Sinter
Though often associated with powder metallurgy, the
heat treating process, sintering, is more broadly applied to include such materials as glass, alumina, silica, zirconia, magnesia, lime, ferric oxide, organic polymers and more. While not all materials can be combined in this manner, distinctive material compounds are more readily made through the use of sintering than any other production process. Aerospace, food processing, electrical, automotive, pharmaceutical, transit, medical, machine building, computer and securities industries all depend upon sintered parts such as brake pads, ski and snowboard materials, armatures, bushings, magnetic parts, counterweights, gears, cams, filters and even dental crowns. Each of these sintered components has several advantages over products produced through alternative manufacturing processes such as stamping, forging or molding. High purity of raw materials, stability, uniform purity and uniform density are common characteristics of sintered parts. Additionally, sintering reduces waste and any resulting added expenses as approximately 97% of materials end up in the finished product. Though not all, many sintered parts need no secondary fabrication providing further time and economic value to this
heat treatment.
Sintering inherently begins with the reduction of raw materials through atomization, flaking or any other technique which produces a fine dust or powder. Measured amounts of these powders are then placed into a compaction die or other mold where pressure is applied in precise amounts. This form is ejected from the die and sintering begins. The form is placed in a controlled-atmosphere furnace, or in the case of continuous run operations on a conveyor belt that will transition through the furnace. From this point in the manufacturing process there are two different types of sintering, liquid phase and solid state. In liquid phase, at least one but not all of the raw material is heated above its melting point causing this fluid to flow throughout the capillaries of the still solid particulates and create an extremely dense product. Alternatively in solid state sintering the temperature reaches only 2/3 of the melting point for the least heat resistant material ensuring a lack of liquefaction. The temperature controls of this equipment are very precise. While the resultant products differ slightly in composition, both alter the existing mechanical bonds and allow the powdered components to adhere to one another, thus creating a uniform solidly constructed part.
