SATRA releases revised TM83 test method
Announcing a revision to SATRA TM83 – ‘Measurement of the area shape retention and collapsing load of formed toe puff and stiffener material’.
SATRA TM83 is intended to determine the shape retention properties and compression strength of a domed test specimen. It is primarily applicable to footwear toe puff (box toe) and stiffener (counter) materials, but can also be used to assess any deformable material. However, the dome preparation methods have been found to be unsuitable for some types of modern materials.
For this reason, the SATRA TM83 test method has been revised to include and account for new material technology, thus ensuring that the SATRA method continues to be relevant for advanced modern materials, as well as more conventional materials used in the shoemaking industry.
For heat-activated materials, the original method (known as the ‘conventional oven method’) requires a fan-assisted oven and calibrated dome formers – as well as a manual or pneumatic press – for testing to begin. The fluidity of some modern materials means that it is difficult to form effective domes using this method.
A new method – known as the ‘flash activation formation method’ – has been developed that better suits the fluidity characteristics of modern sintered materials (a process of compacting and forming or shaping a solid mass of material by heat or pressure before then allowing it to cool, so that it forms in the desired shape. This has to be a quick process, otherwise it begins to flow away, as it is a viscous liquid).
The new method requires:
- the sample to be cut as per the original test method
- the sample then be heated under a flash activator until it reaches a temperature specified by the manufacturer
- the sample to then be placed centrally in the dome former before being put into a pneumatic press for a period of time, as specified by the manufacturer.
Testing in SATRA’s laboratories confirmed that the new formation method was considered to produce a good quality dome. This possessed good area shape retention, reproducibility across samples and initial dry collapsing loads, which were comparable to those produced by the conventional oven method.
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This article was originally published on page 42 of the October 2018 issue of SATRA Bulletin.