Deposition Processes

There are several materials which can be formed with SDM including metals, plastics, and ceramics. We use several alternative processes to deposit these materials including extrusion, 2-part resin systems, hot wax dispention, photocurable dispention, microcasting, welding, and thermal spraying.

	Extrusion: Thermoplastic materials are deposited with an extruder supplied by Adavanced Ceramics Research (ACR) Corporation. Several part materials are available, including 'green' ceramics (e.g., alumina and silicone nitride) and polycarbonate. For support material, we use ACR 200 which is a proprietary non-ionic, water-soluble, machinable thermoplastic.
	Polyurethanes and Epoxies Resins are deposited as 2-part resin/activator systems. For support material, we use a wax which is removed by melting. Waxes can be deposited with a hot-melt dispension system.
	Waxes can be deposited with a hot-melt extrusion system.Waxes can be used as either part or as support materials, depending upon the application. For example, wax is used as a support material for making parts with resin systems. We also make wax parts using water soluble, photocurable support materials
	Photocurable Resins can be deposited with simple a simple syringe pumping system. We use water-soluble photocurable resins as support materials for wax parts.
	Microcasting is a non-transferred welding process which deposits discrete, super-heated molten metal droplets to form dense. metalurigically bonded structures. Materials for microcasting include stainless steel and copper. Copper can be used as a support material which is removed by etching in nitirc acid. An arc is established between a tungsten electrode and feedstock wire which is fed from a charged contact tip. The wire melts in the arc, forming a molten droplet at the end of the wire. When the droplet has accumulated enough molten material, its weight overcomes the surface tension by which it adheres to the wire. The droplet falls from the wire, is accelerated to the underlying substrate by gravity, and flattens upon impact. Due to a large volume-to-surface ratio, they remain superheated in flight and contain sufficient energy to locally remelt the underlying substrate to form metallurgical bonding upon solidification. To control oxidation, the droplets and working area are locally shrouded with a laminar curtain of shielding gas. For this purpose, we use a commercially available shrouding device from Praxair, Inc., 777 Old Saw Mill River Road, Tarrytown, NY, 10591-6799. We typically use micocasting to deposit stainless steel and copper.
	Metal Inhert Gas (MIG) Welding is used to deposit steel alloys at a high depsoition rate.
	Thermal Spraying can be used to spray thin layers of high-performance materials. We have several types of systems including plasma sprayers (see figure at left) which can deposit metals, plastics, and ceramics. We also have 2-wire electruic systems for depositing metals at a high deposition rate.