sole test method of safety shoes

During the whole service life of footwear, the safety shoes may be worn, cracked or broken due to the strain caused by foot flexion, or the sharp edge cutting notch and piercing the sole. Extreme temperatures (especially below zero) and contamination (such as oil) can also accelerate sole cracking. From this point of view, it is very important to test the anti crack property of sole. There are many test methods to choose, so it may be difficult to choose the right method. Here are three main flexure test methods and applications for rubber and plastic soles, as well as the equipment provided by SATRA for these tests

the benneart method

is used to test the Ross flexure test of safety shoes. For smooth sole designs with little or no sole pattern, the Ross flexure test machine (SATRA tm60) can be used. Generally, take 3 pieces off the shoes, and the size is 150 mm × The longer edge is parallel to the heel base. Use a 2 mm chisel to make a cut in the sample, and then place the sample into the flexure machine so that the cut is directly above the flexure mandrel. The increase of incision can be calculated by measuring the incision before and after the test. The test is generally operated at – 5 ℃ for 150000 cycles. This can help to form a measurable increase in incision within a reasonable time frame. The only exception is the testing of thermoplastic rubber at + 20 ℃ because the material performs better at lower temperatures. SATRA Ross flexometer (STM 141) can hold up to 12 specimens at the same time. The machine flexes the sample at a standard speed of 60 deflections per minute. However, a machine with 100 deflections per minute can be provided for this ASTM version of the test. 1n addition to standard machines, lower and higher temperature devices are available. Thus, the temperature range is from peripheral temperature to – 20 ℃ and from peripheral temperature to + 40 ℃

SATRA Ross flexometer (STM 141) Bata band test

if the sole contains a large splint or a complex design integrating different materials, then the best way for SATRA to test the crack resistance is the Bata band tester. This is a generally accepted test that can reproduce results related to actual wear. Bond the full front of the sole (minus the heel but still contains any cavity filler or insole material) to the canvas strap. This part is driven by driven spindles of different diameters, so when the belt is driven to the spindle, the sole is repeatedly flexed. The diameter of the driven shaft is generally 90 mm, but it can be changed to 60 mm or 120 mm to increase or decrease the degree of deflection. Unlike the Ross flex test, there is no need to cut the sole. The test runs for 50000 cycles, and continuous visual evaluation is conducted during the operation. Record the length and depth of any cracks. The test is usually carried out at room temperature, but at SATRA, the sole can be tested at temperatures as low as – 15 ℃. Bata belt flexometer (STM 459) is equipped with three replaceable driven spindles of 60mm, 90mm and 120mm as standard. The rotation speed is 90 deflections per minute on smaller spindles. A lower temperature version of the machine is also available to perform tests as low as – 20 ℃< Like the old standard, the new standard for safety shoes (EN 1SO 20344:2004) requires the use of benneart machine to test soles. More testers prefer to use the Bata band test method, which can test the entire front of the sole. The insole is an important part of the sample, and a chisel similar to Ross is used to cut on the nominal deflection curve. The two ends of the sole are clamped, and the roller pushes the inner sole to flex the sole by 90 degrees. The increase of incision was measured after 30000 cycles of operation at room temperature. 1f necessary, this test can be performed below zero at SATRA. This is a demanding test and is best used for durable footwear with strong soles. For casual, fashionable and everyday shoes, the test is considered too strict, especially when the soles are very thick. SATRA's rennewart full sole flexometer (STM 465) is designed to ensure force balance, so it requires less force to perform the test, so that the running results are more stable. The clamp of the instrument has large rigidity and is operated strictly according to the standard. A modified bennewart tester is adapted, which uses spring action clamp and does not carry out the test according to the standard. However, a low-temperature version of this instrument is available to perform tests at temperatures as low as - 20 ℃. A cutting fixture with chisel (STM 465) can be provided to help cut the sole accurately

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