Closed die steel forging-sometimes referred to as “near-net-shape” or “impression die” steel forging – offers numerous technical advantages, saves on material usage, and carries an upfront tooling investment that’s not nearly as expensive as some people think.
Improved Strength to Weight Ratio
In the closed die forging process, metal bar or billet is heated before being placed in the die then hammered until the metal completely fills the die cavity.
During this process the material’s grain structure becomes compressed and aligned to the component shape which imparts greatly increased directional strength with reduced stress concentrations in corners and fillets. Components manufactured this way are stronger than their equivalent machined-from-solid or cast parts.
Forging a component greatly reduces the possibility of metallurgical defects such as porosity or alloy segregation as found in some castings. This leads to reduced scrap, a uniform response to heat treatment and predictable component performance in the field.
There is virtually no possibility of porosity being introduced during the forging process. Even this can be checked with a low cost ultrasonic test after manufacture. The possibility of small surface cracks can be managed with a simple crack detection procedure towards the end of the process.
Moving from machined-from-solid to forged components generates a saving in raw material usage. Starting from a nearnet- shape forging can also reduce machining times. This means companies moving from machine-from-solid to machine-from forging can generate enough capacity on their existing plant to save capital outlay on new machinery, as their business grows.
Customers often assume that the initial tool cost required for near net shaped forging is prohibitive. In fact, forging dies and tools are quite simple in construction and are relatively low cost, making them viable even for jobs with low production quantities. This cost can be further mitigated by amortisation into the component piece price and even reclaiming pre-used die materials.