PM35 porous breathable steel (also called vent steel or PM-35) is a powder-metallurgy-based porous metal material with a uniform network of interconnected micro-pores (7–35 μm in diameter) and a porosity of 20%–30%. It is made by sintering high-purity stainless steel powder at high temperatures.
PM35 porous steel is a specially engineered sintered material with a uniform network of microscopic pores. These pores give it unique gas‑permeable properties while still maintaining the mechanical strength required for injection mold tooling. It is widely chosen in injection molding for the following reasons:
1. Efficient Venting of Gases
During the injection process, trapped air, volatile compounds, or gases from molten plastic can cause short shots, burn marks, bubbles, or weld lines. PM35 allows these gases to escape uniformly through its porous structure, eliminating such defects.
2. Improved Part Quality
By releasing trapped gases, PM35 helps achieve better surface finish, higher dimensional accuracy, and fewer rejects, leading to more consistent production quality.
3. Reduced Cycle Time
With efficient venting, injection pressure requirements are lower, cooling is more uniform, and cycle times can be shortened, improving overall productivity.
4. Durability Under High Loads
Compared with standard porous materials, PM35 retains good mechanical strength, allowing it to withstand the pressure and stress of high‑volume injection molding environments.
5. Versatile Applications
PM35 porous steel can be used in mold inserts, vents, core pins, and areas where gas entrapment is likely. It is especially effective for complex geometries, thin‑wall parts, and materials prone to degassing.
