Specifications Of A Universal Testing Machine

In some industries, it becomes essential to test the tensile and compressive strengths of a material. Some universal testing machines are also equipped to determine the material hardness and also to conduct a torsion test of any given material. A universal testing machine comes to the rescue in all these situations. It consists of three main units - a loading frame, a hydraulic pump and an electronic control panel.

The loading frame of a universal testing machine is made up of a table and a central cross head. The area between the central cross head and the table is used to carry out a compression test. The tensile test on the other hand is conducted between the centre crosshead and the upper cross head. The whole unit is generally made up of 6 pillars, which give the machine enhanced stability. Load sensing is achieved using a transducer based on strain gauge and the elongation/compression is calculated by means of a rotary encoder.

The hydraulic pumping system is comprised of a motor driven multi plunger type pump. The hydraulic circuit has a maximum pressure of around 200 bars. The hydraulic pump provides the loading frame ram with a continuous oil flow, which enables the movement of the ram. The direction of oil flow determines the direction of the ram movement. Some UTMs are also provided with a pressure switch that is used for core cutting purposes. Other than these the hydraulic circuit also contains a release valve to relieve the system from hydraulic load and a load control valve, which is used to regulate the load on the test specimen.

The third component of a UTM is an electronic control panel. This panel is used to control the main pump and also the cross-head movement. There is an additional switch which enables the fast movement of the ram for saving time during specimen set up. The electronic control panel may sometimes contain a digital microprocessor based display system. Some machines also have ports to be connected to the computer for easily retrieving the data collected during the test. Some advanced UTMs also provide real time load versus displacement graphs.

A universal testing machine is an integral component of any material testing laboratory. The UTM offers a wide range of flexibility to test a given material specimen for its various load bearing capacities. Some of the advanced UTMs can also test a specimen for bending stresses and moments, which are crucial design aspects.