Table of Contents
Note: This page summarizes a representative application example. Results are specific to the described design, validation scope, and production conditions.
Executive Summary
Client: Agriculture equipment OEM (tractors, harvesters) Challenge: Machined transmission gears too expensive, long lead times Solution: FN-0408 PM gears with carburizing heat treatment Results:
- 35% cost reduction per gear set
- Service life doubled (4,000 to 8,500 hours)
- Lead time reduced from 8 weeks to 3 weeks
- Consistent quality (Cpk 1.5 vs 1.1)
Customer Background
Industry: Agriculture machinery manufacturing Application: Tractor transmission gearbox (mid-range 80-120 HP) Environment:
- Shock loading (field conditions, obstacles)
- Mud, dust, moisture exposure
- Temperature range: -20 deg C to +60 deg C
- Intermittent lubrication
Original Design: CNC machined 8620H carburized steel gears
The Challenge
Problem 1: High Manufacturing Cost
- Issue: CNC machining from bar stock generated 70% waste
- Cost: $18.50 per gear (material + machining + heat treatment)
- Impact: Pressure to reduce BOM cost for price-competitive market
Problem 2: Long Lead Times
- Issue: 8-week lead time (machining backlog)
- Impact: Inventory carrying costs, limited flexibility
Problem 3: Quality Variation
- Issue: Gear tooth profile accuracy varied by machinist/setup
- Metric: Cpk 1.1 (marginal process capability)
- Impact: Noise complaints, premature wear in 5-8% of units
SinterWorks PM Solution
Material Selection: FN-0408
Why FN-0408?
- 4% Nickel + 8% Copper = excellent hardenability
- Responds well to case hardening (58-62 HRC surface)
- Core toughness (30-35 HRC) resists shock loading
- Cost-effective vs 8620H steel
Manufacturing Process
- Precision Compaction: 650 MPa, custom gear tooling
- Sintering: 1120 deg C, 25 minutes
- Sizing: Re-strike in precision dies (+/-0.05mm tooth profile)
- Case Hardening (Carburizing):
- 920 deg C, 4 hours in endothermic gas
- Case depth: 0.8-1.2mm
- Oil quench + temper at 180 deg C
- Final hardness: 60-62 HRC surface, 32-35 HRC core
Design Optimizations
- Tooth count: 42 (module 2.5)
- Pressure angle: 20°
- Face width: 25mm
- Hub diameter: 35mm (spline interface)
- Chamfers added to prevent chipping during assembly
Testing & Validation
Gear Tooth Strength Testing (ISO 6336)
| Property | PM FN-0408 | Machined 8620H | Comparison |
|---|---|---|---|
| Contact Stress Capacity | 1450 MPa | 1520 MPa | -5% (acceptable) |
| Bending Stress Capacity | 420 MPa | 450 MPa | -7% (acceptable) |
| Surface Hardness | 61 HRC | 60 HRC | Equivalent |
| Core Hardness | 33 HRC | 35 HRC | Slightly lower |
Durability Testing (Accelerated Life Test)
- Test: 200% rated torque, continuous operation
- PM FN-0408: 8,500 hours to failure (tooth pitting)
- Machined 8620H: 4,200 hours to failure
- Result: 2x service life improvement
Reason for Improvement:
- PM microstructure has fine, evenly distributed porosity
- Acts as micro-oil reservoirs to improved boundary lubrication
- Reduced contact fatigue crack initiation
Noise Testing (ISO 1328)
- PM gears: 68 dB(A) @ 1500 RPM
- Machined gears: 72 dB(A) @ 1500 RPM
- Improvement: 4 dB quieter (consistent tooth geometry)
Production Results
Cost Comparison (Per Gear)
| Cost Element | Machined 8620H | PM FN-0408 | Savings |
|---|---|---|---|
| Material | $4.50 | $3.20 | 29% |
| Machining | $9.80 | $0 (near-net-shape) | 100% |
| Heat Treatment | $2.50 | $2.80 | -12% |
| Tooling Amortization | $1.20 | $3.50 | -192% |
| Quality Inspection | $0.50 | $0.30 | 40% |
| Total Per Gear | $18.50 | $12.00 | 35% |
Break-Even Volume: 25,000 gears (tooling amortization) Annual Volume: 120,000 gears to PM highly cost-effective
Lead Time Reduction
- Machined: 8 weeks (material procurement + machining queue)
- PM: 3 weeks (sintering + heat treatment)
- Improvement: 62.5% faster
Quality Consistency
- Dimensional Cpk: 1.5 (improved from 1.1)
- Tooth profile accuracy: +/-0.03mm (vs +/-0.08mm machined)
- Warranty claims: Reduced 78%
Field Performance (2-Year Data)
Tractor Fleet Data (4,500 units)
- Service Life: Average 8,200 hours (vs 4,000 hours baseline)
- Failure Rate: 1.2% (vs 6.8% with machined gears)
- Customer Satisfaction: Noise complaints reduced 85%
Cost Savings (Annual, 120K gears)
- Direct Cost Savings: $780,000/year (35% x $18.50 x 120K)
- Warranty Savings: $145,000/year (78% reduction in claims)
- Inventory Reduction: $60,000 (lower safety stock due to shorter lead time)
Total Annual Benefit: $985,000
Get PM Gears for Agriculture Equipment
SinterWorks produces heavy-duty PM gears for agriculture:
- FN-0408, FN-0205, and custom alloys
- Case hardening in-house (carburizing, carbonitriding)
- Gear tooth accuracy: ISO 6 or better
- Volumes: 10K to 1M+ parts/year
Request a quote: Upload your gear drawings for free DFM evaluation.
Frequently Asked Questions
Can PM gears handle shock loads?
Yes, with proper material (FN-0408) and heat treatment (case hardening). Core toughness (30-35 HRC) absorbs shock while hard case (60-62 HRC) resists wear.
What is the maximum gear size for PM?
Typically up to 200mm outer diameter, depending on press capacity. Larger gears may require segmented tooling or casting/machining.
How does PM gear noise compare to machined?
PM gears are often 3-5 dB quieter due to consistent tooth geometry (less manufacturing variation).
Related Resources
Use these internal links to keep moving through the most relevant guides, service pages, and technical references for this topic.
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FN-0408 High Nickel-Copper PM
Review the higher-strength nickel-copper PM material route used for demanding gear and structural programs.
Powder Metallurgy Gears
Compare tooth quality direction, heat-treatment logic, and production fit for PM gear programs.
Request a Quote
Send your gear geometry, torque target, and annual volume for PM gearbox review and pricing support.