How are Forging Dies Constructed ?

Forging Dies are Constructed from high-grade carbon or alloy steel and must resist heat, abrasion and pressure. They must withstand severe strains, have a long wear under high production conditions, and minimize checking. The majority of  die blocks are heat-treated before impressions are machined to avoid wrapping and cracking.

Dies are sunk, that is the cavities are formed, by milling, electric discharge machining or sometimes by ceramic casting processes. Machining and shrinkage allowances and draft must be built in just as in patterns for casting. Draft may be form 3* to 10* depending on the part size. Additionally, flash gutters are cut into the die to handle extra meal. 

Die life varies widely due to many factors such as metal being forged (steel, aluminum, etc.), the amount of scale on the part, the depth of  impressions, and the temperature and uniformity of the slug or preform. The type and proper application of lubrication is also important.

In general, impression-dies last 15000 to 30,000 platters before they need reworking. A platter is the forging with its surrounding flash. Each platter may contain from one to six parts.

The dies are often made in sections, called inserts, fitted in to the die block. This is economical, as the blocker section may last several times as long as the finish forging section. 

Locking surfaces or pins can be provided so that the two dies will match the same way each time they come together.