Force testing determines how a material would react when it is subjected to compression and tensile load. The force tester helps move the mounted force gauge up and down during product testing. They are widely used across industries for testing food, pharmaceutical products, plastics, paper, medical devices, textiles etc.
They are available in mechanical, motorised, digital and pneumatic versions as per the demand of industrial applications. During R&D, force testing is generally used to compare materials, determine their strength or design new products that meet the desired requirements. Moreover, it is also used to check if the given product batch meets standard specifications.
However, choosing a suitable system for force testing depends on the required force range and testing applications. For example, applications that require testing of compressive, tensile, flexural, fracture and shear may need different systems, grips & fixtures to perform each of these tests. In addition, these tests may also require the users to vary the amount of load applied to measure the material response, such as in static and dynamic testing
Therefore, it is extremely crucial to choose a suitable force tester for your intended testing applications to ensure accurate measurement. Other than the system itself, it is also equally important to select the right fixtures and grips. This may vary depending on the objects to be tested. The grips should be chosen to firm hold on the sample or object under measurement to avoid slippage or any other changes that might affect the performance of the sample under load.
Choosing the Correct Grips and Fixtures for a force tester
Grips and fixtures are primarily chosen based on two reasons: the testing applications and their testing capacity. High-quality grips and fixtures minimize the slippage and bending strains that invalidate the results. While correct grip ensures material is firmly held in its place, fixtures are used for proper alignment. When both elements are properly maintained, the test results would ascertain accuracy and reliability.
- Choosing grip types for force testing
A material under force measurement might slip from the grip if the following applies; the clamping force is not sufficient, the surface area of the grip jaw faces is not securing enough surface area of the material or the jaw surface is not suitable for the material. Moreover, you also risk breaking the material if the chosen grip is not suitable for the tested material.
Therefore, before choosing the grips, you must consider the key factors such as grip design, grip faces, grip capacity, specimen material, geometry and its impact.
Here are some of the most common grips you can consider based on the popular application.
1. Wedge Action Grips
They are the most commonly used self-tightening grips that offer the advantage of continuously holding the material tighter as force increases. Wedge action grips work on the principle that two wedges are pulled together as force (tensile force) is applied to the material under measurement. The wedges allow the material to be gripped without altering the vertical position of the grip faces.
2. Vice Grips
They are the manually-tightened grip types suitable for flat objects such as sheet metal, plastic, paper, composites sheet, etc. Vice grips offer the advantage of quick set-up and easy loading of samples.
3. Eccentric/ Self-tightening Roller grips
They are the self-tightening grip type used for force testing of flat samples. Eccentric grip function by first tightening the sample by a lever and then using the serrated rollers to prevent sample slippage.
- Choosing the correct fixtures for force testing
In compression force testing, a fixture holds and supports a material under measurement. Based on the applications, T-slot tables or multithreaded bases can be incorporated into the force tester to assist inaccurate measurement.
1. Bend and Flexing fixtures
These fixtures are used for testing bending materials such as fibre, plastic, metals etc. These fixtures use adjustable rollers with linear scaling to apply force to the sample in the desired/specific areas.
2. T-Slot and Multithreaded fixtures
These fixtures provide additional fixing to the samples when they need to be tested as a group. When T-slot is combined with a multi-threaded base plate, the material gains mounting flexibility during force testing.
If you face difficulties in force testing applications, contact our engineers at Bestech Australia. We possess considerable expertise in industrial testing and measurement of physical parameters and we offer high-quality force testers from Ametek. We would assess your requirement and assist you in designing and offering efficient, cutting-edge sensor solutions, well-suited to your force testing needs.
