Stripper Bolts for Die Stripping
A stripper bolt does two jobs at once: it guides the stripper plate and it lets that plate travel.
That dual role is why a stripper bolt is not a cap screw with a long shank. The shoulder is ground to act as a guide; the thread holds the plate to the die. Get the shoulder length wrong and the stripper plate either bottoms before the springs compress or hangs up short of the strip.
Start with the function
Stripper travel
The precision-ground shoulder gives the stripper plate a straight path and controls how far it can lift. Shoulder length sets the usable travel.
Springs and preload
Stripper bolts work as a system with the springs behind the plate. Match the spring class to the force the strip needs before sizing the bolt.
Die set alignment
The bolts hold the stripper plate square to the die set. If the plate racks, the bolts take a side load they were not designed for.
What to look for
Material and hardness. Stripper bolts are made from alloy steel (4140, 41xx series), heat-treated to 37-42 HRC. Soft enough to machine the thread, hard enough that the shoulder resists the scuffing that comes with thousands of stripper strokes.
Shoulder, not shank. The working surface is the ground shoulder - it runs in the stripper plate bore. Specify the shoulder diameter to the fit the plate needs, and the shoulder length to the travel the strip requires.
Thread engagement. Minimum 1.5x the screw diameter in steel. A 3/8 in. bolt needs at least 0.56 in. of thread. Short engagement is where a stripper bolt eventually breaks - at the thread root, not the shoulder.
Torque it lubricated. Tighten in a cross pattern in three passes - 50%, 75%, then 100% - with lubricated threads. An unlubricated high-strength fastener can reach 70% of yield before the torque spec is even met, which is how threads gall and heads strip.
Plating near cooling. Where a bolt sits close to a cooling circuit, specify black oxide or zinc-nickel plating. Moisture there is what turns a removable bolt into a corrosion-bound one.
Send us the shoulder diameter, shoulder length and thread - we will match the bolt. Request a quote or call 814-438-7657.