SATRA Sole Bond Award

The SATRA Sole Bond programme, which leads to the SATRA Sole Bond Award, is designed to optimise the sole bonding process. SATRA best practice guidelines can improve quality and reduce returns.

by Austin Simmons

The sole bonding process comprises several critical operations, and a weakness or fault in one of them is likely to affect the final bond integrity. With sole adhesion failure being a major cause of footwear returns, the SATRA Sole Bond programme is intended to help members apply correct procedures and attention to detail at each stage of the bonding process.

The SATRA Sole Bond Award is a third-party certification scheme which is intended to improve the quality and durability of finished production by introducing best practice processes and procedures that are monitored regularly via a quality management system. The award covers all areas of soling adhesion processes from pre-production to mass assembly, including health and safety, environmental issues and training, and is applicable to all methods of manufacture. 

Companies meeting the requirements are able to use the SATRA Sole Bond logo to demonstrate added assurance of product quality when marketing their footwear to existing and potential customers – particularly with regard to the integrity of sole bonds.

The SATRA Sole Bond programme involves SATRA assessing current arrangements through an initial audit, and then where necessary, introducing detailed process control improvements and operator training for all stages of the shoe bonding operations. Once the new arrangements have been established and bonds verified by testing, SATRA will carry out a final audit to ensure that everything is operating correctly. The SATRA Sole Bond Award will then be presented to the successful company. The award is valid for one year, subject to continued bond integrity tests carried out at three monthly intervals by SATRA, and it can be renewed annually after a satisfactory surveillance audit by SATRA.

A typical SATRA Sole Bond programme
Adhesive and primer storage	Correct storage and distribution of adhesives, primers and associated chemicals, taking into account shelf life and batch traceability.
Adhesive and primer mixing	Identification of appropriate equipment to be used and procedures covering accuracy of component mix, and the control of mixing itself to ensure homogeneity.
Upper and soling preparation	Appropriate and correctly maintained equipment and operating instructions covering both the process and inspection criteria.
Adhesive application (where relevant)	Application procedures and equipment. Inspection criteria.
Adhesive drying	Operator instructions covering procedures, process settings and control parameters used to ensure correct drying levels. Equipment maintenance and process monitoring with appropriate charting of conditions within drying cabinets to ensure suitability and consistency of the process. Control and inspection procedures to ensure open time limits are complied with.
Adhesive activation	Appropriate adhesive activation procedures, based on pre-production tests. Control of adhesive temperature including cooling where appropriate.
Pressing	Operator procedures and regular checks on equipment, including uniformity of pressure distribution.
Assessment of sole bonds	Random samples to be taken daily from each track and tested for bond strength by toe adhesion tests and tensile tester peels.
Health and safety	Appropriate protective clothing, gloves, goggles, and other relevant PPE made available to operatives.
Environmental	Control and checks on emissions of solvent vapours.
Training	Operator training and records.

Publishing Data

This article was originally published on page 42 of the November 2017 issue of SATRA Bulletin.

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