Automotive parts and components testing

Tensile tests

(tensile strength, ductility, modulus of tensile elasticity)

The tensile test is one of the basic mechanical tests which, because of its principle, simplicity and effectiveness, is the most widespread and recognized test method for assessing mechanical properties. It consists of placing a smooth test body of a simple shape in the jaws of the test machine, then the dependence of the acting force on the extension of the test body or the dependence of the tension on deformation until a break is experimentally detected by means of a deflection meter deployed on the body.

Bending properties

(bending strength, bending deformation, modulus of flexibility in bending)

The bending properties of polymers are important when polymer parts are strained in bending, which is a very common strain on plastics. Elastomers and lightweight (foam) polymers are generally not rigid enough in bending to carry significant loads, therefore bending tests are rarely or not used with them. For bending tests, prism-shaped housings are used, which are placed on two supports at the prescribed distance. The force applied to the body then acts in the middle between the supports (three-point bend) or is divided into two equal forces acting at a certain distance from the supports (four-point bend). The four-point bend is used for large and thick-walled samples.

Rheological properties

(melt flow index)

The method of determining the flow index of thermoplastic melt is very often used in technical practice for assessing the quality of the input material, for comparing the flow behaviour of melt filled and non-filled thermoplastics, but also for assessing the quality of the production process. The quality of the input material, i.e. its rheological, physical, thermal and other useful properties, is a reflection of the chemical composition of plastic, its molecular structure, etc. The melt flow index gives an idea of the molecular weight and viscosity of the polymer.

The standard for determining the mass (MFR) and volumetric (MVR) melt flow index for thermoplastics specifies two methods for given temperatures and load values, referred to as method A and method B under ISO 1133. The test conditions for measuring the melt flow index are usually specified in the standard for the material, together with a reference to this standard. The weight and volume index of the flow of thermoplastic melt depends on the shear speed or shear tension.

Hardness

(shore hardness, ball hardness)

The value of hardness is an important characteristic of a material. Hardness, as a material-physical property, is generally defined as the resistance of a material against the penetration of a foreign harder body into the measured material. The hardness value gives an idea of the resistance of the material to wear, its workability, the state of heat treatment, etc. Based on the interdependence of the hardness and strength of the material, the strength of the test material can be easily and quickly determined by measuring its strength without lengthy production of a test sample to determine the strength using the test equipment.

Residual fracture energy, Charpy test

Residual fracture energy is a mechanical property that is an integral variable of strength and plasticity. It represents the mechanical energy that is consumed in the plastic deformation of the material. Residual fracture energy is important in terms of stress on structural materials as a mechanical property that describes their resistance to the formation of a fracture.

Flammability of materials

(measurement of burning rate)

Flammability testing is a basic way of determining how easily a material or finished product ignites or burns when placed or used near fire or heat. In fact, the flammability test involves a number of different test protocols and methods aimed at measuring the specific sensitivity of the material including the source of ignition, susceptibility to burning and burning rate. These properties are an important indicator of whether the material or finished product can be safely used without the risk of fire.

Preparation of test bodies

(machining, injection)

Machining is a technological process in which the successive removal of chips produces parts of the required shape, dimensions and quality of the surface.

Plastic injection is one of the main operations in plastic processing. It enables the production of sufficiently precise products from a wide range of plastics in an economically and high-quality manner. Injection products have good accuracy of dimensions and shape.

Identification of material

Infrared spectrometry (FTIR) is a widely used technique for chemical analysis of materials. Because of its considerable simplification and cheaper instrumentation, it is now widely applied to routine applications in industry.
Its advantages include: speed of measurement, financially and environmentally friendly operation, possibility of detection of both organic and inorganic structures at the same time (which can be both amorphous and crystalline in nature), availability of various technological modifications (transmission or reflective equipment), possibility to analyse substances in different states or phases (solid particles, gases, liquids, mixtures, films).

Density

Density measurement is an important parameter for the quality of raw materials and finished products under solid and liquid conditions. It is carried out using various techniques. It determines the purity of the materials before processing, and also whether a substance is mixed with the raw material. On the other hand, density measurement is also effective for understanding of the homogeneity of the raw material.

Filler (ash) content

The purity of the material, the presence of additives and the formation of any ash-forming substance considered as impurities can be assessed from the analysis.

Volatile substances

Gas chromatography (GC) is mainly used in the analysis of gaseous and volatile substances which are converted into gaseous condition by heating without decomposition. For substances which decompose at high temperature or are non-volatile, samples should be transferred using derivatising agents (derivatisation) to volatile derivatives of the analytes prior to analysis. Gas chromatography is a separation method with the possibility of qualitative and quantitative evaluation of the substance under investigation, and we can achieve extremely high sensitivity with a suitable detection device. It is also used for the determination of impurities in the sample.

Water content

The presence of water can significantly affect the quality of the product, its structure, durability, chemical stability and reactivity. One method is Karl Fischer titration, a widely accepted method for measuring water content in all types of substances, including chemicals, oils, medicines and food.

Chemical resistance

Rubber rating

Viscosity, viscosity number

Viscosity is a physical quantity, the degree of resistance of the liquid to deform under the influence of shear (tangential) tensions. It manifests itself in internal friction.

Viscosity indicates the ratio between shear tension and speed change depending on the distances between adjacent layers when actual liquids flow.

The value of viscosity affects: temperature; the rate of deflection; measurement conditions (sample preparation, measuring vessel, appropriate choice of rotary attachment); time; conditions prior to the start of the viscosity measurement; composition of the sample and additives