Beginning Your AM Journey: One Part to Begin the Path
Identifying the right part to begin your additive manufacturing path can demonstrate and validate the AM workflow, provide a benchmark for future work and more.
I can’t believe I am writing this column given what I wrote last month. In case you missed it, I argued that reproducing an existing part “as is” with additive manufacturing (AM) generates very little upside. Rather, it will invariably cost more to get the same performance out of AM, which is a tough sell to any boss. Granted, such a process substitution, or direct part substitution as it is often called in the AM community, may have a speed advantage. However, if the speed advantage does not convert into a lead-time advantage, then the schedule benefit is moot since the process is already designed, analyzed, tested and producing the part. There is no upside to shortening the product-development cycle for a part that already exists. Nonetheless, this is often where established firms start their AM journey, and I want to provide some guidance to those in the same position.
These are the most frequently used criteria for picking parts for AM based on a recent review of a dozen AM part filtering/screening methods. Photo Credit: Tim Simpson and Jen Bracken, Penn State
Based on a recent review of a dozen methods for identifying AM part candidates, the most common criterion that makes it challenging to fabricate via conventional means is part complexity. This should come as no surprise as complex molds and tooling, multiple setups and fixtures, complicated cores and patterns, etc. drive up costs and make conventionally produced parts expensive. Given AM’s potential to make complex features means that this is a good place to start looking for a part candidate, but it does not guarantee success. Complex geometries often translate into more support structures and postprocessing when working with metal AM processes, and this drives up costs.
While complexity does not guarantee AM part candidacy, I will say that the converse is always true. If the part is simple, easy to produce by other means, requires few setups, and does not need any specialized tooling or fixturing, then it is clearly not a good part for AM due to cost. Granted, cost is not the only driver to consider, and sometimes learning or validating the AM workflow is worth the investment.
The next thing to keep in mind is that AM remains limited in terms of both the commercially available materials that can be processed and the size of the parts that can be made. So, material and part size are the second two most frequently used criteria when picking parts for AM.
While countless new materials are in development, there are still only about 50 polymers and roughly 20 metallic alloys that are readily available for AM. Though manufacturers
Similar to limited materials, the build envelope — the volume that can be 3D printed — is still constrained to roughly 1 cubic foot on the vast majority of laser powder fusion systems. Companies like 3D Systems, Additive Industries, Big Metal Additive, GE Additive, Relativity Space, SLM Solutions and Velo3D are pushing the build envelope for metal AM technologies. On the polymer side, Cincinnati’s Big Area Additive Manufacturing (BAAM) system still leads the size race with its 20- × 7.5- × 6-foot build volume and 80 lb/hr. deposition rate.
So if a part is relatively complex, fits on an AM machine and is made from an available material, could it launch an AM journey?
Maybe, but the next set of criteria that are most frequently used for screening parts for AM must be considered. These include the cost of AM, the build speed, the need for supports and trapped powder. Finally, one must factor in part consolidation and topology optimization, postprocessing, tolerances and customization.
That rounds out the top 10 criteria for picking an AM part, but again, this does not guarantee success. Only four of these criteria (feature complexity, part consolidation, topology optimization and customization) fall into the value-add category when designing for AM. However, if making the part “as is” is a constraint, then this value cannot be captured.
Luckily, there are a few situations in which this can be an advantage. In cases like these, finding a reasonable “pathfinder” part can still be beneficial. It can help demonstrate or validate the AM workflow internally or with external suppliers, provide a benchmark or baseline for future redesign efforts, and help “de-risk” the technology by gaining the necessary insight into an AM process. More importantly, it can help people overcome their fears (for example, are AM parts strong enough?) and get excited about AM technology, setting up companies to do more with their next AM parts.
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