JIS D4311 Friction and Wear Test of Clutch facings for automobiles

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JIS D4311 Clutch Facings for Automobiles

JIS D4311 Clutch Facings for Automobiles governs wound-type dry friction clutch facings for passenger cars, commercial vehicles, light/heavy-duty trucks and buses (dry clutch only; wet clutch linings are excluded). It covers full lifecycle technical requirements: raw material limit, dimensional tolerance, mechanical performance, friction-wear behavior, hazardous substance control, sampling inspection, marking, packaging, transport and storage.

Inventory of Main Tests Stipulated in JIS D4311

Test Area	Type	Specimen Level
Flatness under specified load	Deflection/gap measurement	Full facing
Friction performance — μ_d(T), allowable deviation Δμ(T), wear rate V(T) across 100→300 °C	Small-sample bench test on constant-speed friction tester	25×25 mm coupons cut from facing
Bending / flexure strength & max strain (3-point bend)	Mechanical destructive	55×15 mm strips cut along friction direction
Rotational burst strength — room temp + 200 °C	High-speed spin rig	6 full facings (3 + 3)

JIS D4311 Friction and Wear Test of Clutch facings for automobiles

Test stipulated in the JIS D4311 details introduction:

1, Flatness Test (Structural Geometry Test)	Whether the annular facing will sit conformally against the pressure plate / flywheel contact plane when a representative clamping-style force is applied.
Test Sample Information	One visually defect-free facing taken from the lot.
Test Equipment	Grade 2 standard flat plate, annular preloading fixture, 0.01 mm precision feeler gauge
Test Procedure	Place lining friction face down on flat plate, apply concentric preload jig; measure 12 circumferential gaps (6 inner, 6 outer at 60° intervals) with feeler gauge; take maximum gap as flatness result
Test Stipulations	Test load: 20 N (≤240 mm OD), 35 N (240–330 mm OD), 50 N (>330 mm OD) Acceptance: Max flatness gap ≤0.25/0.30/0.40 mm by size grade
2, Friction Performance Test (Mechanical Friction-Wear Characteristic Test)	Evaluates the core mechanical function of clutch lining: stable torque transmission and anti-wear capacity under temperature rise during slipping clutch engagement.
Test Stipulation & Acceptance	Dynamic friction coefficient μ_d range: 0.25–0.60 across 100°C~300°C Allowable μ fluctuation: ±0.08 (100°C) up to ±0.14 (300°C) Wear rate limit (V, unit: 10⁻⁷ cm³/(N·m)): 0.50 (100°C) ~ 1.20 (300°C) Post-test requirement: No surface cracks, bulges, or severe scoring on counter steel disc
Test Sample	Cut 2 specimens from one facing, dimension 25 mm × 25 mm (tolerance ±0.2 mm), thickness same as original lining Thickness difference between two specimens <0.2 mm
Test Equipment	Constant-speed friction tester complying with JC/T 1065 0.01 mm precision micrometer P240 abrasive sandpaper for disc surface finishing
Test Procedure	Grind test disc surface with P240 sandpaper to remove scratches/rust; mount two specimens symmetrically Run low-temperature running-in under 0.49 MPa pressure until contact area ≥95%; cool specimens to room temperature and measure average thickness of each piece (5 measuring points per sample) Test sequentially at 100°C, 150°C, 200°C, 250°C, 300°C disc temperature: each temperature stage rotates disc 5000 r, record average friction force f After 300°C high-temperature stage, re-test at 100°C for 3000 r to evaluate friction recovery after thermal load Re-measure specimen thickness after cooling to calculate wear loss
3, Bending Performance Test	Simulates bending deformation stress when clutch disc is pressed by pressure plate during gear shifting; judges material toughness, fiber-matrix bonding integrity and anti-cracking ability.
Test Stipulation & Acceptance	Bending strength ≥35.0 N/mm² Maximum strain ≥10.0 ×10⁻³ mm/mm (ductility indicator)
Test Sample	Cut 3 specimens along the friction winding direction of one lining; avoid grooved areas Standard size: 55 mm ±0.5 mm length ×15 mm ±0.2 mm width; short specimens allowed 40 mm length Specimen thickness equals original clutch lining thickness
Test Equipment & Fixture	Universal Testing machine with bending device with loading speed 10 mm/min, load resolution ≤1 N Standard bending fixture: support span 40 mm (30 mm for short specimens); support head radius R1.5 mm, indenter radius R3 mm
Test Procedure	Measure specimen thickness and width at 3 middle points, calculate average values Adjust fixture support span per specimen length; place specimen friction-side upward on supports Start tester with constant loading rate until specimen fractures; record fracture peak load and maximum deflection δ at breaking moment
4, Rotary Burst Strength Test (Dynamic High-Speed Safety Mechanical Test)	Critical safety test simulating extreme high engine speed (over-revving) where clutch lining bears huge centrifugal force; prevents catastrophic lining fragmentation penetrating transmission housing.
Test Stipulation & Acceptance	Standard reference specimen: 200×134×3.5 mm (no hole, no groove) Room temperature burst speed ≥11,000 r/min 200°C high-temperature burst speed ≥8,000 r/min Angular acceleration fixed at 200 r/(min·s)
Test Sample	6 full intact facings per batch: 3 for room temp test, 3 for 200°C high-temp test
Test Equipment & Fixture	Rotary burst test bench: max speed ≥20,000 r/min, max acceleration ≥300 r/(min·s) Speed error <1%, acceleration error <3%; temperature control chamber (200°C ±2°C) Automatic burst speed recording system, sealed protective rupture chamber
Test Procedure	Empty machine pre-run to calibrate acceleration and speed parameters Mount single lining on matched fixture, lock sealed test cabin Room temperature group: turn off heating, accelerate at 200 r/(min·s) until lining bursts, record rupture RPM High-temperature group: heat specimen to 200°C ±2°C, hold 15 min thermal soak; accelerate with same angular acceleration to burst If specimen reaches equipment top speed without fracture, record upper limit speed and mark "unbroken" Result Rule: Batch burst strength = minimum value among 3 replicate specimens for room/high temperature separately

Why JIS D4311 Is Indispensable for Clutch Friction Materials

Mechanical Safety Assurance (Driven by Mechanical Test Requirements)

Bending test safeguards assembly durability: Clutch linings undergo repeated cyclic bending from pressure plate spring load during every gear shift. The ≥35 N/mm² bending strength threshold eliminates brittle fracture under normal driving cycles; minimum strain standard ensures sufficient flexibility to avoid cracking at cold start or low-temperature operation. Without this standard, low-toughness formulations (excess rigid mineral filler, insufficient organic fiber) would crack prematurely, causing clutch shudder and power loss.

Rotary burst test prevents fatal vehicle failure: At engine over-rev, centrifugal force multiplies exponentially with rotational speed. The standard’s high-temperature burst requirement (8,000 r/min at 200°C) accounts for thermal softening of phenolic resin binder in friction materials during sustained slipping. Unqualified linings will shatter at high RPM, sending sharp fragments to damage transmission, differential or even cabin components, creating severe safety hazards. This mechanical test is a mandatory safety barrier for passenger and commercial vehicles.

Friction mechanical test guarantees consistent power transmission: Dynamic friction coefficient window 0.25–0.60 balances two critical demands: enough friction to transmit full engine torque without slip, and low enough friction for smooth clutch engagement (no harsh jerk). Strict wear rate caps control service life—high wear rate materials lead to frequent clutch disc replacement and increased maintenance cost. Temperature-dependent friction fluctuation limits eliminate thermal fade (drastic μ drop at high heat), a common failure mode causing loss of acceleration during uphill or heavy load.

Quality Supervision & Aftermarket Control

Regulatory authorities use the full test suite (especially mechanical tests) for market spot checks of aftermarket clutch linings. Low-cost counterfeit friction materials usually fail bending strength or rotary burst tests, posing hidden driving risks—this standard provides clear, enforceable technical judgment basis for quality supervision.

Modern high-torque turbocharged vehicles and heavy commercial trucks generate higher thermal and mechanical stress on clutch facings than older models, which drove the 2023 revision to tighten high-temperature friction and burst strength limits.

The three core mechanical tests replicate distinct real service loads:

Bending test = static cyclic compression from clutch pressure plate

Friction test = dynamic slipping friction during gear change and hill start heat accumulation

Rotary burst test = extreme centrifugal load at maximum engine RPM under thermal degradation

Related Standard:

JIS D4411	Clutch facings for automobiles
ISO 26867	Road vehicles - Brake lining friction materials - Friction behaviour assessment for automotive brake systems
ISO 6312	Road vehicles - Brake linings - Shear test procedure for disc brake pad and drum brake shoe assemblies
JC/T 1065	Constant speed friction test machine; Friction-wear performance test
GBT 5764	Clutch facings for automobiles
GBT 5763	Brake linings for automobiles
SAE J661	Brake Lining Quality Test Procedure

Clutch & Brake linging Constant Speed Friction Tester is mainly used to determine the friction properties of slide rails and specific metals at approximate PV values. In addition, the machine can also be used to evaluate the friction and wear performance of lubricants, metals

WDW Series Computer Control Electronic Universal Testing Machine made by UNITEDTEST range from 100N to 600KN load capacity with various models like single columns, table type, door frame type etc., is used to perform tension, compression, flexure/bending, shearing, peeling etc., test for metal and nonmetal specimens.

Three-point bending test fixture for fiber-reinforced plastic composites, designed in accordance with ISO 14125, provides a standardized method for determining the flexural properties of composite materials using a three-point bending test.

Q1: Why is JIS D4311 extremely important for clutch friction materials?

A: Three core reasons:

Vehicle driving safety guarantee: Its three mandatory mechanical tests (bending, rotary burst, friction performance) simulate real extreme working conditions. Unqualified linings may crack under clamping pressure, shatter at high engine speed or lose friction force under high temperature, leading to power failure, transmission damage or traffic accidents.

Unified testing benchmark for industry: Before this standard, manufacturers used self-defined test methods. Now OEMs, friction material factories and third-party labs share identical specimen rules, equipment parameters and calculation formulas to realize comparable product quality data.

Green & regulatory compliance: The 2023 version adds strict hazardous substance limits (asbestos, hexavalent chromium, lead, brominated flame retardants), matching domestic and international automotive environmental requirements, eliminating toxic asbestos linings from the market.

Stable service life control: Restricted wear rate and friction coefficient fluctuation reduce after-sales maintenance costs for vehicle owners and automakers.

Q2: What real vehicle working condition does the bending test simulate? Why is the ≥35.0 N/mm² bending strength mandatory?

A: The bending test simulates repeated cyclic extrusion and bending stress from the clutch pressure plate diaphragm springs during every gear shift.

If bending strength is lower than 35.0 N/mm², the lining will easily crack under long-term clamping load, causing clutch vibration, abnormal noise and torque transmission failure.

The maximum strain index (≥10.0×10⁻³ mm/mm) ensures sufficient material flexibility to avoid brittle fracture under low temperature or frequent shifting.

Specimens are cut along the winding fiber direction to reflect the actual weakest mechanical direction of wound clutch facings.

Q3: What is the purpose of the rotary burst strength test? What risk does it prevent?

A: This test evaluates the lining’s resistance to centrifugal force under extreme high engine RPM, especially when the material softens at high working temperature.

Standard requirement for reference 200×134×3.5 mm lining: ≥11,000 r/min at room temperature, ≥8,000 r/min at 200 °C.

Hidden risk without this test: When drivers over-rev the engine during acceleration or downshifting, centrifugal force will break unqualified linings into sharp fragments. The debris can damage gearboxes, drive shafts and even penetrate vehicle compartments, resulting in serious safety accidents.

The high-temperature test group simulates thermal degradation of phenolic resin binder after long-time clutch slipping during uphill or heavy load transport.

Q4: What does the friction performance mechanical test measure? How does it control driving experience?

A: It measures two core thermo-mechanical indicators: dynamic friction coefficient and wear rate under temperature gradients from 100 °C to 300 °C.

Dynamic friction coefficient range 0.25~0.60 ensures enough friction to fully transmit engine torque without slipping, while avoiding overly aggressive engagement that causes jerky take-off.

Temperature-based allowable friction deviation limits thermal fade (sharp friction drop at high heat), a typical fault of low-quality friction materials.

Graded wear rate limits control service life: excessive wear means frequent clutch disc replacement and increased vehicle maintenance costs.

Post-test visual check forbids cracks or severe scoring on the mating steel disc to protect transmission components.

Q5: When is a full set of mechanical performance tests required for type inspection?

A: Type inspection (covering bending, rotary burst, friction performance plus all other items) must be carried out in the following situations:

New product development, trial production or type approval;

Annual routine inspection during stable mass production;

Raw material formula, production process or core equipment changes that may affect lining mechanical performance;

Production suspended for more than 1 year and restarted;

Factory inspection results show obvious deviation from previous type test data.

Q6: How do friction material manufacturers use mechanical test data under this standard for product development?

A: Formulation engineers rely on the three mechanical test indicators to optimize material formulas:

Increase aramid fiber content to raise bending strength and maximum strain for flexible, crack-resistant linings;

Adjust copper fiber and inorganic filler dosage to improve high-temperature friction stability and rotary burst strength;

Modify phenolic resin binder proportion to reduce high-temperature wear rate while maintaining burst resistance.

All new formula prototypes must pass the full mechanical test suite before mass production approval by vehicle OEMs.

Q7: Can customers customize dimensional or mechanical performance requirements beyond the standard limits?

A: Yes. The standard notes that if purchasers have special working condition demands (e.g., heavy-duty commercial vehicles with ultra-high torque), customized dimensional tolerance, flatness, rotary burst speed or friction coefficient ranges can be agreed via technical contracts between suppliers and buyers. The standard sets baseline minimum mandatory requirements, while special higher indicators are negotiable.

We offer customization to meet your specific needs. Our expert team will collaborate with you to develop the perfect product for you