Porous Steel, PM-35, Venting Material, Porous Material, Venting Steel, Exhaust Steel Tool Steel
Description of Porous Steel Material
Porous steel is a type of stainless steel made from fine spherical powder particles sintered at high temperatures, uniformly filled with tiny exhaust pores in all directions. Also known as porous material or porous metal, it is used in injection molds to address gas trapping issues. The technology is provided by International Mold Steel, Inc. (USA) and manufactured by Sintokogio, Ltd. (Japan).

Delivery Condition: Pre-hardened to HV350-400 (HRC35-40).

PM-35 porous steel is a high-quality "breathable" steel refined through powder sintering technology. It contains a series of fine pores with a diameter of 10 micrometers, accounting for 20%-30% of the total steel volume. This unique structure not only provides ventilation but also maintains the high strength, hardness, and corrosion resistance required for injection molds. Therefore, embedding PM-35 porous steel in appropriate locations of injection molds can completely eliminate injection problems caused by gas, making the molding process more perfect.

Additionally, PM-35 porous steel possesses excellent mechanical properties. It can be processed using the same methods as conventional mold steels, such as cutting, grinding, and electrical discharge machining. The formation of porous steel primarily involves countless steel balls compressed together. Depending on the material of the injected product, three types of porous steel with different pore sizes are designed using steel balls of three different diameters. These uniform spherical steel balls undergo high-temperature sintering and a series of high-tech processing steps to form a material essential for plastic molds—capable of gas permeability while maintaining hardness and strength. This can be considered a revolutionary advancement in solving gas trapping issues in plastic molds.
Alternative Names for Porous Steel
Due to user preferences or regional variations, a product is often referred to by various names.

Here are some other names for porous steel: exhaust steel, exhaust pin, venting steel, porous metal, venting material, porous steel, porous material, porous metal, venting cylinder, Japanese Sintokogio porous steel, PORCERAX Ⅱ porous steel, PM-35 porous steel, etc.
Porous Steel Models
There are three models:

PM-35-7 micron (7 micron small pores),

PM-35-25 micron (25 micron medium pores),

PM-35-35 micron (35 micron large pores)
Composition of Porous Steel
Chemical Composition % (for reference only)
Carbon C 0.012
Silicon Si 0.07
Chromium Cr 16.5
Nickel Ni 1.2
Manganese Mn 0.17
Molybdenum Mo 1.9
Comparison Standards and Features
Special sintered powder steel
Applications
Suitable for plastic and die-casting molds to address quality and efficiency issues caused by gas trapping
Physical Properties of Porous Steel
Model
PM-35
Average Pore Size
7μm-3μm (25μm-15μm) (30μm-20μm)
Porosity ~25%
Density
6.3～6.5g/cm3
Linear Expansion Coefficient (at 20～150℃)
12.0～12.5*10??/℃
Thermal Conductivity (at room temperature)
0.07～0.08 cal/cm·sec·℃
Bending Strength kgf/mm2
70～75
Tensile Strength kgf/mm2
45～50
Hardness (HV)
350-400
Machinability
Good
Characteristics of Porous Steel
1. Reduces injection pressure and shortens molding and holding times.
2. Reduces and eliminates internal stress in molded parts, preventing deformation and warping.
3. For plastic parts with surface textures, it addresses the issue of glossy textures caused by high temperature and pressure, meeting requirements for matte surfaces.
4. Due to the tight fit of mold parting surfaces, it resolves difficulties in mold opening. It addresses issues where ejector pins and inserts cannot provide sufficient surface area to accommodate large amounts of gas, avoiding flash and other defects caused by parting surfaces or other venting systems.
5. Helps resolve or alleviate challenging molding issues such as gate misalignment, uneven wall thickness, and thin-walled products.
6. Fully addresses defects like burning, flow marks, short shots, and part deformation caused by gases from high-temperature molding materials and rapid pressure buildup in the mold cavity.
7. Improves molding production efficiency and reduces production costs.
Advantages of Porous Steel Compared to Traditional Steel
1. Solves injection molding issues: Utilizes the permeability of PM-35 porous steel to address challenges such as gas trapping, weld lines, incomplete filling, and burrs.
2. Reduces waste: PM-35 porous steel resolves injection molding issues, reducing production waste and minimizing damage to molds.
3. Quality control: Products made with PM-35 porous steel exhibit good quality, dimensional stability, and reduced need for post-processing, thereby enhancing productivity.
4. Energy savings: Air in the mold cavity during injection is smoothly released through the fine pores in the mold, reducing cushion pressure and energy consumption.