🇬🇧 UK Electronics Client | Precision 5-Axis CNC Copper Heat Sink Machining for Industrial Power Modules

Project Background

Thermal Component Prototype for Power Electronics：
In Q4 2024, a UK-based electronics manufacturer specializing in industrial power modules and rail inverter systems reached out to us. They were developing a new high-power rectifier and urgently needed a custom copper heat sink machining solution that ensured tight tolerances, high thermal conductivity, and dimensional stability.
After facing persistent issues—deformation, poor surface finish, and assembly fit errors—from three previous vendors, the client found us via LinkedIn and our website. Our experience in thermal component prototyping, especially in oxygen-free copper machining, gave them the confidence to proceed with a trial order.

Client Requirements

To support the prototype build of their power module, the client specified the following engineering requirements

Material

Part Size

Structure

Tolerance

Surface Finish

Quantity

Lead Time

Documentation

C1100 Oxygen-Free Copper (Thermal conductivity > 390 W/m·K)

~120mm × 85mm × 25mm with multi-layer heat fins

Dense dual-layer cooling fins + flat installation base + dual rail slots

±0.01mm on critical dimensions, surface flatness ≤ 0.03mm

No visible tool marks, raw machined surface only (no polishing)

20 prototypes, 200–300 pieces/month expected in production

12 working days from PO to international shipment

Full English inspection reports, material certs, assembly test photos

Key Technical Challenges

1️⃣ Copper Material Tends to Smear and Burr Easily

C1100 oxygen-free copper is extremely ductile and sticky during cutting, which increases the risk of tool marks, burrs, and built-up edges. Traditional tools wear quickly and generate inconsistent surfaces if not handled correctly.

2️⃣ Tight Tolerances on Finned Structures

The dual-layer heat sink design has over 30 narrow fins with less than 1.2mm spacing. Any deviation in height, parallelism, or burr formation would directly affect thermal performance and component fit.

3️⃣ No Post-Polishing Allowed

To ensure maximum thermal conductivity, the client required the final surface to be “as-machined”—no polishing or surface treatment was allowed, putting full pressure on the raw cutting finish.

4️⃣ Flatness Control of the Base

The bottom surface needed to maintain a flatness tolerance of ≤0.03mm, requiring consistent tool engagement and step-over control across multiple passes without introducing tool-induced waviness.

5️⃣ Short Lead Time + Full Documentation

With only 12 working days from order to international shipment, we had to align programming, tooling, machining, inspection, and packaging in a parallel schedule—all while preparing ISO-compliant English documentation.

Challenges & Solutions

Our Solution

To tackle these challenges, we deployed a comprehensive approach that integrated structural optimization, advanced machining strategies, and efficient project execution

Step 1: Material Preparation & Pre-Treatment

Selected vacuum-annealed C1100 copper blocks with material traceability.
Used wire-cut blanks and fully deburred before CNC operations to minimize burr buildup.

Step 2:CAM Programming & 5-Axis Toolpath Design

· Advanced 5-axis CNC toolpaths programmed in HyperMill
· Ø0.8mm and Ø1.0mm micro end mills used for heat sink fin machining
· Toolpaths optimized for copper deformation control and chip evacuation

Step 3:High-Precision 5-Axis Machining

Machining performed in a temperature-controlled environment (25°C ± 0.5°C).
Used high-pressure micro-mist lubrication to prevent oxidation during machining.
Mirror-finish cutters and slow feed rates were used on base surfaces to ensure flatness.
Every 5 parts prompted tool change to maintain surface consistency.

Step 4:Inspection & Assembly Fit Test

100% CMM inspection on all heat sink fins, alignment grooves, and mounting holes.
Random samples installed into real housing units for fit verification.
Delivered full documentation in English, including:
1.CMM reports (with GD&T data)
2.Material composition certificates
3.Assembly fit photos with explanatory note

Step 5: Protective Packaging

Each part individually placed in custom-cut foam inserts inside kraft cartons.
Clear dual-language labeling with part numbers and PO references.
Photos of packaging sent prior to shipment for client record-keeping.

“Perfect packaging, zero defects. The parts fit just right without any post-processing. We’ve already scheduled the next batch.”

Future Collaboration

This project transitioned into a recurring monthly order, with batch deliveries every two weeks. We’ve also helped the client set up batch traceability templates and inspection routines compatible with their CE and ISO9001 requirements.
Future projects include development of similar modules for a new inverter control platform.

After three successful deliveries with no major quality concerns, client satisfaction remains strong. We’ve since been invited to support two upcoming platform projects, with technical discussions scheduled for next quarter—marking the start of a deeper, long-term collaboration.

The client especially recognized our strengths in

Exceptional surface quality without polishing
Accurate and clean heat sink geometry
Fast response time and organized technical communication
Professional document structure that meets their ISO9001 supplier requirements

Project Summary

This case highlights our ability to deliver complex thermal component prototypes and high-precision copper heat sink machining using 5-axis CNC.
We go beyond being just a machining vendor — we are your technical manufacturing partner for power electronics and high-performance thermal systems.

JoeVin

Joe Vin is the Operations Director at Alec Model, a CNC machining and 3D printing manufacturer in China. With full in-house production and years of hands-on experience, he helps global clients solve real-world manufacturing challenges — from prototyping to production.