Table of Contents
Why SinterWorks for Structural PM Parts
We manufacture structural PM hubs, brackets, cams, and bearing housings with DFM support before tooling is released.
- 36 presses from 6T to 400T for prototypes through high-volume programs
- IATF 16949 and ISO 9001 quality systems with PPAP support for automotive programs
- DFM review and quotation feedback within 24–48 hours
- Sizing, steam treatment, machining, and inspection in one workflow
Typical Structural PM Specifications
| Feature | Typical Value | Notes |
|---|---|---|
| Best-fit annual volume | 5,000+ pcs/year | Tooling economics improve above prototype scale |
| As-sintered density | 6.8–7.4 g/cm³ | Grade and compaction dependent |
| Typical tensile strength | 350–750 MPa | FC/FN grades and heat treatment |
| Dimensional tolerance | ±0.05–0.10 mm | Sizing can tighten critical features |
| Sample lead time | 2–3 weeks | After DFM approval and tooling kickoff |
| Production lead time | 4–6 weeks | Volume and finishing dependent |
Common Material Routes
Finishing Options
DFM Guidelines for Structural PM
- Avoid sharp internal corners; use generous fillets to reduce stress and tooling wear.
- Keep uniform wall thickness where possible to control density variation and distortion.
- Define load direction and critical mating surfaces early for material and sizing planning.
- Plan draft and parting lines before locking bracket or housing geometry.
Need a structural PM feasibility review?
Send your drawing, annual volume, and load case. We can recommend material grade, tolerance strategy, and tooling direction.
Introduction
Structural powder metallurgy parts are sintered metal components that carry mechanical load, transmit force, or provide positional reference in an assembly. They are not simply shaped metal — they must meet dimensional, strength, and surface requirements that allow them to function reliably across the expected service life.
PM is well-suited to structural parts because the process produces near-net-shape components with consistent density and geometry across high production volumes. Parts that would require significant machining from bar stock are often produced more cost-effectively through die compaction and sintering.
Request a DFM review and quotation if you have drawings and a volume target.
Common Structural PM Part Types
Hubs and Flanges
Hubs and flanges are among the most common PM structural parts. The process accommodates the cross-sectional variation (hub boss, flange disc, central bore) in a single pressing operation, with controlled density in each section.
Typical applications:
- Synchronizer hubs (transmission and driveline)
- Clutch hubs and carrier plates
- Flange couplings for shaft connections
- Sprocket hubs and drive flanges
Design notes: Hub height-to-diameter ratios up to approximately 2.5:1 are typical. Multiple levels (boss, flange, shoulder) require multi-action tooling but are standard PM practice.
Brackets and Structural Supports
PM brackets and supports provide mounting surfaces, spacer functions, or structural bridges in assemblies. They compete most directly with die castings and stamped-and-welded fabrications.
Typical applications:
- Sensor mounting brackets
- Bearing support housings
- Motor end caps and brush holders
- Structural spacers in precision assemblies
PM advantage over die casting: Tighter dimensional tolerances as-sintered, no porosity-related leak paths for oil or grease interfaces, and faster production cycle time.
PM advantage over stamped fabrications: Complex 3D cross-sections achievable without secondary forming or welding.
Cam Lobes and Eccentric Parts
Cam lobes and eccentric elements require precise profile geometry, controlled hardness on the working surface, and repeatable dimensions across production batches.
Typical applications:
- Automotive camshaft lobes (assembled camshaft design)
- Eccentric cams for pump and valve actuation
- Indexing cams for automation equipment
- Textile machinery cams
Materials: FC-0208 and sinter-hardened alloys are common for cam lobes requiring surface hardness HRC 30–50. Heat treatment after sintering is an option for grades that require it.
Bearing Housings and Seats
Bearing housings and seats require a controlled bore for bearing press-fit, precise OD for housing location, and adequate structural rigidity to resist deflection under load.
Typical applications:
- Electric motor end shields
- Gearbox and reducer bearing housings
- Agricultural and industrial bearing blocks
- Pump and compressor bearing supports
PM advantage: Die-compacted bore and OD are close to net-shape; sizing (secondary compaction) corrects bore and OD to tight tolerance without full machining.
See also: Oil-Impregnated Bearings if the application requires a self-lubricating PM bearing rather than a housing.
Ratchet and Pawl Components
Ratchet wheels, pawls, and locking elements require controlled tooth geometry, adequate surface hardness, and precise bore or shaft interface.
Typical applications:
- Seat recliner mechanisms
- Window regulator ratchet components
- Lifting and locking mechanisms
- Power tool clutch elements
Connecting and Transmission Parts
Connecting rods, push rods, shift forks, and linkage elements are structural PM parts that transmit force under dynamic or cyclic loading.
Typical applications:
- Powder metal connecting rods (fracture-split design)
- Shift forks for transmission and transfer case
- Push rods and lifter bodies
- Suspension linkage components
Materials: FN-0205, FN-0405, and sinter-hardened grades for fatigue-critical connecting and transmission components.
Material Selection for Structural PM Parts
| Material | Tensile Strength (typical) | Best Use |
|---|---|---|
| FC-0205 | 400–550 MPa | Light-to-moderate load brackets, housings |
| FC-0208 | 550–750 MPa (heat-treated: to 900 MPa) | Cams, hubs, gear blanks — hardenable |
| FN-0205 | 500–700 MPa | Tough transmission and drivetrain parts |
| FN-0405 | 700–950 MPa | High-strength gears, connecting rods |
| Sinter-Hardened | 700–1,000 MPa | Surface-critical cams, followers |
| Copper-Infiltrated | 700–900 MPa | High-density load-bearing parts, low porosity |
| 316L Stainless | 480–650 MPa | Corrosion-resistant structural components |
See the Materials Guide for complete data tables, heat treatment options, and material comparison charts.
Tolerances and Secondary Operations
As-sintered dimensional capability (typical, non-critical cross-sections):
- OD/bore: ±0.10–0.20 mm
- Length / height: ±0.15–0.25 mm
- Flatness: 0.10–0.20 mm
After sizing (secondary compaction to calibrate dimensions):
- Bore / OD: ±0.025–0.05 mm
- Length (if sized): ±0.05–0.10 mm
After CNC machining (for critical features: threads, precision bores, ground surfaces):
- Achievable to ±0.01–0.02 mm on machined features
Secondary operations available: CNC turning and milling, thread tapping, broaching, grinding, heat treatment, surface treatment (zinc phosphate, steam, plating, passivation).
See Secondary Machining and Surface Treatments for details.
PM vs Alternatives for Structural Parts
| Criterion | PM | Die Casting | Machined Bar Stock | Forgings |
|---|---|---|---|---|
| Tooling cost | Medium | Medium–High | None | High |
| Unit cost at 25K pcs | Low–Medium | Low–Medium | High | High |
| Material density | 85–95% | ~100% | 100% | 100% |
| Dimensional consistency | High | Medium | High (machined) | Medium |
| Design complexity | Medium | High | Low–Medium | Low |
| Lead time (samples) | 4–8 weeks | 6–10 weeks | 1–2 weeks | 8–12 weeks |
| Secondary machining | Low–Medium | Medium | High | Medium |
For a detailed comparison, see: PM vs Die Casting, PM vs Forging, PM vs Machined Bar Stock.
Quality and Documentation
Our structural PM parts are produced under IATF 16949:2016 and ISO 9001:2015 quality systems. Standard documentation includes:
- First article dimensional reports
- Material certifications (chemistry, hardness)
- Process qualification records
- PPAP package support (for automotive programs)
See PPAP Support and Quality Inspection for details.
Frequently Asked Questions
What is the minimum production volume for structural PM parts?
PM tooling investment makes the process most economical above 5,000 parts per year. Below that threshold, machined bar stock or casting may have lower total cost. At 10,000+ parts per year, PM typically offers a clear cost advantage over machined alternatives.
Can PM structural parts handle impact loading?
Standard PM grades (FC-0205, FC-0208) have limited ductility and are not ideal for high-impact applications. For impact-tolerant structural PM, nickel-steel grades (FN-0205, FN-0405) or heat-treated sinter-hardened alloys provide better toughness. For very high impact, forging or wrought material may be more appropriate.
How are critical bore tolerances held in PM structural parts?
Bore tolerances are controlled by sizing — a secondary compaction step that compresses the sintered part in a precision die to calibrate bore and OD dimensions. Sizing can hold bore tolerances to ±0.025–0.05 mm without full machining.
What surface treatments are available for structural PM parts?
Common options: zinc phosphate (corrosion protection + paint adhesion), steam treatment (improved hardness and mild corrosion resistance), zinc plating, nickel plating, and carburizing or through-hardening for wear surfaces. See Surface Treatments for a complete overview.
Can PM structural parts be welded or joined to other components?
PM parts can be joined by press-fit, brazing, and adhesive bonding. Fusion welding is more difficult due to porosity and variable density; it is done in some applications but requires process development. Consult engineering before specifying a welded PM assembly.
Related Resources
Use these internal links to keep moving through the most relevant guides, service pages, and technical references for this topic.
Automotive PM Parts
Structural PM in transmission, engine, and chassis programs at automotive quality standards.
Materials Guide
Compare FC, FN, and other structural PM material grades for load and fatigue requirements.
DFM Guide
Design-for-manufacturability rules for structural PM parts before tooling is committed.
Request a Quote
Send drawings and volume targets for structural PM DFM review and pricing.