Forge Post-Processing
Forge post-processing plays an important role in the success of a forging process. This includes the processing of existing raw forgings prior to sale, as well as post-processing that must be performed after the forging has been completed. Because of the importance of post-processing, many forges employ post-process specialists who specialize in different aspects of the post-processing process.
Post-processing such as machining, grinding, honing, polishing, and coatings are often employed to remove imperfections, burrs, and scale, improve strength and hardness or reduce residual stresses. Often, finishing processes must be performed to achieve a desired dimensional accuracy, surface finish, and appearance. Although many post-processing steps can be done by the forge itself, depending on the complexity and amount of work required, it may be beneficial to outsource some or all of the post-processing work to another supplier.
Heat treat post-processing is often employed to harden and/or strengthen raw forgings and other parts. Heat treating can include annealing, quenching, tempering, and normalizing. Heat treatment is often followed by temper, or stress revival processes. These processes remove or reduce residual stresses, increase dimensional accuracy, and reduce distortion caused by the heat treat process.
Shot peening is an effective post-processing tool that can be used to increase fatigue strength and service life, improve uniformity and finish of forged parts, and reduce distortion. Shot peening systems consist of a mass of shot media propelled toward the part with a high velocity, which causes surface deformation and compressive residual stresses, resulting in the desired benefits.
Additive manufacturing and subtractive post-processing processes are becoming more common in the forge industry and have enabled forges to produce complex parts with greater efficiency and quality. Additive Manufacturing post-processes such as metal deposition and powder bed fusion, along with subtractive post-processes such as machining, milling, and drilling, are often employed to further improve the accuracy and quality of a forged part.
Surface coating is one of the most widely employed post-processing techniques and has both aesthetic and functional benefits. Mechanical plating, cadmium plating, and electroless nickel plating are all common surface coatings used to improve hardness, wear resistance, and corrosion resistance.
Overall, any forging process is only as good as the post-processing that follows. It is important to understand the various post-processing technologies available and what steps are necessary to maximize the parts performance and quality. By working with a knowledgeable post-processing specialist, a forge can be confident that the part or product they produce will have the desired dimensions, finish, and strength.
