Custom CNC Machining Aluminum Pulleys
Lightweight, high‑strength engine belt pulleys — machined from solid aluminum for automotive, racing, and industrial applications.
- CNC turned & milled
- Tolerances ±0.02 mm
- V‑belt / multi‑rib / timing
- In-house anodizing
Why CNC for Aluminum Pulleys?
An engine pulley isn’t just a wheel — it’s a precision component that must maintain belt alignment, balance, and runout at high RPM. CNC machining delivers the accuracy and consistency that cast or stamped pulleys can’t match.
- Groove accuracy — V‑grooves, multi‑rib (PK), and timing profiles machined to ±0.01 mm for zero belt slip
- Integrated features — keyways, set‑screw holes, flanges, and timing marks in one setup
- Lightweighting — 6061 / 7075 aluminum reduces rotational mass by 40‑60% vs steel
- No tooling — perfect for prototypes, racing runs, and low‑volume OEM
Typical Specifications
| Material | 6061‑T6 · 7075‑T6 · 2024‑T3 |
| Bore tolerance | ±0.01 mm (H7 or custom) |
| Groove profile | V‑belt (A/B/SPA/SPB) · multi‑rib (PK) · timing |
| Runout (TIR) | ≤ 0.02 mm |
| Dynamic balance | G2.5 or better @ operating RPM |
| Surface finish | Ra ≤ 0.8 μm (groove faces) |
| Anodizing | Clear · black · hard coat (Type III) |
Aluminum Alloys for Pulleys
Select the right alloy for your application — balancing strength, weight, machinability, and cost.
6061‑T6
Standard choice
Excellent machinability, good corrosion resistance, and cost‑effective. Widely used for OEM and aftermarket pulleys.
- Great for daily driver & mild performance
- Takes anodizing well
- Easy to machine — lower cost
7075‑T6
High‑strength
Nearly twice the tensile strength of 6061. Ideal for racing, high‑RPM, and heavy‑load applications where weight is critical.
- Superior fatigue resistance
- Best strength‑to‑weight ratio
- Premium performance builds
2024‑T3
Aerospace grade
High fatigue strength and good machinability. Used in extreme applications where both strength and light weight are required.
- Excellent fatigue properties
- Higher copper content — stronger
- Requires anodizing for corrosion protection
Manufacturing Process
From aluminum bar stock to a finished, balanced pulley — each stage is controlled for precision and repeatability.
CNC Turning (OD / ID)
Rough and finish turning of outer diameter, bore, and face. Single‑setup turning ensures bore‑to‑OD concentricity.
- ±0.01 mm bore · H7 fit
Groove Milling & Profiling
Precision milling of V‑grooves, multi‑rib profiles, or timing teeth. CNC‑controlled form tools ensure consistent belt engagement.
- Ra ≤ 0.8 μm · profile accuracy
Balancing & Finishing
Dynamic balancing, deburring, keyway broaching, and surface finishing. Hard anodizing available for wear resistance.
- G2.5 balanced · anodized
- Post‑processing: Clear anodizing, hard anodizing (Type III), black anodizing, and light bead blasting.
Speed Meets Precision at MachMaster
See our team, process, and precision in action at Xiamen MachMaster Co., Ltd—where every part is backed by expertise, systems, and measurable results.
Design Considerations
for Pulleys
Key design parameters our engineering team reviews to ensure manufacturability and performance.
Groove Profile & Finish
V‑grooves and multi‑rib profiles must match belt specs precisely. We machine to ANSI / ISO standards with Ra ≤ 0.8 μm on contact faces.
Bore & Keyway Fit
Specify H7 or custom bore tolerance. Keyways must be positioned accurately — we hold ±0.02 mm for keyway location relative to grooves.
Wall Thickness & Weight
Thin sections reduce inertia but can cause chatter. We recommend minimum 3‑4 mm wall thickness for structural integrity during machining.
Anodizing Considerations
Hard anodizing (Type III) adds wear resistance but changes dimensions by 0.02‑0.05 mm — account for this in your tolerance stack.
Applications
CNC machined aluminum pulleys are used across automotive, racing, and industrial sectors.
- Crankshaft pulleys
- Water pump pulleys
- Alternator pulleys
- Power steering pulleys
- Idler pulleys
- Tensioner pulleys
- Racing & performance
- Heavy‑duty / commercial
- Motorcycle pulleys
- Industrial belt drives
- Custom aftermarket
Ready to Machine Your Pulley?
Upload your CAD, specify material and groove profile. We’ll review, balance the design for manufacturability, and quote within 24 hours.
- No MOQ
- No tooling costs
- Free DFM review
