【Integrated】Shoes sole testing method

During the entire service life of the footwear, the safety footwear is strained due to foot flexing, or the sharp edges cut open the nicks and pierce the soles of the shoes and may wear or crack or break. Extreme temperatures (especially sub-zero) and pollution (such as motor oil) may also accelerate the cracking of the sole. From this point of view, it is very important to test the flex resistance of shoe soles. There are many test methods that can be selected, so it may be difficult to choose the correct method. The three main flexural test methods and applications for rubber and plastic soles, as well as the equipment SATRA provides for these tests, are presented below.

Using the Bennewart method

Testing Safety Shoes Ross Flex Test For smooth and shoe sole designs with little or no tread pattern, the Ross Flex Test Machine (SATRA TM60) can be used. Three pieces of 150 mm x 25 mm test pieces are generally removed from the shoe, with the longer edges parallel to the heel seats. An incision was made in the sample using a chisel with a 2 mm blade, and the sample was placed in a flexing machine so that the incision was located directly above the flexing mandrel. The incision was measured before and after the test, and the degree of enlargement of the incision can be calculated. This test typically runs for 150,000 cycles at a temperature of -5°C. This can help create measurable incision increases over a reasonable time frame. The only exception is testing the 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 at the same time. The machine flexes the sample at a standard speed of 60 deflections per minute. However, a machine capable of flexing 100 times per minute can be provided for performing this test of the ASTM version. In addition to standard machines, lower and higher temperature equipment can also be provided. This temperature ranges from ambient temperature to -20°C and from ambient temperature to +40°C.

SATRA Ross Flex Tester (STM 141) Bata Band Test

If the sole contains a large splint or a complex design that integrates different materials, the best way SATRA tests flex resistance is the Bata band tester. This is a generally accepted test that repeatedly produces results that are related to actual wear. The front of the complete sole (minus the heel but still containing any cavity filler or midsole material) is bonded to the canvas belt. This section is driven by the driven mandrels of different diameters, so that when the belt is driven onto the mandrel, the sole is cyclically flexed repeatedly. The driven spindle is generally 90 mm in diameter but can be changed to 60 mm or 120 mm to increase or decrease the degree of deflection. Unlike the Ross flex test, it is not necessary to cut the sole. The test runs for 50,000 cycles and a continuous visual assessment is performed during the run. Record the length and depth of any cracks. This test is generally performed at room temperature, but in SATRA, soles can be tested at temperatures as low as -15°C. The Bata Band Flexometer (STM 459) is equipped with three interchangeable driven spindles with dimensions of 60 mm, 90 mm and 120 mm as a standard configuration. The speed of rotation is 90 flexes per minute on a smaller mandrel. A lower temperature version of the machine can also be provided to perform tests at temperatures as low as -20°C.

Bennewart test

As with the old standard, the new standard for safety shoes (EN ISO 20344:2004) requires the use of a Bennewart machine to test the sole. More testers prefer to use the Bata band test method so that the entire front of the shoe can be tested. The insole is an important part of the sample. Using a chisel similar to Ross, an incision is made in the nominal flexion curve. The two ends of the shoe are clamped, and the roller pushes the inner bottom to flex the sole 90 degrees. The incision increase was measured after 30,000 cycles at room temperature. If necessary, this test can be performed at sub-zero SATRA. This is a demanding test and is best suited for durable footwear with a strong sole. For casual, fashionable and everyday footwear, this test is considered too strict, especially when the sole is thick. SATRA's Rennewart Total Sole Deflection Tester (STM 465) is designed to ensure balanced forces and therefore requires less force to perform tests, resulting in smoother operating results. The instrument clips are rigid and operate in strict accordance with the standard. A modified Bennewart tester adapted to use a spring-action clip does not perform this test in accordance with the standard. However, a low-temperature version of this instrument can be provided to perform tests at temperatures as low as -20°C. A cutting jig (STM 465) with a chisel can be provided to help accurately cut the sole.