Within the metal and wire forming world, there are several common situations where a given metal material must be broken down so it can be re-formed into the proper shape. Two of the most common processes used for this purpose, processes that are often confused with each other, are known as melting and sintering.
At J & J Spring Enterprises, we’re proud to offer detailed wire forms and wire forming services to all our clients, utilizing a variety of materials and wire form styles. What are the differences between the melting and sintering processes used for breaking down metals before they are formed, and why are these processes often confused? This two-part blog will dig into the answers to all these questions to help you better understand how one of our most important functions is carried out.
Unfortunately, many without experience in this realm often assume that sintering is just another name or format for melting. Simply put, this is not the case.
We’ll get into the nitty gritty details in a moment, but the primary factor at play here is melting point. While melting, as the name suggests, involves heating the metal all the way to the point of full liquefication, sintering does not achieve this level of heat – rather, it uses a combination of heat and pressure to achieve the desired shape.
To get a bit more specific, metal sintering is a process that involves fusing particles together into a solid mass that represents the final product. Both heat and heavy pressure are used. Going a bit further, sintering actually isn’t a metal-only process – it can also be done on various ceramics, plastics and many other materials as well.
Sintering Metal Process
Nearly all metal types can be sintered, and most will first undergo a powdering process in advance to increase their strength and structural integrity. From here, the sintering process will go as follows:
- The materials will be heated in a furnace at a temperature that begins the creation of martensitic, crystalline structures. These structures are only partially compacted, and will be fully consolidated using tools to press the materials together using force. In other cases, the particles may be joined by cold welds.
- As density increases, materials eventually merge. There are a couple liquid phases that might be utilized here, mostly depending on whether iron is involved.
- Finally, the original sintering powder materials have become mostly solid. More liquid and binder additive will flow into open cracks or pores, binding the entire mass together to create a final product.