Many plastic materials do not have certain melting points. Therefore, a specific criterion must be defined as the softening point which is obtained by SHV-303. In SANTAM machines, the capability of VICAT and HDT testing is included for each cell individually. For this purpose, two types of needle and round shape probes (which are replaceable) are used for VICAT and HDT tests to apply the load. In HDT tests, three support lengths can be selected accurately as per the standard because the specimen should pass 3-point flexure test. In this test, the load is applied by standard weights in binary form by means of the plunger to the center of the test piece then the sample is plunged into oil and heated with a specific rate leading to deformation and is measured by a dial gauge with accuracy of 0.01mm. In VICAT test, the standard load is 5N and 10N that is applied by a needle-shaped indenter on the circular or square discs. The rest of the test is the same as HDT test. Each test cell has a special design to take the test sample out of the oil or get it into the oil by means of a locking mechanism. Weights loading and unloading, accurate height adjustment of the dial gauge and keeping the spring force on the specimen constant, is performed by other mechanisms. Silicone oil is used to transfer heat to plastic samples. The oil is heat resistant up to 250\u02daC. There is an alarm for controller oil overheat that stops the increase in heat. Thermostat overheat protection system is used for more safety. An accurate sensor and PID controller (0.1\u02daC resolution) control the oil temperature that can increase the heating rates to 50\u02daC\/hr and 120\u02daC\/hr (other rates can be applied). Moreover, a sensor is located beside each cell to report the samples temperature. A special stirring system is used to keep oil temperature constant in each test procedure in all cells. After finishing the test, the result of each cell is recorded, and the average is reported. By pushing a button, the cooling system is activated to cool the oil temperature down to the ambient pressure. Direct calibration of weights in each cell (taking into account the oil buoyancy force and the applied load of dial gauge spring) is another capability of the machine, which verifies the accuracy of values and loads in each step of the test. For calibration of the temperature sensors, a special place next to each sample is foreseen. It has a touch screen HMI display (LCD) using PLC system that indicates all measuring tools, implements all commands, and draws the specimen deflection or deformation graphs when temperature increases in each cell.<\/p>\n
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