Material property testing verifies how the materials in a part behave under mechanical and environmental conditions, providing data for material selection and supplier evaluation. Beyond strength, automotive materials must account for the combined effect of temperature, humidity and ageing.
Common mechanical tests
Tensile properties: yield strength, tensile strength, elongation at break.
Flexural properties: flexural strength, flexural modulus.
Impact properties: notched and unnotched impact, used to assess the tendency to brittle fracture.
Hardness: Shore, Rockwell, Barcol (common for sheet materials).
Compression properties: often used to assess compression set of seals and structural parts.
Flammability evaluation
UL94 rating: V-0 / V-1 / V-2 / HB, the most widely used plastics flammability classification.
Limiting oxygen index (LOI): the minimum oxygen concentration that sustains combustion; higher values mean the material is harder to burn.
Cone calorimetry (CONE): measures heat release rate and total heat release, assessing fire hazard.
Glow-wire temperature (GWE) and glow-wire ball test (GWBT): reproduce heat resistance in electrical fire scenarios.
Temperature effects
Material properties change markedly with temperature: strength drops when hot and the material becomes brittle when cold.
Reference standards: GB/T 1040 (tensile), GB/T 1043 (flexural), GB/T 16422 (property retention after ageing).
Automotive parts are often tested separately at low temperature (-40 C) and at high temperature (85 C / 105 C).
Property retention after damp heat ageing is a key indicator of long-term material stability.
Evaluation after the test
Compare with the initial value to calculate property retention.
Fracture analysis: observe fracture morphology by SEM to determine ductile or brittle failure.
Flammability classification: grade according to the phenomena the standard specifies, such as dripping and whether extinction time is met.
Dimensional change: shrinkage or expansion after ageing, which affects assembly fit.
Frequently asked questions
Why do different batches of the same material perform so differently?
The usual causes are incoming material control and process stability. Worth checking: whether the supplier fixes production batches, whether incoming inspection records exist, whether key parameters (ash content, moisture, melt index) are within specification, and whether storage conditions are controlled. The consistency of results across multiple submissions from the same supplier is also an important indicator of supplier stability.
What does a V-0 flammability rating require?
UL94 V-0 requires the specimen not to continue burning for more than 5 seconds after the flame is removed, not to re-ignite within 1 second, and not to drip flaming material that ignites the marker. Material thickness also affects the rating, so testing must use the thickness actually used in the part.
Service notes
Our laboratory holds both CMA and CNAS accreditation, covers about 10,000 m2 and runs more than 500 sets of equipment. All testing is carried out in our own laboratories — nothing is subcontracted. Plant visits and on-site witnessed testing are welcome.
Scheduling follows the actual project pipeline. You can state your preferred lead time when you submit samples; we will confirm a feasible plan against current capacity and keep you updated at each milestone. Once the report is issued we send the electronic copy; corrective-action advice can be arranged separately.
