Introduction
Metal powder based forming and forging processes have been widely used in the manufacturing of engineered components in the aerospace, automotive and other industries. This is due to the numerous advantages associated with these types of processes such as improved homogeneity, reduced fatigue damage and improved surface finish, decreased machining time, as well as improved dimensional accuracy. In recent years, powder preforming processes have increasingly being used as an alternative to conventional forging processes in the production of complex components with challenging shapes.
Powder preforming is a process for forming complex parts from metallic powders. It is similar to the forging process, but the workpiece is made from a striking powder, instead of from a solid piece of material. The powder preforming is done in a die, which is a steel tool that has a cavity that is the same shape as the desired part. The powder is pressed into the die and then heated to sinter the powder particles together; forming a bonded metal part.
The powder preforming process is particularly useful for the manufacture of complex shapes, as it is possible to form any shape into the metal powder. The process also has the advantage of reducing fatigue damage, which can be a problem in traditional forging processes. Powder preforming also has the benefit of being less expensive than traditional forging processes, as the cost associated with designing and constructing the die is much lower.
The main disadvantage of powder preforming is that the material properties of the formed parts are usually lower than those obtained with conventional forging processes. This is due to the powder particles being much smaller than those used in forging, leading to lower levels of material strength and stiffness. In addition, powder preforming also results in parts with rougher surfaces, due to the powder particles not completely filling the mold during preforming.
To improve the material properties of powder preformed parts, hot forging can be used. Hot forging is a process that involves the reheating of powder preformed parts and then subsequently subjecting them to compression or pressure to obtain the desired dimensional profile. The hot forging process allows the preformed part to obtain the material properties that are comparable with that of conventionally forged parts, as it promotes recrystallization of the grains, which leads to an increased strength, stiffness and improved surfaces.
Conclusion
Powder preforming is a process that is increasingly being used in the manufacturing of components from metals, as it is capable of forming complex shapes with improved dimensional accuracy. However, the material properties of powder preformed parts are usually lower than those produced with conventional forging processes. To remedy this, a hot forging process can be used to improve the strength, stiffness and surface finish of the preformed parts. With hot forging, parts can be produced with material properties that are comparable to those obtained with traditional forging processes; making the powder preforming process a viable alternative for the manufacturing of complex shaped components.
