This binder is based on agar, a polysaccharide derived from seaweed used as a common food additive. It is water soluble Metal powder is mixed with the water, agar and minor additions to form feedstock pellets that can be easily fed into conventional plastic injection molding equipment. The metal powder employed is typically under about 20 micrometers and is made by gas or water atomization. Compounding into feedstock is done by twin screw extrusion. The feedstock is relatively fluid at 85 C, having the consistency of toothpaste, and is thus easily injection molded into a net shape mold in a manner similar to plastic injection molding.
Primary differences are lower molding temperatures and pressures.
Upon cooling in the mold to near room temperature, the now molded feedstock drops below its gelation temperature, setting into a green part and allowing it to be removed. Cycle times are on the order of half a minute, depending on part size. After approximately 1 hour in ambient air, the green part will have dried and is now ready to be sintered. No separate debind step is required as is necessary for traditional MIM feedstocks. Rather, a dwell time of approximately 1 hour in air is incorporated into the beginning of the sintering cycle.