SATRA STM 612 SATRA/Bata belt flexing machine
The SATRA/Bata belt flexing machine provides one of the best indications of the risk of cracking of shoe soles due to flexing in wear.
The test is conducted by fixing the sole unit to an endless belt which passes around two pulleys of differing diameters. The larger main drive pulley provides the rotation while the smaller of the two pulleys determines the severity of the flexing action. The equipment is supplied complete with three small pulleys of varying diameters to increase or decrease the amount of flexing.
The endless belt can usually accommodate six sole units, subject to the style and size. Sole units are bonded to the belt using a strong adhesive. When very stiff sole units are tested it may be necessary to stitch the toe of the sole unit to the belt.
The belt is made of canvas and its construction allows the number of complete cycles to be counted which is equal to the number of flexes of the test sample.
The flexing area is provided with a full guard interlocked with the machine controls to ensure the guard cannot be opened until the belt has stopped.
The control cabinet located at the side of the machine houses the motor drive controls as well as a counter which can be pre-set to stop the machine when a predetermined number of flexes has been reached. This allows the examination of the sole units at intervals throughout the test duration. The standard machine is supplied as a bench top machine, although a separate stand can be supplied at additional cost.
A low temperature variant allows the flexing to be carried out at sub-zero temperatures, enabling the increased risk of cracking due to cold weather. The complete flexing mechanism is built into an insulated chamber where the temperature can be reduced to a pre-set level. The lowest temperature achievable on this model (STM 612F) is -20°C subject to ambient temperature. STM 612F is supplied complete with a stand that houses the refrigeration unit.
The machine is suitable for the testing of all shoe sole units and can also be used with other flexible materials.