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New standard for sole testing of safety shoes
- Oct 30, 2018 -

       Safety shoes are a general term for safety shoes and protective footwear. They are generally used to protect the feet and legs from foreseeable injuries in different workplaces.

       Safety shoes SATRA Ross flexure tester (STM 141) Bata belt test If the sole contains large splints or a complex design with different materials, the best way to measure the resistance of SATRA is the Bata belt tester. This is a generally accepted test that reproduces the results associated with actual wear. Bond the front of the complete sole (minus the heel but still contain any cavities or midsole material) to the canvas belt. This portion is driven by driven mandrels of different diameters so that when the belt is driven onto the mandrel, the sole is repeatedly flexed and circulated. The driven mandrel is typically 90 mm in diameter but can be changed to 60 mm or 120 mm to increase or decrease the degree of flexing. Unlike the Ross Flex test, it is not necessary to cut the sole. The test runs for 50,000 cycles and is continuously visually evaluated during the run. Record the length and depth of any crack. This test is generally carried out at room temperature, but in SATRA, the sole can be tested at temperatures as low as -15 °C. The Bata Belt Flexometer (STM 459) is equipped with three interchangeable driven mandrels of 60 mm, 90 mm and 120 mm as standard, with a rotational speed of 90 deflections per minute on a smaller mandrel. Lower temperature versions of the machine are also available to perform tests at temperatures as low as -20 °C.

Bennewart Testing As with the old standard, the new standard for safety footwear (EN ISO 20344:2004) requires the Bennewart machine to be used to test the sole. More testers prefer to use the Bata tape test method to test the entire front of the sole. The insole is an important part of the sample, and an open cut is cut on the nominal deflection curve using a chisel similar to Ross. The sole grips the ends and the roller pushes the insole to flex the sole 90 degrees. The degree of increase in the incision was measured after 30,000 cycles of operation at room temperature. This test can be performed below zero in SATRA if required. This is a demanding test and is best suited for durable footwear with a sturdy sole. For casual, stylish and everyday wear, this test is considered too strict, especially when the sole is thick. SATRA's Rennewart Full Sole Flex Tester (STM 465) is designed to ensure a balanced force, requiring less force to perform tests and smoother results. The instrument clamp is rigid and operates strictly according to standards. A modified version of the Bennewart tester, which uses a spring-acting clip, does not perform this test as standard. However, a low temperature version of this instrument can be provided to perform the test at temperatures as low as -20 °C. A chisel-mounted cutting jig (STM 465) is available to help accurately cut the sole.

       During the entire life of the footwear, strain is generated due to the flexing of the foot, or the sharp edges cut the indentation and pierce the sole may wear cracks or breaks. Extreme temperatures (especially below zero) and contamination (such as oil) may also accelerate the cracking of the sole. From this point of view, it is very important to test the scratch resistance of the sole. There are many test methods to choose from, so it may be difficult to choose the correct method. Here are three main methods of flexural testing, applications for rubber and plastic soles, and SATRA's equipment for performing these tests.

       Using the Bennewart method

       Test Safety Shoes Ross Flex Test For a smooth design with a small or no sole pattern, a Ross Flex Test Machine (SATRA TM60) can be used. Three test pieces of 150 mm x 25 mm are typically removed from the shoe with the longer edge parallel to the heel seat. A 2 mm chisel was used to cut a slit in the sample and the sample was placed in a flexing machine so that the slit was directly above the flexing mandrel. The incision can be measured before and after the test to calculate the extent of the incision. This test typically runs 150,000 cycles at a temperature of -5 °C. This can help to form a measurable increase in the incision over a reasonable time frame. The only exception is to test thermoplastic rubber at +20 ° C because this material performs better at lower temperatures. The SATRA Ross Flex Tester (STM 141) can accommodate up to 12 specimens simultaneously. The machine deflected the sample at a standard speed of 60 deflections per minute. However, machines that can provide 100 deflections per minute are used for this type of testing in the ASTM version. In addition to standard machines, lower and higher temperature devices are available. This temperature range is from ambient temperature to -20 ° C and from ambient temperature to +40 ° C.

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