimized to minimize material usage and to make powder removal easier.  With these efforts, the print time of the full build was reduced by 25%. 

Etteplan’s final design of the robotic sander extraction channel met and exceeded all of the customer’s initial AM design objectives. This was made possible by close collaboration and good communication between the customer, Etteplan, SLM Solutions and the service bureau where the parts were produced (3DStep).

It also depended on the combined expertise of the assembled project team who were able to harness the design freedoms of AM and had a strong understanding of the manufacturing process to produce a high-quality product at low cost. Decision-making during the design process was significantly and positively influenced by the use of Etteplan’s AM cost estimation calculator and AM process simulation tools.  Close cooperation with SLM Solutions brought additional cost savings through process parameter optimization.