Intro
14%
Pre-heat strategy: getting the die to operating temperature without killing it
Why a cold die under a hot billet writes off the first few parts and a piece of the die's service life with them, and how induction, gas-ring, and oven preheats each fit different shops.
A shop runs an H13 closed-die job on a 1600-ton mechanical press. The die comes out of the rack at shop-floor temperature, around 22°C in winter, gets bolted into the bolster, the operator drops a 1100°C billet, and the first three parts are scrap. The crew shrugs. The first three are always scrap. By the fourth hit the die is "warm enough" and parts hit tolerance. The shift continues. The die runs 42K hits before it is pulled with a heat-check network worse than the same job got on a sister die at the same hit count. Nobody on the floor connects the two.
The connection is the first hit on a cold die. This lesson is about not doing that.