Stainless Steel Gear Powder Metallurgy: 304 Gear Density 7.5g/cm³ Optimization & Tooth Surface Accuracy Class 6 Control
What Is 304 Stainless Steel Powder Metallurgy Gear
Powder metallurgy (PM) produces gears from fine metal powder.304 stainless steel is widely used for corrosion resistance and stability.PM 304 gears balance cost, performance, and mass production.Ideal for automotive, machinery, electronics, and precision instruments.Key targets: stable density at 7.5g/cm³ and tooth accuracy ISO Class 6.
Why Density 7.5g/cm³ Matters for 304 PM Gears
Density directly affects strength, hardness, and durability.7.5g/cm³ is the optimal density for 304 PM gears.Below 7.5g/cm³: low strength, high porosity, short service life.Above 7.5g/cm³: difficult to sinter, easy to deform, high cost.7.5g/cm³ delivers balanced toughness, wear resistance, and dimensional stability.
How to Optimize Density to 7.5g/cm³
Powder Selection
Use high-purity 304 stainless steel powder.Control particle size distribution for better flow and compaction.Uniform powder reduces internal gaps.
Compaction Process
Use high-precision press at 500–800 MPa.Ensure even pressure across the gear shape.Improve green density to 6.8–7.1g/cm³.Stable green body supports final sintered density.
Sintering Control
Sinter in vacuum or nitrogen–hydrogen atmosphere.Temperature: 1350–1380°C.Holding time: 2–3 hours.Slow cooling reduces deformation.These steps lift density to stable 7.5g/cm³.
Post-Processing
Repressing or sinter-hardening can fine-tune density.Avoid over-compaction to prevent tooth distortion.
Why Tooth Surface Accuracy Class 6 Is Critical
ISO Class 6 is high precision for powder metallurgy gears.Ensures smooth meshing, low noise, low vibration.Reduces wear and extends gear life.Required for precision transmission systems.Class 6 is a top standard for mass-produced PM gears.
How to Control Tooth Accuracy to Class 6
Mold Design & Machining
Use high-precision mold with ±0.002mm tolerance.Ensure accurate tooth profile and pitch.Mold quality determines basic gear accuracy.
Compaction Stability
Uniform pressing avoids density differences.Density imbalance causes shrinkage variation.Stable compaction = consistent tooth shape.
Sintering Deformation Control
Use dedicated sintering fixtures.Prevent tilting or warping during heating.Control heating and cooling rates.Minimize dimensional change.
Finishing Operations
Honing, shaving, or grinding for final correction.Remove tiny sintering errors.Stabilize accuracy to Class 6.
Common Defects & Solutions
Low Density
– Cause: uneven powder, low pressure, insufficient sintering.– Fix: optimize powder, increase compaction, adjust sinter curve.
Tooth Inaccuracy
– Cause: mold error, deformation, uneven shrinkage.– Fix: precision mold, fixtures, post-finishing.
Porosity
– Cause: low compaction, poor sintering.– Fix: higher pressure, proper temperature and atmosphere.
Performance Advantages of Optimized 304 PM Gears
– Stable density at 7.5g/cm³.– Tooth precision ISO Class 6.– Strong corrosion resistance.– High wear resistance and fatigue life.– Low noise, smooth operation.– Cost-effective for mass production.
Application Fields
– Automotive transmission parts.– Precision machinery.– Medical devices.– Electronic actuators.– Food and chemical equipment.
Conclusion
304 stainless steel powder metallurgy gears need stable density and high precision.7.5g/cm³ density and Class 6 tooth accuracy are achievable with proper process control.Optimize powder, compaction, sintering, and finishing.The result is high-performance, reliable, cost-effective gears for industrial use.
