Forging

Forging shapes hot or cold metal by pressing or hammering it, which gives the part a continuous grain flow and makes it stronger than a part cut from bar or cast. It is used for flanges, shafts, gears, connecting parts, valve bodies and fittings.

Closed-die forging presses heated steel into a shaped die and suits repeat parts. Open-die forging shapes larger, simpler parts between flat dies. Brass hot forging makes fittings and valve bodies, ring rolling makes seamless rings and flanges, and cold forging or cold heading makes bolts, rivets and pins.

Forged parts are usually trimmed, heat treated, shot blasted and machined to the final size. Many forge shops machine in-house or with partners.

Materials commonly used

• Carbon steels such as EN8 (C45) and EN9
• Alloy steels such as EN19, EN24 and 20MnCr5
• Stainless steels
• Forging brass (CuZn40Pb2)

What to send with your requirement

• A drawing of the finished part, with machined faces marked, and a 3D model if available
• The material grade and any standard it must meet
• The quantity per order and per year
• Heat treatment and hardness required, and whether you need a test certificate
• Whether you need the forging only or the finished, machined part

What affects the cost

• Die cost for closed-die forging, shared over the parts
• Forging weight, the material and its price
• Machine size: hammer or press capacity needed for the part
• Heat treatment, testing and machining
• Quantity per batch, since dies and setups are spread across it

Common mistakes to avoid

• Sending only the finished-part drawing without saying the forge should add machining allowance
• Not specifying the material grade and heat treatment
• Choosing closed-die forging for a handful of pieces, where open-die forging or machining may suit better
• Not agreeing on inspection, such as hardness and ultrasonic testing

Frequently asked questions

Why forge instead of machining from bar?

Forging puts the grain flow along the shape of the part, which improves strength and fatigue life, and it saves material on larger quantities. For a few pieces, machining from bar is often simpler.

Do forging dies cost extra?

Closed-die forging needs a die made for your part, usually paid once. Open-die forging uses general tools, so it suits low quantities and large parts.

Can I get a forged and machined part from one workshop?

Many forge shops machine in-house or through partners. Say what you need in your requirement so the quote covers the full job.