The SATRA STD 185 sole adhesion tester
An overview of this small but important piece of equipment.
The well-proven SATRA STD 185 sole adhesion tester is designed to measure the strength of the adhesion of stuck-on and moulded soles at both the toe and heel of finished footwear in the shoe factory. It is equally valuable for use in the testing laboratory.
Figure 1 shows an STD 185 instrument being used to perform an evaluation in accord with SATRA TM404:2020 – ‘Rapid sole adhesion test – for complete footwear’. While the footwear is still on its last, the sole is positioned on the ridge-shaped anvil (or fulcrum) so that the curved toe piece of the instrument fits in the featherline groove between the sole and the upper.
A gradually increasing force is applied by hand to the backpart of the footwear and this effectively becomes a downward force applied by the toe piece to separate the sole from the upper. This force is shown by the load dial gauge on the instrument, which incorporates a maximum load pointer.
The actual load necessary to cause separation can be measured. Alternatively, a pass load can be applied to check that the sole adhesion is satisfactory and the sole does not part from the upper assembly. This second method of operation is the more useful one in the shoe factory, since it can be applied to ordinary shoes from the production line.
If (as should happen) the sole remains securely attached, the shoes can be returned to the rack or track quite undamaged. However, if a sole pulls away before the pass load is reached, a check on materials, technique or production process should be made.
Testing heel bond strength
The measurement of adhesion at the heel (mainly for men’s shoes and industrial footwear) is carried out in a similar way. However, for this assessment, the heel is supported in an STD 185H heel attachment, which replaces the anvil (see figure 2). The STD 185H attachment is simple to attach to the STD 185 tester and it can be left in place while evaluating a toe bond.
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This article was originally published on page 34 of the September 2022 issue of SATRA Bulletin.