1.SLS laser powder sintering
The general process is as follows: firstly layer a layer of powder on the substrate, and after pressing the roller, a layer is selectively sintered by a laser. A new layer of powder access paving device is then placed over it, and the next layer of sintering is carried out and repeated until the final part is obtained. At present, there are two commercial SLS processes: one is the Rapid and Tool technology of DTM Company of the United States; the other is the Direct and Tool process of EOS of Germany.
(1) Rapid, Tool process
The process uses laser sintering of the steel powder coated with the binder, the computer scans the scanning path of the laser beam, and the heated and melted binder bonds the metal powder together to form a part having a porosity of about 45%, and is dried. After that, it is placed in a high-temperature furnace for sintering and copper infiltration to form a surface-hardened part. At this time, the upper material of the part is 65% steel and 35% copper. After the post-treatment process such as grinding, the final mold is obtained.
(2) Direct, Tool process
The low-melting point metal is infiltrated into the base metal powder by the sintering process to increase the powder gap, and the dimensional expansion compensates for the sintering shrinkage, so that the final shrinkage rate is almost zero.