제목	Shore Hardness Properties
등록자	관리자	등록일	2016-01-06
Hardness test By definition, the Shore hardness is theresistance to penetration by a needle of defined shape under a defined load. Typical, Shore A is measured using a sharpneedle where as Shore D is measured with a rounded needle. Moreover, Shore A is selected for soft polymersup to 90 Shore A; harder polymers above 90 Shore A are measured using the ShoreD gauge. Although, it must been said that this rule isnot strictly followed on the published data sheets. Basically, most hardness measurements are in Europe either tested according ASTM 2240, DIN 53505 or ISO 868 test method. However, these test norms show a substantial difference regarding the selected time before the reading is taken. See table 1 Lubrizol measures the Shore hardness according ISO 868 but the time interval is 3 seconds. It is obvious that Shore hardness testing according ASTM D2240 and ISO 868 / 1 second reading results in higher values. Depending on the elasticity of the polymer, Shore A and D hardness value differences up to 5 points may appear between 1 and 3 seconds reading; Shore D shows a fast value drop when the time exceeds 1 second. A mathematical relation is used to convert the displacement data into hardness number, limited within range of 0 to 100. A and D are the two most commonly used scales. The sample thickness should be at least 6.0 mm.

제목

Shore Hardness Properties

등록자

관리자

등록일

2016-01-06

Hardness test

By definition, the Shore hardness is theresistance to penetration by a needle of defined shape under a defined load.

Typical, Shore A is measured using a sharpneedle where as Shore D is measured with a rounded needle.

Moreover, Shore A is selected for soft polymersup to 90 Shore A; harder polymers above 90 Shore A are measured using the ShoreD gauge.

Although, it must been said that this rule isnot strictly followed on the published data sheets.

Basically, most hardness measurements are in Europe either tested according ASTM 2240, DIN 53505 or ISO 868 test method.

However, these test norms show a substantial difference regarding the selected time before the reading is taken. See table 1

Lubrizol measures the Shore hardness according ISO 868 but the time interval is 3 seconds.

It is obvious that Shore hardness testing according ASTM D2240 and ISO 868 / 1 second reading results in higher values. Depending on the elasticity of the polymer, Shore A and D hardness value differences up to 5 points may appear between 1 and 3 seconds reading; Shore D shows a fast value drop when the time exceeds 1 second.

A mathematical relation is used to convert the displacement data into hardness number, limited within range of 0 to 100. A and D are the two most commonly used scales. The sample thickness should be at least 6.0 mm.