10 Common Tests in UTM

A universal testing machine or UTM machine is a very versatile machine that has the ability to conduct multiple tests. We shortlisted the 10 tests that performed better in UTM.

The following are 10 tests and standards that are commonly used with universal testing machines:

tensile test

Compression testing (for thin plastic films) is done in a UTM machine or a dedicated Tensile Testing Machine by grabbing/clamping the test specimen at both ends and straightening it until it breaks. In tension mode, the UTM machine will move vertically upwards. Usually after the tensile test, some parameters are calculated, such as tensile strength, elongation percentage, maximum force, etc.

Standard Use: ASTM D 882 – Standard Test Method for Tensile Properties of Thin Plastic Sheeting.

compression test

Compression testing is performed in the opposite direction compared to tension mode (i.e. the machine will move vertically downward).

For compression testing, grips called compression plates (depending on the size of the test specimen) are used as the upper and lower grips: the test specimen is then placed between these grips and compressed to a certain load or expanded, or until the specimen breaks.

In general, the types of materials subjected to compression testing are:

• concrete

• hardware

• plastic

• ceramics

• composite material

• corrugated box

Use standard:

• ASTM D 642 – Determination of Compression Resistance of Containers, Assemblies, and Unit Loads

• ASTM D 695 – Standard Test Method for Compressive Properties of Rigid Plastics

Seal Strength Test

Seal strength testing or seal integrity testing is done by UTM machines to check the maximum force required to break the seal.

Performing this test seals the pack, usually done using a heat sealer at a specific temperature, pressure and dwell time. This test is performed in stretch mode. The final result of the seal strength test is "maximum force".

This test is performed to check the force required to open a specific package: the actual seal strength of the packaging line is optimized by controlling the sealing time, temperature, pressure, etc.

bond strength test

Bond strength testing is performed using a UTM machine to check the adhesion between two layers of any material.

The final result of the bond test is measured in the form of an "average force": here the pattern is checked at the end of the test, if the pattern emits a uniform force, it is concluded that the adhesive is correctly applied to the test material/structure, if at If any peaks/troughs are observed in the graph, it is concluded that the adhesive was not applied evenly to the test material.

Gliding test

Glide testing is done with UTM machines to check smoothness between any 2 surfaces.

This test can be performed in two modes, namely tension and compression, depending on the test to be performed and the sample to be tested.

A suitable example of a gliding force test is when performing this test on a syringe/syringe in the pharmaceutical industry. In this case, the test is performed in compression mode, where the plunger pushes the injection head to a certain limit.

The final result observation is the "average force" and graph, which is evaluated during the test to check for peaks/troughs.

Puncture test

The puncture test is carried out in the UTM machine, the sample is placed in the bottom fixture, in which a certain circular area is fixed at the periphery, and the central area remains hollow (this is done as per the standard).

Then, a "piercing probe" is used as the upper grip, which travels down until the test material is pierced. The result of the calculation is the maximum force required to pierce the material, this result is called "puncture resistance".

3-point bend test or elasticity test

The 3-point bend or bend test is done in the compression mode of the universal testing machine, where the material length is held on 2-end supports (unsupported lengths are defined by the standard), and the plunger will exert pressure on the center of the material until a certain Extend or until it breaks. The final result of the calculation is "elastic mode".

Synergy of friction tests

The degree of smoothness between two materials is determined by sliding one material over the other under specified test conditions. The results observed after testing were the static co-effect of friction (actuation force) and the kinetic co-effect of friction (average force while sliding). These results relate to the sliding properties of plastic films of wide concern in packaging applications.

A dedicated coefficient for the friction Tester is also available, which provides some additional functionality: but it is possible to successfully perform this test with a universal testing machine, since in both cases the sensing device is the load cell, this should be very high accuracy and repeatability.

Standard Use: ASTM D 1894 – Standard Test Method for Static and Kinetic Coefficients of Friction of Plastic Film and Sheeting.

spring test

UTM's     Spring Test is a very specialized application. Springs can be tested in both tension and compression modes, depending on the end application for the particular spring.

In compression mode, the spring is placed between 2 compression plates and compressed to a predefined compression point (expansion). The measured result is 1. Load/Force 2 at a predefined compression point. Spring rate (load per mm).

In tension mode, the spring is placed in the tension hook and pulled to a given tension limit. In this case, the generally observed end result is the load at a given tension limit.

Springs can also be tested using a universal testing machine in cycle mode, which will use both tension and compression modes for testing. Here a spring will be placed between compression plates or tension hooks and the spring will rise and fall depending on the number of cycles given. The observed results in this case are the peak load at 1 cycle and the peak load at 1 cycle; the rate of decay of these two cycles tells us how the shape of the spring changes. Also, measure the full length of the spring (total spring height) before and after the cycle test.

Food Texture Analysis

In the food industry, UTM machines are often marketed as "texture analyzers" with some adjustments made especially for the food industry.

When it comes to food testing, no standards are given as each product has a different taste, texture or formula, even though the final product may look similar. So each company makes its own standard which is followed only in its organization (locally or globally) and this standard is not shared with others to maintain confidentiality.

Food texture analysis can be performed with a universal testing machine using various fixtures such as different kinds of blades, different types of probes (such as ball probes, cylindrical probes and conical probes of different diameters). The end results that can be derived after performing this test are firmness, brittleness, hardness, extensibility, brittleness, stickiness, cohesion, stickiness, etc.

As mentioned earlier, organizations should develop standards for which fixtures should be used when testing with a universal testing machine (because there are a wide variety of fixtures), and what results should be obtained after the test is completed.