Improved sole bonding with SATRAFoil

The use of SATRAFoil is a convenient technique for assessing sole bonding processes.

Important to good sole bonding is the application of a uniform pressure. SATRAFoil has been developed to assist manufacturers to apply an even pressure during the cemented construction sole bonding process. It is an embossed aluminium foil, developed and manufactured by SATRA, which is designed so that the embossing collapses when appropriate pressure is applied.

SATRAFoil is easy to use and gives an immediate visual indication of the pressure distribution around the bonding margin. The foil is placed between the lasted upper and the sole (neither of which have had adhesive applied), and the assembly is put into a sole press. A pressing operation is then carried out, after which the footwear is removed and the SATRAFoil is inspected. The embossed dimples should have been pressed flat around the full periphery of the bonding margin. If sections in the foil are found to have not been flattened in the bonding margin, the last or the sole press should be inspected to identify and remedy the causes of uneven pressure at the positions indicated on the foil.

If the distribution of pressure is found to be even but the dimples in the SATRAFoil have not been flattened, the overall pressure is too low. After making adjustments to the pressure distribution or the overall pressure, a fresh section of SATRAFoil should be used to repeat the trial pressing to confirm the changes have achieved the desired effect, with the dimples around the full bonding margin being fully flattened.

Historically, poor sole bonding has been a major cause of footwear failure. SATRAFoil can be integrated into factory process control to help combat this problem, and can be obtained from SATRA’s test equipment sales department as a ‘quality consumable’.

Publishing Data

This article was originally published on page 16 of the January 2018 issue of SATRA Bulletin.

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