Crocker, L E; Dean, G D; Tomlins, P E (2005) A method for predicting the perceived hardness of soft-touch elastomeric coatings and over-mouldings. NPL Report. DEPC-MPR 035

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Abstract

The perceived and physical hardness of surfaces play a key role in our assessment of product quality and performance expectation. Thin rubbery overmouldings are now commonly used to impart a soft ‘feel’ to consumer goods such as golf clubs and screwdriver handles to influence prospective purchasers.
In a recent study we demonstrated a very strong correlation between the perceived hardness of materials and that measured by an indentation method following the Shore A scale. The ASTM standard that describes the Shore hardness method emphasizes the need to make measurements in relatively thick samples, well away from edges to avoid any potential edge effects. Such ‘edge effects’ are usually unavoidable in over-moulded coatings. In this study we report an approach to predicting the Shore hardness of a limited range of carbon-filled thermoplastic elastomers for a number of different geometries that include such edge effects. This enables prediction of the effective ‘softness’ of products. Results were validated against Shore Hardness measurements.

Item Type:	Report/Guide (NPL Report)
NPL Report No.:	DEPC-MPR 035
Keywords:	viscoelastic, FEA, hypoelastic
Subjects:	Advanced Materials Advanced Materials > Biomaterials
Last Modified:	02 Feb 2018 13:16
URI:	http://eprintspublications.npl.co.uk/id/eprint/3339

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