This document discusses machines used to test the flexibility and durability of shoe soles. The QINSUNSTM 465 Whole Sole Flex Testing machine subjects shoe samples to repeated flexing to determine how much a cut in the sole grows with flexing. It has three workstations that flex shoes at 140 cycles per minute. Low temperature versions like the QINSUNSTM 465F test flexibility down to -20°C. These machines provide consistent evaluation of sole resistance to flex cracking.

1. Poor design, the selection of inferior materials or inadequate methods of construction can result in soles
that are vulnerable to fatigue cracking due to the repeated flexing induced when walking.
The QINSUNSTM 465Whole Sole Flex Testing machine allows for the determination of a sole’s
resistance to the growth of a cut during repeated flexing. This machine, commonly referred to as a
‘Footwear Flections flexing machine’, is designed for the assessment of complete bottom constructions
(including midsoles and insoles), and is used to comply with testing requirements specified in EU safety
footwear legislation.
This machine comprises of three workstations, presented horizontally for ease of loading, inspection and
measuring during the test. The samples are clamped into position and, as the machine operates, they are
subjected to repeated flexing cycles at the rate of 140 flexes per minute. The number of cycles completed
is recorded on a counter, which also allows for a total number of flexes to be pre-set.
The machine can be used to conduct a number of tests, including QINSUNTM161:2004, EN ISO
20344:2004 8.4.2, DIN 53543 Section 6.3 1979, and BS EN ISO 17707:2005.
As specified in EN ISO 20344:2004 8.4.2 or QINSUNTM161:2004, a controlled cut is introduced into the
soling using a chisel (STD 465C) and an associated jig (STD 465J). On completion of a set number of
cycles, the growth of the cut is determined by inspection and measurement.
Low temperature testing is not specified as a requirement for EU safety footwear, although a wide variety
of materials become brittle at low temperatures. This is also often accompanied by an increased
vulnerability to crack growth under repeated flexing – an important consideration when footwear is used
in a cold natural or working environment. QINSUN produces a variant of the STM 465 Flex Testing
machine, the QINSUNSTM 465F, which allows the tests to be carried out at low temperatures (down to
-20°C). The flexing stations are contained in a temperature-controlled cabinet but, in other respects, the
STM 465F operates in the same manner as the standard QINSUNSTM 465 machine. Both machines are
protected with a fully interlocked guard system to protect the operator from injury while performing the
test.
Whether verifying a new soling design or batch auditing to confirm consistency of materials or
construction, the QINSUNSTM 465 and STM 465F machines offer a consistent assessment of sole
resistance to flex cracking.
Should testing be required for non-safety footwear, other sole flexing machines are available, notably the
Bata Belt flexing machines QINSUNSTM 612 and STM 612F for low temperature testing, and the Ross
flexing machine QINSUNSTM 141 and its equivalent low temperature test machine, STM 141F.
The Footwear Flections Tester is supplied in both single and twin station formats and the action
simulates the flexing of footwear during wear. The angle of flex is adjustable up to 50°. The machine may
be used to predict the failure of footwear in wear. It is particularly useful in assessing problems
associated with bottom construction.
Footwear is clamped to the machine at the toe end using the appropriate toe clamp from one of five pairs
supplied. The heel end is secured to the flexing bar. A predetermining counter is fitted and once the
appropriate number of flexes has been registered, it will stop the machine so that the shoe can be
inspected.
The moving parts of the machine are covered by a hinged guard which is fitted with the latest safety
device to prevent access while the machine is still in use. The machine is robust and non-corrosive
materials are used where applicable in its construction.
The machine is robust and non-corrosive materials are used where applicable in its construction.

2. A similar machine is available for testing high leg boots where water depth can be increased to cover the
whole forepart of the footwear up to eyelet level.
Read more: http://www.qinsun-lab.com/Products/whole-shoe-flexing-machine.html