RapidSteel Part Accuracy 133

In order to assess the effect of various furnace processing parameters on RapidSteel part accuracy, a series of experiments were performed on linear dimensional changes during processing of RapidSteel 2.0 and LaserForm ST-100. An understanding of these dimensional changes is critical for building parts and tools which are capable of being used in high tolerance applications and for finish machining of near-net shapes to high tolerances. A unique part was designed for this study and is shown as Figure 1. This part has both internal and external measurable dimensions in the x, y and z axes. The smallest dimension in each direction is 0.3 inches and the largest dimension is 3.0 inches. This provides an order of magnitude difference between the smallest and largest dimensions.RapidSteel 2.0 (RS2) is a commercially available metal material from DTM Corporation. It is made by Selective Laser Sintering of stainless steel 316 powders with polymer binders followed by a binder burnout and sintering furnace run, and a second infiltration furnace run where a 90% Cu, 10% Sn bronze is infiltrated into the porous stainless steel structure. LaserForm ST-100 (ST-100) is the latest version of RapidSteel and is a stainless steel 420 material that is sintered and infiltrated in one furnace run. The significant difference between RS2 and ST-100 is that the ST-100 has a broader particle size range, with fine particles not being screened out. These fine particles allow the ST-100 material to be sintered at a lower temperature than the RS2 powder, which makes possible the single furnace run for sintering and infiltration. Benefits of ST-100 include that it is a magnetic material and can be fixtured using magnetic chucks and that the finer particles allow for greater feature definition, sharpness of corners and strength of green parts.