UTM is a very versatile machine and many tests can be performed with single UTM. We have shortlisted 10 of the most performed tests in UTM.
10 commonly performed Tests and standards used are mentioned below:
Tensile test (for thin plastic films) is done by gripping / clamping the test sample at each ends and is pulled until it breaks. In Tension mode, machine will move in upwards direction vertically. Typically after tensile test, some parameters like Tensile strength, % Elongation, Maximum force, etc. are calculated.
Standard Used: ASTM D 882 – Standard test method for tensile properties of thin plastic Sheeting.
Compression test is performed in opposite direction as compared to Tension mode (i.e. the machine will move downward direction vertically). For compression test, fixtures called compression platens (of different sizes depending on test specimen) are used as upper and lower fixtures; then test specimen is placed between these fixtures and compressed up to certain load or extension or till the sample breaks.
Generally types of materials subjected to compression test are:
- Corrugated Boxes
- ASTM D 642 – Determining Compressive resistance of Shipping containers, components and unit loads
- ASTM D 695 – Standard test method for compressive properties of Rigid Plastics
Seal Strength Test
Seal strength test or Seal Integrity test is done to check maximum force required to break a seal of a package. To perform this test sealing of a package is done by using a heat-sealer at generally at specific temperature, pressure and dwell time. This test is performed in tension mode. Final results checked for seal strength test is ‘Maximum Force’. This test is performed to check the how much force will be required to open a particular package; with help of this result, the actual seal strength is optimized at the packaging line by controlling seal time, temperature, pressure, etc.
Bond Strength Test
Bond strength test is performed to check the adhesive force between the two layers of any material. Final result for the Bond test is ‘average force’, also graph can be checked at the end of the test, if the graph is uniform then it can be said that adhesive is properly applied to the test material / structure and if any peaks / troughs are observed in graph then it can concluded that the adhesive has not been applied uniformly to the test material.
Gliding Force Test
Gliding force test is performed to check the smoothness between any 2 surfaces. This test can be performed in both modes tension as well as compression, depending on the test to be performed and the sample to be tested. Best example for gliding force test is when this test is performed on syringes / injections in Pharmaceutical sector. In this case, the test is performed in compression mode and plunger will push the head of the injection up to certain limit and final results are checked as ‘average force’ and also graph is evaluated to check and peaks / troughs during the test.
Puncture test is performed by placing the sample in the bottom fixture where a certain circular area is secured as secured at the perimeter and the centre area is kept hollow (this is done according to standards). Then a ‘puncture probe’ is used as upper fixture and this probe travels downwards until the test material is punctured. The result calculated is maximum force required to puncture a material, this result is called as ‘puncture resistance’.
3-point bend Test or Flexural test
3-Point bend or Bend test is done in compression mode where a length of material is kept on support at 2 ends (the unsupported length is defined as per standard) and a plunger will apply the pressure at the centre of the material till the certain extension or till it breaks. Final results calculated are ‘Flexural Modulus’.
Co-efficient of Friction Test
Friction test is performed to determine the smoothness between two materials by sliding one material over another at specified test conditions. Results observed after the test is performed are Static Co-efficient of Friction (starting force) and Kinetic Co-efficient of Friction (average force while sliding). These results are then related to slip properties of plastic films that are of wide interest in packaging applications.
Dedicated machines to measure Co-efficient of Friction are also available which gives some additional feature; but it is possible to successfully perform this test with Universal Testing Machine as in both cases, sensing device is load cell, which should be of very high accuracy and repeatability.
Standard used: ASTM D 1894 – Standard test method for Static and Kinetic Coefficients of Friction of plastic films and sheeting.
Spring testing in UTM is very specialized application. Springs can be tested in Tension as well as Compression mode, depending on final application of the particular spring.
In Compression mode, a spring is placed between 2 compression platens and is compressed till the pre-defined compression points (extension). Results measured are 1. The load / force at pre-defined compression points 2. Spring rate (load per mm).
In Tension mode, springs are placed in tension hooks and are pulled till the given tension limit. Final result generally observed in this case is the load at the given tension limit.
Springs are also tested in cyclic mode, this mode will use both tension and compression modes for testing. Here a spring will be placed between a compression platen or tension hooks and spring will go up and down, depending on given number of cycles. Results observed in this case are peak load at 1st cycle and peak load at last cycle; the decay rate at both these cycles tells us how shape of the spring is changed. Also, full length (total height of the spring) of the spring is measured before and after the cycle test.
Food texture analysis
In Food industry, UTM is generally marketed as ‘Texture analyser’ with some tweaks given specially for food industry. In case of food testing, there are no standards given because each product made has different taste, texture or formula even though the end product might look similar. So every company comes up with their own standard which is followed only in their organisation (either local or global) and this standard is not shared with anyone else to maintain secrecy.
Food Texture Analysis can be performed using various fixtures available like different variety of blades, different types of probes like ball probe, cylindrical probe and conical probe which are available in different diameters. Final results which can be obtained after performing this test are Firmness, Crunchiness, Hardness, Extendibility, Brittleness, Gumminess, Cohesiveness, Stickiness and more…
As said earlier, a standard should be made by the organisation which should give proper directions as to which fixtures should be used while testing (as wide variety of fixtures are available) and which results should be obtained after completing the test.
Disclosure: The test methods and standards given above are the general purpose tests for explanation. There are other than the mentioned standards available too. To serve your purpose it is recommended to consult an expert for appropriate advice.
Apart from above mentioned tests there are lot other tests also which can be performed successfully using UTM. It is just the matter of knowing which tests are exactly need to be performed for your material and why? UTM is the all-in-one machine which most used in many of the QC departments and R&D laboratories.
Leading UTM Suppliers in India are:
- LLOYD Instruments