Specialist Testing in Detail
ARTIS has a range of more specialist test equipment for performing some functions specific to an end user or more fundamental measurements.
- Rubber compound processing
- Cured rubber and other materials
- Bespoke product based equipment
Rubber Compound Processing
The TMS Rheometer is a bi-conical rotor device designed to look at the shearflow properties of rubber compounds. The test chamber is filled through an injection transfer process and the rotor can be programmed to generate shear rates of up to 100 S-1 . This means the TMS is far more useful as a predictor of compound performance during processing. We have developed techniques to estimate the degree of lubricated ‘wallslip’ a compound can produce during flow. This phenomenon will have a large influence on the ‘extrudability’ of a compound.
By curing rubber around a smooth rotor and then measuring the forces necessary to break adhesion between the rubber and the rotor it is also possible to quantify the degree of interaction between compounds and mould surfaces. It is also possible to use this type of test to assess the efficacy of mould release agents or the propensity of a compound to exhibit mould fouling.
ARTIS also has a capillary Rheometer capable of generating shear rates of up to 5000S-1 – comparable to those seen in injection moulding operations and can be used to help generate data for injection moulding simulation packages such as “Moldflow” alongside cure and thermal property data also generated in house.
Cured rubber and other materials
Dynamic Mechanical Analysis (DMA) enables evaluation of the effects of temperature, strain, frequency and exposure to liquids or gases on the dynamic properties of your material. Data collected from tests such as this can be used to generate high frequency dynamic property information, which is appropriate for acoustic applications. We also have experience in the use of DMA as a predictor of key tyre compound properties such as wet grip and rolling resistance. Use in this way can have a significant effect on the tyre tread compound development cycle, limiting development costs and maximising results.
Follow the case study link for case study on the application of DMA to product design.
Electrochemical measurements can be used to generate information concerning the potential for galvanic corrosion where rubber is in direct contact with metal. This has been particularly useful for coolant hose and aerosol seal applications. ARTIS has the capability of using both automotive specified tests for ECD of coolant hose, as well as in house techniques which are considered to be more rapid and realistic.
ARTIS has a second tensometer capable of performing specific tests at temperature (-80°C to 200°C) or on unusual samples / test regimes.
For example hot tear testing at 180°C has been carried out on this machine to reflect the demoulding behaviour. Stress relaxation and creep testing can also be performed. Functionality testing of aerosol cans, dairy liners and respirator valves has also been performed using this equipment in a unique configuration.
Bespoke product based equipment
ARTIS has in the past created specific pieces of equipment to evaluate products because there was nothing in the market that would do the job required. Examples of this are:
The chipping and chunking rig was developed to evaluate tracked vehicle pad wear patterns and rates. It was developed in conjunction with the UK MOD and gave 95% correlation to service wear rates and patterns. Since then it has been used for rubber crawler track wear evaluation as the mechanisms are the same, and is currently being converted to be a constant load fatigue facility.
The milkstone rig was developed to simulate the service conditions seen by a milk liner without the need for farm trials. Rubber can be tested for interactions with milk and cleaning chemicals on the basis of physical and chemical changes that take place within the rubber.
This work has led to a drive for new liner materials and a greater understanding of how the liner interacts with its environment.
