Step 2 of 5
38%
Running forge dies: why this course exists
The same die, built to the same print and treated to the same spec, lasts 30K hits in one shop and 120K hits in another. The spread lives in four operator-controlled levers, and that gap is the subject of this course.
Step 2 of 5Preheat as the first lever
The die has to be at operating temperature, or close to it, before the first hot billet lands. A cold die struck by a 1100°C billet sees a surface spike of several hundred degrees Celsius in milliseconds while the bulk stays at shop-floor temperature. That gradient initiates heat-checking inside the first few hundred hits. Preheat to 200-400°C, hold the soak until the surface-to-core delta closes, and the gradient is bounded inside the window the H13 was tempered to survive. Skip preheat to clear 30 minutes of changeover time, and the die loses 20-40% of its potential life on the first ten parts. Lesson 2 covers preheat methods, soak times, and how to set the surface-to-core delta. (FIA / Michigan Tech preheat-evaluation paper; Hawryluk et al., MMTA 2020.)
Quick check
An operator argues that the first three parts of every shift are scrap anyway, so the press might as well start hitting on a cold die. What is the engineering objection to that position?