Steel and aluminium forging: from bar stock to forgings, tolerances and tooling costs
How is a forging made to drawing, and what affects its manufacture? Closed-die forging of steel and aluminium starts with a billet cut from bar stock, which is heated and shaped in a die. Material, tolerances, machining allowances and quantities need to be agreed before production begins.
At Extra Forge in Maribor, Slovenia, we address these questions when preparing custom forgings. Below we explain the process and share practical, indicative figures from our production experience.
From round bar to forging
Our usual production uses the following incoming bar diameters:
Material | Usual bar diameter |
Steel | Ø 18–65 mm |
Aluminium | Ø 25–60 mm |
These ranges are also related to our induction-heating equipment. They describe the incoming stock, not the finished forging dimensions.
The bar is cut to a length calculated from the material volume required. We account for the component geometry, machining allowances and material removed during the process.
The billet is induction-heated to a temperature suitable for the selected steel or aluminium alloy, then forged in a die that shapes the part.
After forging, the flash or excess material along the parting line is removed in a trimming tool. Surface cleaning, such as blasting, follows. Heat treatment and machining are included where required; their exact sequence is defined by the process plan.
Tolerances: what is achieved by forging and by machining?
A tolerance defines the permitted dimensional variation. A machining allowance is material deliberately left on the forging for subsequent removal.
The forging drawing can therefore differ from the finished component drawing. For a flange, the body may remain as-forged while the mating face is machined to the specified dimension, flatness and surface roughness.
There is no single tolerance figure that applies to every forging. Achievable tolerances depend on material, size, geometry and process. Critical dimensions and surfaces requiring machining are therefore agreed before tooling manufacture.
Generic forging with an orange surface indicating planned machining. This illustration is not a manufacturing drawing and does not depict a customer's component.
What does forging and trimming tooling cost?
For a relatively simple steel or aluminium forging with a net mass of approximately 1–2 kg, our experience indicates a tooling manufacture cost of approximately EUR 5,500–9,500 per set.
The set includes forging and trimming tooling. This amount covers tooling manufacture, excluding design, modelling and other development services. It is the tooling cost, not the price of an individual forging.
For this type of component, our indicative forging-die life figures are:
Forging material | Indicative die life |
Steel | Approximately 30,000 pieces |
Aluminium | Approximately 60,000 pieces |
Actual die life depends on alloy, geometry, specified tolerances, loads and maintenance. These figures provide a basis for estimation, not a guarantee for every component.
Frequently asked questions before ordering
Does every forging require machining?
No. Further machining is required on surfaces whose dimensional or surface-quality requirements exceed the agreed condition after forging and cleaning.
Does the tooling price determine the forging price?
No. Material, material consumption, manufacturing complexity, batch size and additional operations also affect the part price. Tooling is therefore considered separately in the quotation.
Have a drawing for a steel or aluminium forging?
Send us the drawing, material designation and expected quantities for a quotation. A 3D model, identified critical tolerances, heat-treatment requirements and required delivery condition are also helpful.
Extra Forge uses this information to assess forging feasibility, required tooling and subsequent manufacturing operations.
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