![]() ![]() Now we have it in our museum at Elastocon. I worked at SP between 1978 to 1989 and used this tester. This instrument was earlier very common in the rubber laboratories. The IRHD hardness method was standardised very early and have the number ISO 48. This is valid for natural rubber but may differ for other rubber polymers. The IRHD hardness tester was designed to show values equivalent to the Shore A scale. Compared to the Shore instrument using a spring, originally handheld and a measuring time originally specified to within 1 s. To get a more accurate result a constant load is used, the instrument is mounted on a stand and the measuring time is 30 s. The IRHD hardness instrument was developed to get a more accurate reading of rubber hardness than the Shore durometer. ![]() The table where the test piece is placed is vibrating to eliminate eventual friction in the instrument. The total stroke is 2,5 mm, so if the indenter is pressed 1,25 mm into the test piece, the instrument shows a hardness of 50 IRHD. The instrument measures Rubber hardness by measuring the indentation of a ball with the diameter of 2,5 mm pressed into the rubber. The hardness tester also has dial gauges for the scales IRHD-L and IRHD-H with corresponding indenters. The hardness test consists in measuring the differ- ence between the depths of indentation of a ball into the rubber under a small contact force and a large. They estimated the manufacturing to mid-60-ies. When asking Wallace about the manufacturing year, they replied that they never seen a photo of such an old instrument. It was manufactured by Wallace Co, UK, in the mid-60-ies. ![]() The relationship between the depth of penetration (hardness) and the IRHD number is based on:ĭ is the depth of penetration in mm.This is a hardness tester for the International Hardness Degree scale normal, IRHD-N. Based on the advantages of the TMA method, a further review of indentation instrumentation is provided. Is related to the depth of indentor penetration.įor highly elastic materials, IRHD and Shore A are comparable.Īn IRHD value of 0 represents a material with an Young's Modulus of zero and an IRHD value of 100 represents a material with an infinite Young's Modulus. Degree (IRHD), Shore A/D IS0 Ball, and Rockwell. The force is increased to a specified total load and the depth of penetration is measured. IRHD: International Rubber Hardness DegreesĪ measure of the indentation resistance of elastomeric or rubber materials based on the depth of penetration of a ball indentor.Īn initial contact force is applied to an indentor and the penetration is set to zero. Access over 120,000 technical material datasheets with Prospector! Create Your Free Account IRHD Hardness - ISO 48 ![]()
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