SATRA devices for better heat setting

Equipment that can help shoemakers to gain the best possible results from their heat setting process.

The article ‘Effective heat setting for footwear’ describes how the process is used correctly for the most successful results. As mentioned, SATRA produces two important devices that can help footwear manufacturers to achieve the best outcome from their heat setting equipment.

SATRA Sensor

The SATRA STD 228 Sensor (figure 1) is a small data logger, which is robust, very easy to use and capable of giving many years of use. SATRA Sensor reacts quickly to changes in conditions and takes temperature and humidity readings every half second. Although the SATRA Sensor is small in size, it is best mounted in the specially-engineered last that is supplied, as this gives the conditions at the cone of the last which are created during normal production. It is influenced by last temperature – just as the footwear is – and gives a true reading of the heat setting conditions experienced by the product.

At the end of the run, the data is simply downloaded to a PC via a USB connection and a full moisture, temperature and time profile of the machine can be seen. It is generally easy to then adjust the machine to give the required profile. Even the time the product spends in the required conditions can be measured. The ‘curtains’ (seals) often leak, meaning that the correct conditions are not met until the product is well inside the machine. SATRA Sensor is also adept at identifying the existence of faults in the machine – a valuable ability as the condition and maintenance of the machine are key to the quality of the final product.

When conditions are correct and are giving the best results, SATRA Sensor can be used to ‘copy’ conditions from one machine to another within a factory. This data can even be emailed to another part of the world to ensure that all the heat setters for a specific style are functioning to the same specification.

Dome plastimeter

The SATRA STD 449 dome plastimeter (figure 2) can be used to achieve the best set and is sensitive enough to rectify problems with difficult materials. STM 449 is a low-profile device that simulates a demanding set situation. It is easily used with combined upper materials to simulate the lasted upper. A small, circular specimen of the upper material is clamped into a metal former and then shaped by increasing the height of a dome to replicate the extension process that occurs during lasting.

The device is then passed through the heat setter, ideally at the same time as SATRA Sensor monitors and records the conditions. At the end of the process, the dome is released, thus removing the strain from the specimen. The height of the specimen is then recorded. After a set period of time, this can be re-measured and the amount of set determined. A good leather should retain 70 per cent of its set using this method, and adjustments can be made to the machinery and process should this figure fall short.

Publishing Data

This article was originally published on page 44 of the April 2015 issue of SATRA Bulletin.

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