Camera Module PM Structural Components - Application Example

Application Background

Component Function

Structural brackets for optical image stabilization (OIS) camera systems

Requirements

• Tight dimensional tolerances for optical alignment
• Lightweight construction (smartphone weight constraints)
• Non-magnetic properties (near magnetic sensors and actuators)
• Corrosion resistance for device internal environment
• Cost-effective for high-volume production

Original Manufacturing Approach

5-axis CNC machining from aluminum 6061 bar stock

Material Selection: 304 Stainless Steel

Why 304 SS Was Selected

Non-Magnetic Requirement:

• 304 is austenitic, generally non-magnetic
• Critical near magnetic positioning sensors
• Magnetic permeability typically <1.02

Dimensional Stability:

• Low coefficient of thermal expansion
• Maintains dimensions across operating temperature range
• Good for precision optical assemblies

Manufacturing Considerations:

• Suitable for precision PM processing
• Can achieve tight tolerances with proper controls
• Reasonable material cost for consumer electronics

Weight Trade-off:

• Density 7.9 g/cm3 (heavier than aluminum at 2.7 g/cm3)
• Offset by design optimization for PM process
• Final component weight acceptable for application

PM Manufacturing Process

Process Steps

1. Precision Tooling Design
   • Tool design incorporating shrinkage compensation
   • Target tool precision: +/-0.005mm
   • Critical feature location control
2. High-Density Compaction
   • Compaction pressure: 750 MPa
   • Target green density: 7.2 g/cm3
   • Careful fill and compaction control
3. High-Temperature Sintering
   • Sintering temperature: 1280 deg C
   • Atmosphere: High-purity hydrogen
   • Careful temperature control and uniformity
4. Precision Grinding
   • Selected critical surfaces ground to specification
   • Mounting hole locations
   • Flatness-critical surfaces
5. Demagnetization
   • Reduce residual magnetism
   • Target: <0.5 Gauss
6. Passivation
   • Chemical treatment per ASTM A967
   • Corrosion resistance enhancement

Design Features

• Wall thickness: 0.8mm (optimized for PM capability)
• Mounting holes (4x): Dia. 1.20mm
• Critical flatness surfaces identified
• Weight: 0.45g per component

Dimensional Capabilities Achieved

Tolerance Targets and Results

Process Capability: Cpk 1.8-2.1 demonstrated in production sampling

Important Notes:

• Results shown represent this specific application and processing conditions
• Achievement of tight tolerances requires:
  • Precision tooling
  • Process control and monitoring
  • Appropriate secondary operations (grinding)
  • Statistical process control

Cost Analysis

Comparison Framework

CNC Machined Aluminum Approach:

• Extensive multi-axis machining required
• Material waste from bar stock starting point
• Programming and setup complexity
• Estimated baseline cost: Reference

PM 304 SS Approach:

• Near-net-shape from PM process
• Selective grinding of critical features only
• Tooling amortization over production volume
• Estimated cost: 30-40% reduction potential

Key Cost Factors:

• Tooling investment amortized over expected production volume
• Secondary operation requirements (grinding)
• Inspection and quality control
• Production volume assumptions

Cost Note: Actual cost savings depend on specific part geometry, production volume, and supplier capabilities. Figures represent estimated potential based on example application, not guaranteed savings.

Application Results

Performance Characteristics

Dimensional Consistency:

• Statistical process control demonstrated stable process
• Variation lower than machined baseline in comparative study
• Assembly yield improvements noted

Material Properties:

• Non-magnetic requirement met (<1.02 permeability)
• Corrosion resistance suitable for device environment
• Mechanical properties adequate for mounting function

Production Considerations:

• Tooling development time: Standard PM tooling lead time
• Production capacity: Suitable for consumer electronics volumes
• Quality control: 100% inspection of critical dimensions feasible

Observations from Field Use

• Components met optical alignment requirements in assembly
• No field failures attributed to bracket in evaluation period
• Drop test performance acceptable

Performance Note: Results specific to this application. Different designs or requirements may yield different outcomes.

Key Technical Considerations

Achieving Tight Tolerances in PM

Critical Success Factors:

1. Tool Design and Manufacturing
   • Precision tooling fabrication
   • Shrinkage compensation calculations
   • Regular tool maintenance and inspection
2. Process Control
   • Powder characteristics monitoring
   • Compaction pressure control
   • Sintering temperature uniformity and control
3. Secondary Operations
   • Identification of features requiring grinding
   • Precision grinding capabilities
   • In-process inspection
4. Statistical Process Control
   • Regular sampling and measurement
   • Process capability studies
   • Corrective action procedures

Design Guidelines

For Tight-Tolerance PM Parts:

• Minimize tolerance requirements where possible (design for PM)
• Identify critical dimensions requiring secondary operations
• Design for symmetric shrinkage during sintering
• Allow for grinding stock on critical surfaces
• Consider tolerance stack-up in assemblies

Limitations and Considerations

PM Process Limitations

• As-sintered tolerances typically +/-0.1-0.3mm
• Tighter tolerances require secondary operations (grinding)
• Very thin wall sections (<0.5mm) challenging
• Complex internal features may be difficult

Material Considerations

• 304 SS heavier than aluminum (design optimization needed)
• Cannot be hardened by heat treatment (austenitic)
• Magnetic permeability can increase with cold working

Economic Considerations

• Tooling investment requires production volume justification
• Secondary operations add cost (must be factored in)
• Break-even volume depends on complexity and alternatives

Technical Specifications

Component Dimensions (Example)

• Length: 8.5mm
• Width: 6.2mm
• Height: 2.8mm
• Wall thickness: 0.8mm
• Mounting holes: 4x Dia. 1.20mm
• Weight: 0.45g

Material: 304 Stainless Steel PM

• Density: 7.2-7.4 g/cm3 (98% theoretical density)
• Hardness: 75-80 HRB
• Magnetic Permeability: <1.02 (non-magnetic)
• Surface Finish: Ra 0.4 um (ground surfaces)

Manufacturing Recommendations

For Similar Applications

Process Selection:

• PM suitable for medium to high volumes (>50,000 parts typical)
• Machining may be more economical for very low volumes
• Consider total cost including tooling amortization

Quality Requirements:

• Statistical process control implementation
• 100% inspection of critical dimensions feasible
• First article inspection and process validation

Design Approach:

• Design for PM from start when possible
• Identify critical vs non-critical dimensions
• Work with PM manufacturer during design phase

Get Precision PM Components

SinterWorks manufactures precision PM components for electronics and other industries:

• Tight-tolerance support on critical features with secondary finishing when justified
• Non-magnetic materials (304, 316L stainless)
• Precision grinding and finishing capabilities
• High-volume production capability

Note: Tight tolerance capabilities require appropriate secondary operations and process controls. Discuss specific requirements during design phase.

Contact us to discuss your precision component requirements.