Metal AM operations have been forced to accommodate legacy materials due to the number of resources needed to design, manufacture, and validate new material.
FREMONT, CA: The products people use every day comprise thousands of metals, each selected for their balance of cost, manufacturability, and performance. All traditional metal manufacturing processes, from casting to stamping, are limited in the alloys they can manufacture. Additive manufacturing (AM) is no different. Each metal AM operation has distinct sets of materials with which it is compatible, and this decides the uses that are viable for each process. Materials are chosen early in the product development process. The compatibility of these materials with manufacturing means is essential to choosing a viable material and process combination. Successfully deploying metal AM requires an understanding of which operations and metals are compatible, today and in the future.
Powder and wire are the first feedstocks for most metal AM operations. The wire is created by drawing a metal rod through a die, an activity that is compatible with most metals. The wire is commercially available in an extensive range of metals. Powder-based metal AM operations often have stringent needs on the powder’s size and shape. Due to these needs, metal AM powders are usually produced through slow, expensive atomization processes, limiting the supply and range of metals produced.
Metal AM technologies use different processing conditions. These include governing the movement of material and power and the dynamics of melting and solidification. The common metal AM process hurdle is the quick melting and cooling cycles, creating large temperature gradients. When materials heat and cool, they widen and shrink, generating residual stresses that can cause metals to warp and crack. This challenge exists in welding. The weld-ability of material often forecasts whether a metal is compatible with AM processes. The exceptions to this are binder jetting, where the part is sintered in one post-processing step, and cold spray, which is a low-temperature, steady-state.