Testing

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Testing of Material and Component

Today, elastomers are used in almost all industrial applications and yet they remain a mystery to many users. Classical laws from metallurgy do not usually apply to elastomers and their particular characteristics cannot be understood with chemistry alone. Therefore, materials testing has become an indispensable tool for rubber parts over the past decades.

Depending on the objective, we test and examine your products and materials with regard to different criteria. These include the determination of different material and component properties, tests in accordance with institute specifications, national and international standards or factory standards as well as special functionality and compatibility tests.

Material Testing

An Indispensable Tool

When a product fails unexpectedly, experience has shown that in almost every case the problem can be traced back to lack of, or inadequate, testing, which in turn resulted from an attempt to save money.

Roger BROWNPhysical Testing of Rubber, Springer, New York, 4. Edition 2006

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In the DICHT! special edition O-Ring Prüflabor Richter you will find a comprehensive overview of common tests and analysis methods in elastomer technology. Discover the collected knowledge about elastomer testing in this issue. This special edition is in German.

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Tests and Testing Criteria

What is tested and how is it done

In addition to the basic properties and performance of materials under certain conditions of use, the structure of polymers and their ingredients can also be tested. Furthermore, the compatibility of the materials in contact with different substances and the ageing behaviour are tested. The tests and examinations offered by the Elastomer Institute Richter can be broken down into five criteria:

Material properties
Formulations and substances
Function and compatibility
Conformity in accordance with specifications
Component testing

Tests by Objectives

Material Properties Formulations and Substances Function and Compatibility Conformity to Specification Components and Characteristics

Testing of Material Properties

Basic Properties • Material Performance • Ageing and Resistance

The testing of material properties provides a basic understanding of a material. They make it possible to evaluate the materials, to compare them with other compounds and to estimate the material performance when used in technical applications.

Basic Properties

Examinations of these essential material properties provide fundamental information about elastomers and allow conclusions to be drawn about the structure, identity, quality and suitability of an elastomer for the intended use.

Furthermore, analyses of these properties are useful for the comparison of different elastomer compounds with each other. For a reliable evaluation of materials and compounds, it is usually necessary to test several basic properties. Of course, this also depends on the respective load.

Basic Properties

Hardness

Hardness provides information about the deformation behaviour of materials. Along with other material parameters, it allows formulations to be identified. Besides the determination of density and component dimensions, hardness measurement is one of the three most important components of an identity check.

Basic Properties

Density

Density is a characteristic material property and is independent of the shape and size of a body. This material constant describes the mass of a body relative to its volume. Along with the determination of hardness and component dimensions, the density test is one of the three most important components of an identity test.

Basic Properties

Tension Set

Elastomers mainly deform elastically under load, which means reversibly, but to a certain extent they also deform permanently. The tension set (TS), similar to the compression set (CS), provides information about the resilience behaviour of elastomers under temperature load.

Basic Properties

Compression Set

Elastomers are not ideal elastic materials. If a component made of elastomer material is deformed for a long time, it does not completely return to its original shape after the stress has been released. The compression set is a measure of this permanent part of the deformation.

Basic Properties

Tensile Strength, Tear Resistance and Elongation at Break

Tensile strength, tear resistance and elongation at break are characteristic values of elastomers and provide information about the mechanical load capacity of a material and its cross-linking density. They are determined using the tensile test.

Basic Properties

Tear Propagation Resistance

The tear propagation resistance, also called tear propagation strength, shows how quickly a rubber material fully cracks after an initial tearing. This value is often used as a criterion for selecting materials for rubber components that are subject to high physical loads.

Basic Properties

Compressive Stress Relaxation

Based on the determined compressive stress relaxation, the relaxation behaviour, which means the decrease of tension under load and performance of sealing materials, can be shown.

Material Performance

Elastic, Thermic, Electrical

Examinations of the viscoelasticity and the flow and relaxation characteristics of rubber materials during deformation or under temperature load allow for conclusions to be drawn about their processing quality and the suitability of components for technical applications.

Information on the electrical properties is particularly important for the electrotechnical use of components, for example in energy technology, building technology or sensor technology.

Analytics, Material behavior

Dynamic Mechanical Analysis (DMA)

In dynamic mechanical analysis (DMA), sometimes also called dynamic mechanical thermal analysis (DTMA), the dynamic mechanical properties of elastomers are qualitatively and quantitatively determined under various conditions.

Material behavior

Rebound Resilience

Rebound resilience shows the elastic behaviour of elastomers when subject an impact load. It shows the suitability of a material for vibration-related tasks and is dependent on the material type, the material formulation and the test temperature.

Material behavior

TR10 Value

The mechanical and elastic properties of elastomers change with temperature. The TR10 value (Temperature Retraction) describes the resilience of elastomers in cold conditions and identifies the temperature at which a frozen, stretched elastomer sample has deformed back by 10%.

Material behavior

Compression set at low temperatures

The compression set at low temperatures is simply the acid test for sealing materials. What is left of the material's resilience in the cold? The determination of the CS at low temperatures provides information about the behaviour of the materials during cooling and the preservation of their elasticity.

Analytics, Material behavior

Differential Scanning Calorimetry (DSC)

In the elastomer sector, DSC analysis is often used to determine the glass transition temperature. In addition, it offers the possibility of detecting residual amounts of cross-linking agent in the elastomer and thus allows conclusions to be drawn about the degree of cross-linking of a material.

Material behavior

Electrical Properties of Elastomers

Resistivity and potential difference measurements provide information about the electrical properties of elastomers. They help to assess the behaviour of the components in use and the risks of electrostatic charging or electrochemical degradation.

Ageing and Resistance

Elastomers react particularly strongly to physical and chemical influences. Heat, radiation, liquid or gaseous media and biological processes change the properties of rubber materials. They cause a variety of processes that can lead to a physical or chemical modification and degradation of the material structures.

Ageing tests and resistance tests help to evaluate the suitability of elastomers for specific applications and conditions of use and to estimate their service life in use. They serve to define time and temperature limits and form the basis for the design of components.

Aging and durability

Heat Ageing

Heat ageing tests are used to simulate the ageing processes in a kind of time lapse in the laboratory. Based on the results of heat ageing tests, statements can be made about the temperature resistance of a material without the influence of contact media.

Aging and durability

Ozone Resistance

Ozone, a highly reactive gas, is formed near the ground by complex photochemical processes. In sufficient concentrations, it particularly damages highly unsaturated polymers, especially NBR, NR and SBR. In practice, this occurs mainly on pre-assembled, i.e. stretched, components.

Aging and durability

Media Resistance

To ensure the functional behaviour of elastomers, e.g. for seals, hoses or dampers, in relation to media, operating supplies, immersion tests are done. These provide information on the compatibility of the elastomers against the tested media and their chemical resistance.

Analytical Test Methods for the Determination of Formulations and Substances

One rubber is not like another. Elastomers, also thermoplastic elastomers, consist of a mixture of different components. In addition to the rubber, the other ingredients of an elastomer’s formulation also have an important influence on the properties and behaviour of technical rubber products in use.

The suitability and consistent quality of a product depend on its composition. Changes in ingredients often have a critical effect.

For this reason, it is often desirable and useful for users to characterise elastomers using analytical methods, identify ingredients and examine formulations.

Analytics, Formulations and substances

Thermogravimetric Analysis (TGA)

The evaluation of a formulation by means of TGA allows the quantitative determination of the compound ingredients. TGA is a helpful method to verify the formulation of a rubber material during initial sampling and, in case of doubt, to refer to it during series monitoring.

Analytics, Formulations and substances

Infrared Spectroscopy (IR Analysis)

Infrared spectroscopy, or IR spectroscopy for short, is a simple and fast method of determining the polymer and ingredients of an elastomer compound. It is used, among other things, to prove the sampling status of a formulation with regard to the substances it contains.

Analytics, Formulations and substances

Gas Chromatography with Mass Spectrometry (GC/MS)

Gas chromatography with coupled mass spectrometry (GC/MS) allows a deeper insight into the composition of elastomers. It provides information about the type of plastics, the composition of materials, the additives added or other substances contained.

Analytics, Formulations and substances

Scanning Electron Microscopy and Energy Dispersive X-Ray Spectroscopy (SEM-EDX)

In our Elastomer Institute, SEM-EDX analysis is mainly used for failure analysis and thorough material analysis. Wherever the digital microscope is at its limits, the SEM makes inhomogeneity, cracks and damages visible.

Special Functional Tests, Resistance Tests, Special Property Tests

In addition to individual and standard tests, we offer special functional, compatibility and property tests. These are designed for the use of rubber parts in typical media or under characteristic application conditions.

Many of the requirements and specifications come from the automotive industry and its suppliers, from fluid technology and from oil or additive manufacturers. However, other industries also have special requirements for rubber materials, which we are pleased to verify for you.

For example, we carry out compatibility tests for hydraulic or automotive oils and refrigerants, determine the resistance of materials to blow-by gases that occur in combustion engines. Alternatively, we analyse the reactions of materials to aqueous media and at low temperatures.

We work closely with well-known manufacturers from various industries.

Function and Compatibility

Oil Compatibility Test

We regularly test the resistance of elastomers to different oils. This includes the Bosch-Rexroth fluid rating and tests in hydraulic fluids in accordance with ISO 6072.

Function and Compatibility

Refrigerant Compatibility Test

We test the compatibility of elastomers in common FC refrigerants as well as in CO2 refrigerants. Among others, HFO-1234yf or R1234yf or R134a are part of our test range.

Function and Compatibility

Resistance to Coolants, Water and Steam

We carry out tests in water, steam, in cooling water and other aqueous mixtures up to over 200°C. We have approximately 70 autoclaves available for this purpose.

Function and Compatibility

Blow-by-Gas Resistance Test

Blow-by gas is generally understood to be gases that enter the crankcase in the combustion engine due to the overflow of the piston. We test materials for their resistance to blow-by gases in accordance with OEM requirements.

Function and Compatibility

Life Test based on Arrhenius

The influence of temperature on the service life of rubber products can be described very well using the so-called Arrhenius equation and expressed in the form of an (Arrhenius) straight line. We regularly carry out appropriate tests.

Function and Compatibility

Low Temperature Behaviour and Cold Flexibility

At low temperatures, elastomers gradually lose their outstanding property, the elasticity. When it comes to assessing the low-temperature limits of elastomers realistically and, above all, comparably, it is necessary to also evaluate the materials with meaningful test methods.

Function and Compatibility

Special Properties of Elastomer Materials and TPU

Some elastomers and thermoplastic elastomers have special features, certain parameters in the polymer or in the compound that are characteristic only for them. We use our test methods to reveal these special features.

Conformity test as per institute specifications, technical and factory standards

Usually, several material tests are combined in order to test and evaluate material conformity in accordance with certain institute specifications, technical standards or factory standards. In addition to specific limit values for basic properties, often the determination of the material resistance to defined media has priority.

As an accredited laboratory and approved DVGW testing laboratory, we evaluate and test your materials in accordance with industry and application-specific specifications. Our tests and test results are recognised as independent and reliable.

Please feel free to contact our laboratory for the following conformity tests:

Conformity testing in accordance with DVGW: for gas supply and consumption equipment, gas appliances and systems, applications in water supply and drainage or supply lines liquid hydrocarbons
Conformity testing in accordance with DIN EN ISO 9539: for materials in gas welding equipment or related processes
Conformity testing in accordance with 3A Sanitary Standards: for materials in the dairy and other food industries
Conformity testing in accordance withautomotive specifications: for materials in the automotive sector
Conformity testing in accordance with ISO 3601-5: for O-rings and O-ring material formulations

Conformance to specification

Conformity Test in accordance with DVGW

Since 2009, we have been a DVGW-approved testing laboratory for conformity tests in accordance with the standards DIN EN 549, DIN EN 681-1 and DIN EN 682.

Conformance to specification

Conformity Test in accordance with DIN EN ISO 9539

The requirements for materials in gas welding equipment, flame cutters or in allied processes are very high. DIN EN ISO 9539 defines criteria for the evaluation of materials. We check the conformity of your materials in accordance with DIN EN ISO 9539.

Conformance to specification

Conformity Tests in accordance with 3A Sanitary Standards

Special requirements are placed on moulded rubber parts and materials used in the food industry. Among other things, FDA 21 CFR 177.2600 (White List) and the regulations in accordance with 3-A Sanitary Standards are of particular importance here.

Conformance to specification

Conformity Tests in accordance with Automotive Specifications

Materials and components for the automotive industry undergo numerous tests and release procedures before they actually are used in an automotive application. We carry out tests for you in accordance with various OEM specifications.

Conformance to specification

Conformity Test in accordance with ISO 3601-5

The conformity test of an elastomer according to ISO 3601-5 includes the determination of hardness, tensile strength, elongation at break and compression set. Heat ageing tests and various immersion tests in reference media are also part of the examinations.

Testing of Component Properties and Special Parts

In addition to the comprehensive material tests that we offer at the Elastomer Institut Richter, of course we also take care of the component itself. We focus not only on identity testing, but also on visual and dimensional inspections. In recent years, we have also specialised in the monitoring of material properties directly on hoses.

Dimensional inspection
Visual inspection (regarding manufacturing defects, form and surface imperfections)
Identity tests
Testing on hoses

Component Testing

Dimensional Inspection

As part of quality control, failure analysis or parts qualification, we carry out dimensional tests for a wide range of technical elastomer products.

Component Testing

Visual Inspection regarding Form and Surface Imperfections

Final inspection as an important part of elastomer production is conducted using different methods. Depending on the type of component and the desired quality level, either sampling or 100% inspections may be used.

Component Testing

Identity Tests

Does the delivered or used component match the sampled and since delivered products? It is not possible to identify the material types just from the visual appearance. In an identity check, simple test methods quickly provide information about the product in question.

Component Testing

Tests on Hoses

In order to qualify elastomer materials for hoses, users often require testing directly on the hose. Since the complete hose cannot be used for the individual material tests, it is necessary to produce suitable test specimens from the hoses. For this purpose, we are well equipped.