Problem
Machining problem to solve
Complex automotive part geometryTight tolerance controlStable batch production
Case Study
Automotive Case Study 10 / 20Brake Disc Machining Case Study
The brake disc, also known as the brake rotor, is one of the most critical safety components in an automotive braking system.
brake disc machining case studyautomotive cnc machining case studycnc machine for automotive parts
Case Overview
Core project data for this machining case.
Industry Automotive
Product Brake Disc / Brake Rotor
Material Gray Cast Iron HT250 / High Carbon Cast Iron / Carbon Ceramic
Process Casting + Heat Treatment + CNC Machining
Machine Model HYR VMC850
Tolerance +/-0.015 mm
Surface Finish Ra0.8
Production Capacity Project based
Solution
HYR-CNC machining plan
The customer is a brake system manufacturer supplying:Passenger vehiclesElectric vehiclesSUVsLuxury sedansHigh-performance sports cars
Machine Used
Recommended machine configuration
Machine: HYR CNC machining center selected according to part size, material and tolerance
Process: Rough machining, semi-finishing, finish machining and inspection based on the document case
Accuracy Control: Fixture planning, deformation control, stable toolpath strategy and CMM inspection
Cost Method: Published with existing website assets first to keep implementation cost low
Process
Timeline from raw material to inspection.
01 Typical manufacturing process:
02 Casting
03 Heat Treatment
04 Shot Blasting
Full Case Article
Machining background, difficulty and solution logic.
Quick Facts
Item Details Industry Automotive Product Brake Disc / Brake Rotor Material Gray Cast Iron HT250 / High Carbon Cast Iron / Carbon Ceramic Manufacturing Process Casting + Heat Treatment + CNC Machining Machine HYR VMC850 Tolerance +/-0.015 mm Disc Thickness Variation ≤0.01 mm Surface Finish Ra0.8 Application Passenger Cars, EVs, SUVs, Performance Vehicles
Introduction
The brake disc, also known as the brake rotor, is one of the most critical safety components in an automotive braking system.
Its primary function is to convert the vehicle's kinetic energy into thermal energy through friction generated between:
During emergency braking, the surface temperature of the brake disc may exceed:
Therefore, brake discs require:
Although casting creates the overall geometry, precision CNC machining determines the final braking performance and driving safety.
Brake disc and Brake pads 500 degreesC ↓ 800 degreesC Excellent heat dissipation High dimensional stability Superior wear resistance Stable friction performance Precise dynamic balance
Customer Background
The customer is a brake system manufacturer supplying:
Their brake disc products include:
The customer faced several issues:
HYR CNC developed a machining solution optimized for high-speed brake disc production.
Passenger vehicles Electric vehicles SUVs Luxury sedans High-performance sports cars Solid brake discs Ventilated brake discs Drilled brake discs Slotted brake discs Carbon ceramic brake rotors Friction surface waviness Disc thickness variation Dynamic imbalance Tool wear during cast iron machining Inconsistent surface finish
Industry Background
The braking industry is evolving rapidly.
Electric Vehicles Require Better Braking
EVs are generally:
Brake discs must therefore provide:
Heavier Faster Equipped with regenerative braking Better corrosion resistance Improved thermal stability Lower vibration
High-Performance Brake Systems
Modern vehicles increasingly adopt:
These designs improve:
But they significantly increase machining complexity.
Larger brake rotors Ventilated discs Cross-drilled designs Carbon ceramic discs Heat dissipation Braking force High-speed stability
NVH Requirements
Brake noise and vibration are major concerns.
Requirements include:
Machining accuracy directly affects NVH performance.
Better flatness Lower runout Superior balancing
Gray Cast Iron HT250
HT250 is the most widely used material.
Advantages:
Applications:
Excellent damping Good thermal conductivity Stable friction coefficient Passenger cars SUVs EVs
High Carbon Cast Iron
Advantages:
Applications:
Better heat resistance Reduced thermal cracking Lower brake noise Luxury vehicles Performance vehicles
Carbon Ceramic
Advantages:
Applications:
Extremely lightweight Excellent heat resistance Outstanding wear resistance Supercars Racing cars Premium EVs
Manufacturing Process
Typical manufacturing process:
Among all operations, finish machining determines braking performance.
Casting ↓ Heat Treatment ↓ Shot Blasting ↓ Dynamic Balance Pre-Test ↓ Rough Turning ↓ Rough Milling ↓ Finish Machining ↓ Friction Surface Machining ↓ Hole Machining ↓ Dynamic Balancing ↓ Inspection ↓ Packaging
Why CNC Machining Is Necessary
Brake discs operate under extremely demanding conditions.
Casting alone cannot meet final requirements.
Friction Surface Accuracy
The friction surface requires:
Poor machining may cause:
Surface Finish Ra0.8 Flatness ≤0.015 mm Brake noise Uneven pad wear Brake judder
Disc Thickness Variation
A critical parameter:
Excessive DTV causes:
DTV Disc Thickness Variation ≤0.01 mm Steering wheel vibration Pulsating brake pedal Reduced braking comfort
Dynamic Balance
At high speed:
Brake discs rotate at high RPM.
Requirements:
Poor balancing causes:
150 km/h ↓ 250 km/h Dynamic Balance ≤5 g·cm Vibration Noise Bearing wear
1. High Hardness Cast Iron
Typical hardness:
Challenges:
Stable spindle power is required.
HB180 ↓ HB240 High tool wear Heat generation Chipping
2. Large Diameter Components
Typical diameter:
Challenges:
260 mm ↓ 420 mm Dynamic balance Surface waviness Flatness control
3. Surface Finish
The friction surface requires:
Any defects may affect:
Ra0.8 or better Braking comfort Noise level Heat generation
HYR CNC Solution
HYR recommended the VMC850 Vertical Machining Center.
High-Speed Spindle
Spindle:
Advantages:
BT40 12000 rpm Stable cast iron machining Better surface finish Reduced vibration
High Rigidity Structure
Features:
Benefits:
Heavy cast iron base Reinforced column Wide-span guideways Better flatness Improved surface quality Reduced chatter
Precision Linear Guideways
Advantages:
Suitable for:
High repeatability Stable positioning Smooth movement Friction surfaces Bolt holes Balancing features
Automatic Tool Changer
24-tool ATC.
Supports:
Improving machining efficiency.
Face milling Drilling Chamfering Counterboring
Step 1
Machine:
Remove casting allowance.
Rough Machining Outer diameter Reference surfaces
Step 2
Machine:
Prepare for finishing.
Semi Finishing Mounting faces Ventilation structures
Step 3
Machine:
Requirement:
Friction Surface Machining Inner friction face Outer friction face Ra0.8
Step 4
Machine:
Bolt Hole Machining Wheel bolt holes Center bore Balance holes
Step 5
Adjust:
Requirement:
Dynamic Balancing Weight distribution Rotational balance ≤5 g·cm
Step 6
Remove:
Improve assembly safety.
Deburring Burrs Sharp edges
Step 7
Inspect:
Guarantee braking quality.
Final Inspection Flatness Surface finish Thickness variation Dynamic balance
Cutting Parameters
Typical machining parameters:
Item Value Spindle Speed 8000 rpm Feed Rate 1800 mm/min Tool Material Carbide Coolant Dry / MQL Depth of Cut 0.4 mm Surface Finish Ra0.8
Quality Inspection
Every brake disc undergoes strict inspection.
Friction Surface Inspection
Requirement:
Inspect:
Ra0.8 Roughness Flatness Surface waviness
Thickness Variation
Requirement:
Inspect:
≤0.01 mm Disc thickness Parallelism
Dynamic Balance
Requirement:
Inspect:
≤5 g·cm Mass distribution Rotation stability
CMM Inspection
Verify:
Ensuring complete dimensional accuracy.
Bolt hole positions Center bore Geometric tolerances
Results
After adopting HYR CNC machining solutions:
The customer achieved:
Item Before After Surface Finish Ra1.6 Ra0.8 DTV 0.03 mm 0.01 mm Dynamic Balance 12 g·cm 4 g·cm Cycle Time 18 min 12 min Scrap Rate 2.5% 0.3% Better braking comfort Lower brake noise Improved thermal stability Higher production efficiency Reduced manufacturing costs
HYR VMC850
Recommended for:
Brake Discs Brake Calipers Steering Knuckles
HYR VMC1060
Suitable for:
Control Arms Suspension Components Structural Parts
HYR VMC1165
Ideal for:
Subframes E-Axle Housings Large EV Structures
Related Articles
What Is Surface Finish?
What Is CNC Milling?
Brake Caliper Machining Case Study Steering Knuckle Machining Case Study Cast Iron Machining Guide
What materials are commonly used for brake discs?
Gray cast iron HT250, high carbon cast iron and carbon ceramic materials are widely used.
Why is CNC machining necessary?
Critical features such as friction surfaces, bolt holes and balancing structures require precision machining beyond casting capabilities.
What surface finish is required?
Most brake discs require friction surface roughness of Ra0.8 or better.
What is DTV?
DTV stands for Disc Thickness Variation, which measures thickness consistency across the brake rotor.
Which CNC machine is suitable?
The HYR VMC850 is an excellent solution for precision machining of brake discs and braking system components.
Conclusion
Brake discs are among the most important safety components in modern vehicles.
From friction surfaces and bolt holes to dynamic balancing and thermal stability, machining precision directly affects braking performance, comfort and safety.
With high rigidity, excellent cast iron machining capability and stable surface quality, HYR CNC machining centers provide reliable and efficient solutions for brake disc manufacturing.
HYR CNC continues to support global automotive manufacturers with advanced machining technology and customized braking system production solutions.
Result
Before and after machining improvement.
| Item | Before | After |
|---|---|---|
| Result 1 | Before optimization | After adopting HYR CNC machining solutions: |
| Result 2 | Before optimization | Item |
| Result 3 | Before optimization | Before |
FAQ
Common buyer questions for this case.
What is this case about?
This article covers brake disc / brake rotor machining requirements, challenges, process planning and CNC machine selection.
Which machine is recommended?
The final machine should be selected according to part size, material, tolerance, cycle time and fixture plan.
Can HYR-CNC support similar parts?
Yes. Send drawings, material, tolerance and volume so HYR-CNC can recommend a suitable machining proposal.
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