Working as an R&D or product development engineer, there is an almost daily need to rapid prototype designs in order to meet accelerated project demands. Accelerated project demands are partly driven by the evolution and availability of additive manufacturing and on-demand manufacturing services now available to engineers, which have shortened development cycles. When allotted, only a few days’ time following a roadmap for rapid design will yield successful results while limiting heart attacks.
Engineers who follow the subsequent roadmap for rapid prototype design will be able to keep their projects on track from concept through to prototype.
Starting Line: Clearly Defined Expectations
Successfully rapid prototyping a design starts with having clearly defined expectations. Easier said than done, as always, but getting just a few sentences on paper or in an email to summarize the scope of work will keep the design and evaluation of the prototype focused and accurate.
Note: An example of a clearly defined expectation is articulating whether the design/prototype needs to convey function over form or vice versa.
Turn 1: Start with Sketches, Not CAD
Starting a rapid prototype design with hand-drawn sketches is faster and allows more room for creativity than modeling in CAD. It helps to ignore limitations of manufacturability while sketching in order to allow room for innovative and creative solutions, in addition to being a quicker mode for this task.
Tip: Using the sketches, consult with your peers for feedback or insight. A solution could be sitting on the desk next to you.
Turn 2: Simple Prototype First
As certain as death and taxes, the rapid prototype design will not work as expected the first time. First, make an ultrasimple prototype that evaluates the major functions of the design. If done immediately after sketching and prior to any CAD, poor design ideas will be instantly flushed out and this will preserve time for the iteration process.
Note: An example of a Simple Prototype is a prototype made of parts pillaged from existing products along with a bit of junkyard ingenuity.
Turn 3: LeanCAD
LeanCAD is how I refer to the methodology of CAD necessary for this stage of the process; simple modeling to meet the intended outcome. A LeanCAD engineer will not get stuck in the weeds finely crafting details and features when creating models for a rapid prototype design. A LeanCAD engineer will keep in mind the prototype manufacturing processes to be used and the limitations of the design and will leave room within the design for modifications to parts to be made on the fly as-needed after manufacturing or during evaluation. A LeanCAD engineer will not spend time on parts of the model that are unnecessary for this phase of work.
Note: An example of LeanCAD would be oversizing clearance holes for a part manufactured using an SLA process to account for shrinkage during manufacturing.
Finish Line: Established Relationships Get Good Parts Fast
When it comes time to manufacture parts for a rapid prototype design, it’s best to already have established relationships in place. It’s unlikely that a cold call to a new resource or vendor will yield fast, quality results. Established relationships also help when it comes to selecting materials and processes since there will be confidence in communication enabling fast execution.
Tip: Vendors with whom you’ve already established relationships will be willing execute prior to a PO or payment to expedite delivery of parts.
-Andrew Calabrese, Sr. Mechanical Engineer