What Is a Stripper Bolt?
A stripper bolt is a specialized bolt primarily used in mold applications. It controls the vertical movement range of the mold stripper plate, hence its name. The bolt is distinguished by a section of the shank that is thicker than the rest, directly below the bolt head, leading to its alternative name, “stepped bolt.”
Applications of Stripper Bolts
1. Mold Parts
Stripper bolts guide the upper and lower parts of the mold stripper plate. They maintain the stripper plate’s position by fitting through holes in the backing plate, ensuring smooth separation of molded products during disassembly. Precise body length is crucial to prevent tilting of the stripper plate, which could hinder mold function.
2. Coil Spring Guide and Stopper
Stripper bolts also serve as guides and stoppers for devices using, stabilizing the spring’s vertical movement.
3. Guide for Vertical Sliding Parts
The bolts’ bodies can act as guides for vertical sliding components, though they should not be subjected to lateral forces or bending loads.
Principle of Stripper Bolts
The outer diameter of the stripper bolt’s body below the head acts as a sliding guide, with the body length limiting vertical movement range. The dimensions are precisely finished to specific tolerances to ensure fit and function. The step feature results in a thread diameter smaller than the bolt’s head diameter, with tightening features designed to match this discrepancy. Materials include carbon steel, chromoly steel, and stainless steel, all hardened for enhanced strength and wear resistance.
Types of Stripper Bolts
1. Male Thread Type
These bolts have an external thread and can be screwed directly into a tapped hole, though they are prone to stress concentration at the threaded base.
2. Female Thread Type
Featuring an internal thread, these bolts are secured with another bolt from behind, reducing stress concentration and offering a more secure fix.
3. Bush Type
This design separates the threaded part and body, reducing stress concentration and allowing for single-sided tightening. The bush requires a thicker body diameter to ensure structural integrity.
4. Head Shape
The heads often feature a hexagonal socket to prevent them from dislodging from the die set, with variations including low-profile heads and large-diameter heads with knurled edges for tool-less tightening.
Other Information about Stripper Bolts
Precautions for Stripper Bolts
It’s important not to confuse stripper bolts with similarly shaped plastic bolts or shoulder bolts, as each serves different purposes and load directions. Stripper bolts are suitable for tensile loads along the bolt axis but not for applications requiring lateral or bending loads, for which shoulder bolts are designed.