Optimizing Design for Additive Manufacturing: The Importance of DfAM for Binder Jet

What Is Design for Additive Manufacturing (DfAM) and why does it matter?

Hybrid manufacturing – CNC machine tools and 3D printing working in tandem – leads to new possibilities in machine shop performance. Contrary to replacing CNC machine tools, it’s beneficial for every metal 3D printer to be supported with a CNC.

Rather than obsoleting CNC machining, 3D printing is a way to free-up capacity for CNCs to do what they do best: precision work. Hybrid machine shops let binder jetting get them to the end result faster; much in the same way a casting requires post processing to remove flash and runners or machine precision tolerances, 3D printing results in a near-net shape part more efficiently. Instead of cutting away what becomes scrap material from a billet of metal larger than the end part, powder is bound together in the shape needed, reducing waste and increasing material use efficiency. After 3D printing, critical surfaces still get machined to ensure tight tolerances. Binder jetting uses only the material needed to build the part, resulting in a greener manufacturing process and increased ROI through raw material efficiency.

Five Key Principles of DfAM for Binder Jet

Binder jetting is known as one of the most versatile additive manufacturing methods because of its material and process flexibility, and effective DfAM for binder jet is key to reaping the benefits of the technology. Here is an overview of five important considerations:

Part Size

While virtually any size part can be made with binder jetting, for metal powder that requires sintering the technology has sweet spots. For its current maturity level, it tends to favor higher volume production, complexity, and parts that are fist-sized or smaller. Binder jetting can enable standard Metal Injection Molding (MIM) MIM-size parts at affordable lower volumes and also enable MIM-style parts at larger sizes, even exceeding 100 grams. Binder jetting is capable of delivering larger complex parts, often with optimization that reduces weight of the overall structure.

Compensating for Shrinkage and Warping

Metal parts produced with binder jet additive manufacturing are sintered after printing in a high-temperature furnace, where the particles fuse together into a final metal object that is dense, accurate, and can be machined. This final sintering step is nothing new in the world of metal manufacturing. In fact, it’s nearly identical to how metal parts have been made with metal powder and binder in the Metal Injection Molding (MIM) or press-and-sinter (PM) markets for more than four decades. Powdered metal parts shrink during the sintering process due to the consolidation of metal particles. Predictive algorithms in Desktop Metal software solutions automatically calculate shrinkage to provide scale up and design adjustments that compensate for sintering.

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