Many people unfamiliar with forging see it as a single-step process involving hammering or pressing, but in practice, three critical steps must be followed to ensure consistent, defect-free, high-quality parts. In the forging industry, these are referred to as busting, blocking, and finishing when forging in a press.
All three stages are performed in quick succession while the billet is still hot, so careful planning is required to ensure quality results. Additionally, a different impression is used for each stage, and designing this tooling is a complex task that involves determining the required grain flow and amount of deformation needed at each step.
In this article, we’ll discuss each of these stages in more detail.
Busting
During busting, the billet, hot from the furnace, receives its first compression and is shaped into a preform that can subsequently produce the required part.
Often, this means applying a radial load to flatten a cylindrical billet. Busting also adds the profile changes needed to ensure the material is in the right places for the next step. Any corners that are needed have generous radii, and draft angles are large.
Busting initiates the grain flow that is sought after in forged parts, so the tooling used in this stage is designed to ensure grains begin to flow in the desired direction. It also has an added benefit of breaking mill scale away from the raw material.
Blocking
This stage of the forging process creates the initial definition of the net shape but the part is still fairly nebulous. Material is pushed into the die cavities to create a shape that resembles the required part but lacks fine detail. Flash is allowed to form around the parting line and is used to control how the die fills. Corner radii are tightened, and draft angles are steepened.
For grain flow, it’s this blocking stage that creates the final alignment, and where strength properties are set, so close attention is paid to how the metal will move under pressure.
Finishing
This last stage of the forging process creates the fine detail needed for a finished part before flash is trimmed away. During the finishing stage, corner radii are tightened, draft angles are steepened, and fine detail, such as raised lettering, are added. Material properties, along with the type of equipment used, influence the finishing process.
How Trenton Forging Ensures Precision Throughout Our Process
Companies in industries from defense and agriculture to heavy truck and marine value Trenton Forging’s ability to deliver highly consistent forgings. Our reputation for quality results from the knowledge we bring and our attention to detail.
Every aspect of our impression die forging process, including die maintenance, is handled in-house, and we use advanced and efficient technology, including CNC saws, induction heaters, and 3D modeling software, to reduce defect risks and other common forging challenges.
Visit our website to learn more about our unique process, or contact us today to get started with a quote or first article sample.
