Brake Disc/Rotor: Thickness 20-40mm, Parallelism 0.01-0.02mm

Component Specifications

Definition

The brake disc, also known as a rotor, is a critical rotating component in disc brake systems that works in conjunction with brake pads. When hydraulic pressure is applied, the brake pads clamp onto both sides of the disc, creating friction that converts the vehicle's kinetic energy into heat energy, thereby decelerating or stopping the wheel rotation. Modern brake discs feature ventilation channels, slots, or drilled holes to enhance heat dissipation and improve braking performance under various conditions.

Working Principle

The brake disc operates on the principle of friction-based energy conversion. When the brake pedal is depressed, hydraulic pressure forces brake calipers to squeeze brake pads against the rotating disc surfaces. The resulting friction generates heat, dissipating the vehicle's kinetic energy and reducing rotational speed. The disc's rotational motion ensures even wear distribution and consistent braking force application.

Materials

Typically manufactured from cast iron (gray iron, ductile iron), carbon steel, or composite materials. High-performance applications may use carbon-ceramic composites, reinforced aluminum alloys, or surface-treated steels with coatings like zinc, phosphate, or ceramic for corrosion resistance and enhanced thermal properties.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Weight	5-15kg depending on size
Diameter	200-400mm (passenger vehicles)
Hardness	180-240 HB (cast iron)
Thickness	20-40mm
Parallelism	0.01-0.02mm
Runout Tolerance	0.05-0.10mm
Minimum Thickness	Specified by manufacturer (typically 1-2mm less than new)
Surface Roughness	Ra 1.6-3.2μm

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 15484, ISO 26262, DIN 75078, SAE J431, ECE R90

Parent Products

This component is used in the following industrial products

Brake/Locking Mechanism

A mechanical or electromechanical device that stops or holds an indexing mechanism in a fixed position.

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Braking Mechanism

A mechanical or electromechanical device within a positioning system that controls deceleration, stops movement, or holds position.

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Engineering Analysis

Risks & Mitigation

Thermal cracking from overheating
Corrosion leading to reduced friction
Runout causing vibration/pulsation
Premature wear from contaminated surfaces
Material fatigue under cyclic stress

FMEA Triads

Trigger: Excessive heat generation during prolonged braking
Failure: Thermal cracking and warping
Mitigation: Use ventilated discs, proper cooling designs, heat-resistant materials, and driver education on braking techniques

Trigger: Corrosive environment exposure
Failure: Surface pitting and reduced friction coefficient
Mitigation: Apply protective coatings, use corrosion-resistant alloys, implement regular inspection protocols

Trigger: Improper installation torque
Failure: Uneven mounting leading to runout and vibration
Mitigation: Follow manufacturer torque specifications, use calibrated tools, implement installation training

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

Diameter tolerance ±0.5mm, thickness variation ≤0.015mm, runout ≤0.10mm, parallelism ≤0.02mm

Test Method

Dimensional verification with micrometers and dial indicators, hardness testing (Brinell/Rockwell), metallurgical analysis, dynamometer testing for friction performance, salt spray testing for corrosion resistance, thermal cycling tests

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

Check the legal entity, factory address, ownership, certifications, and direct contacts.

CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Brake Disc/Rotor

Manufacturer profiles associated with Brake Disc/Rotor.

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Related Components

Brake Disc (Rotor)

A rotating disc in disc brake systems that creates friction with brake pads to slow or stop vehicle motion.

Main Bearing Journals

Main bearing journals are precision-machined cylindrical surfaces on a crankshaft that rotate within main bearings to support rotational motion in internal combustion engines.

Surround

Structural component that encloses and protects suspension system elements while providing mounting points and structural integrity.

Wrist Pin (Piston Pin)

A precision cylindrical pin connecting the piston to the connecting rod in reciprocating engines.

Frequently Asked Questions

How often should brake discs be replaced?

Brake discs typically last 50,000-70,000 miles but require replacement when worn beyond minimum thickness specifications, show severe scoring, cracking, or excessive runout. Always follow manufacturer recommendations and inspect during brake pad changes.

What causes brake disc warping?

Disc warping results from uneven heat distribution during aggressive braking, improper torque during installation, material inconsistencies, or rapid cooling (like driving through water when discs are hot). Proper bedding-in procedures and avoiding extreme thermal stress can prevent warping.

What's the difference between solid and ventilated brake discs?

Solid discs are single-piece designs for lighter vehicles; ventilated discs have internal vanes between friction surfaces to create airflow, significantly improving heat dissipation for heavier vehicles or performance applications.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Brake Disc/Rotor