SATRA STM 567 Endofoot

SATRA’s Endofoot advanced test machine for determining footwear thermal performance & moisture management capability.

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SATRA STM 567 Endofoot (for advanced moisture management testing – AMMT)

This advanced test machine allows two footwear characteristics to be determined. The first characteristic which can be assessed is footwear thermal insulation, the second being sweat management inside the footwear.

Thermal insulation defines the footwear’s ability to protect the foot and maintain comfort when the user is operating in a cold environment. This is of particular interest, for example, to suppliers of cold weather active wear or the military.

The interior of a shoe, while in use, is a warm and humid environment in which moisture is present either from an external source or, more commonly, from sweat. The response of the footwear to the internal moisture, both long term and short term, is an important characteristic which affects comfort as well as insulation against cold.

Although internal moisture management and thermal performance of footwear may seem to be unconnected, there is an important relationship between footwear internal moisture and the ability of the footwear to maintain its insulation efficiency. An important characteristic of most insulation materials is trapped air pockets which provide a barrier to heat transmission. If the trapped air is replaced by moisture, which is a much better conductor of heat than air, then heat loss increases and the insulation properties of the footwear can be significantly degraded.

The SATRA STM 567 Endofoot machine allows both moisture management and thermal efficiency for footwear to be determined. The test is a whole shoe test, so whether conducting a thermal test or a moisture management test, the effect of sole, upper and lining, in addition to features such as seams and different types of hosiery are taken into account.

At the heart of the machine is a moulded foot form which incorporates electrical heating elements and a distribution system of small bore pipes, allowing water to be introduced through surface pores of the foot form to simulate sweat.

The SATRA TM386 test method (conducted using the SATRA STM 567 test machine) determines the thermal properties (insulation) of footwear. Whether to ensure that everyday shoes do not feel too hot, or to ensure specialist footwear, designed for use in sub-zero conditions, protects the foot from cold and provides acceptable comfort in these conditions. The test yields a measure of the energy needed to maintain the foot form at a uniform temperature. This is used to assess the thermal performance of the footwear. For example, a high energy usage indicates poor thermal insulation. SATRA has developed guideline values for this test, which we are happy to discuss with members. The guideline values allow footwear to be assessed for the particular environmental conditions for which the footwear is intended.

Another test method – SATRA TM376 – which is conducted using the SATRA STM 567 test machine, allows the moisture management capability of footwear to be assessed.

Footwear which has the capability of high levels of moisture absorption will aid short-term foot comfort, even if the overall shoe system has low permeability. For longer-term foot comfort, high permeability together with good desorption are usually necessary. Thus, the ability of the footwear to breathe and release moisture to the environment is a vital part of longer-term comfort. As previously discussed, the amount of moisture retained within the footwear also affects the footwear’s insulation properties. When conducting a moisture management test, SATRA TM376 defines test duration, sweat rates and foot form temperatures. These parameters are adjustable to match footwear use conditions.

The SATRA STM 567 Endofoot machine is a versatile machine allowing thermal efficiency to be assessed, either with a dry foot form or with moisture present (representing sweat), as well as assessing the ability of the footwear to absorb moisture (sweat) internally and release moisture to the environment (breathability). The machine can also be used to evaluate alternative hose systems, applied with footwear, with respect to their moisture management ability and insulation properties.

Output from tests utilising the Endofoot machine can be used to improve footwear sweat management. Another developing role for the STM 567 test machine is its use to determine footwear ‘cold rating’. Cold rating is a measure of the long-term ability of footwear to protect the foot from extreme environments. Tests conducted using the SATRA STM 567 machine can assist in the development of a wide range of shoe types, including sports, cold weather active wear, military applications and industrial, as well as everyday fashion shoes.

If you would like to find out more about the SATRA STM 567 Endofoot machine or obtain a quotation, please contact James Corton.

If you would like to discuss how this machine could contribute to your own product development: establishing thermal efficiency; carrying out a cold rating assessment or confirming moisture management capability, please contact James Corton.