Durometer hardness test

Duriron Duromer Durometer hardness test Duroquin Duro Sup er Glue Duro-Tak... 

Durometer. The Durometer hardness test was developed for and is used for determining the hardness of elastomers. The Durometer is a hand-held, spring-loaded instrument which when pressed against the sample forces a conical steel indenter into the surface. Durometer hardness numbers range from 0 to 100 and are read directly from the attached dial indicator. Several load scales are available, but the A scale (8 N = 822 gf) and the D scale (44.5 N = 4.54 kgf) are most common. Specifics of the test procedure are discussed in ASTM D2240 (2). Lighter load scales and larger diameter indenters are available for very soft materials such as foam. 

Hardness is defined as the resistance of a material to deformation, particularly permanent deformation, indentation or scratching. Hardness is purely a relative term and should not be confused with wear and abrasion resistance of plastics. For example, polystyrene has a high hardness but a poor abrasion resistance. Many tests have been devised to measure hardness. However, Rockwell and Durometer hardness tests are commonly used. The Rockwell hardness test measures the net increase in depth impression as the load on an indentor is increased from a fixed minor load to a major load and then returned to a minor load. The hardness numbers derived are just numbers without units. Rockwell hardness numbers in increasing order of hardness are R, L, M, E and K scales. The higher the number in each scale, the harder is the material. The Durometer hardness test is based on the penetration of a specified indentor forced into... 

LDPE is easily marked by a thumbnail, HOPE is scratched in this way with difficulty, but PP is marked little, if at all. Hardness is defined as the resistance of a material to deformation, particularly permanent deformation, indentation, or scratching. Hardness is a relative term and should not be confused with wear and abrasion resistance. Many tests have been devised to measure hardness. Rockwell and Durometer hardness test are commonly used. 

The Durometer hardness test is used for measuring the relative hardness of soft materials. The test method is based on the penetration of a specified indentor forced into the material under specified conditions. 

Durometer hardness testing determines the resistance of the sample to penetration by an indentor, which is a spring-loaded point initially protruding 1 mm from a flat surface. The profile of the indentor and the elastic constant of the spring to which it is attached define the type of durometer. In the case of polyethylene, durometer Type D is commonly used. When the flat surface is brought into firm contact with a block of polymer (minimum thickness 6.35 mm), the depth to which the indentor penetrates the specimen is inversely proportional to its hardness. After a fixed interval of time (commonly 10 secs), the hardness, in arbitrary units, is read directly from the scale. 

The radiation and temperature dependent mechanical properties of viscoelastic materials (modulus and loss) are of great interest throughout the plastics, polymer, and rubber from initial design to routine production. There are a number of laboratory research instruments are available to determine these properties. All these hardness tests conducted on polymeric materials involve the penetration of the sample under consideration by loaded spheres or other geometric shapes [1]. Most of these tests are to some extent arbitrary because the penetration of an indenter into viscoelastic material increases with time. For example, standard durometer test (the "Shore A") is widely used to measure the static "hardness" or resistance to indentation. However, it does not measure basic material properties, and its results depend on the specimen geometry (it is difficult to make available the identity of the initial position of the devices on cylinder or spherical surfaces while measuring) and test conditions, and some arbitrary time must be selected to compare different materials. 

Recommended Practice for Scleroscopic Hardness Testing of Metallic Materials Test Method for Rubber Property International Hardness Test Method for Rubber Property Durometer Hardness... 

International Rubber Hardness. The International mbber hardness test (ASTM D1415) (2) for elastomers is similar to the Rockwell test ia that the measured property is the difference ia penetration of a standard steel ball between minor and major loads. The viscoelastic properties of elastomers require that a load appHcation time, usually 30 seconds, be a part of the test procedure. The hardness number is read directly on a scale of 0 to 100 upon return to the minor load. International mbber hardness numbers are often considered equivalent to Durometer hardness numbers but differences ia iadenters, loads, and test time preclude such a relationship. 

Vickers and Knoop indentors, Barcol hardness, and Shore durometers (2) (b) to measure the resistance of a material to scratching by another material or by a sharp point, such as the Bierbaum hardness or scratch-resistance test and the Moh one for hardness and (c) to measure rebound efficiency or resilience, such as the various Rockwell hardness tests. The various tests provide different behavior characteristics for plastics, as described by different ASTM standards such as D 785. The ASTM and other sources provide different degrees of comparison for some of these tests. 

Figure 7-10 shows durometer scale relationships and hardness ranges. The letter designations refer to the Shore hardness test (Chapter 5, MECHANICAL PROPERTY, Hardness). 

The shore durometer is a simple instrument used to measure the resistance of a material to the penetration of a blunt needle. In the Barcol approach, a sharp indentor is used to measure the ability of a sample to resist penetration by the indentor (Figure 14.18). The values given in Table 14.3 are for one specific set of conditions and needle area for the Barcol and Brinell hardness tests. 

Durometer hardness - A value that indicates the indentation or resistance to indentation of the indentor point of a durometer. High values indicate harder materials. See ASTM D2280-Test Method for Rubber Property-durometer Hardness. 

Durometer Test Method for Rubber Property Durometer Hardness D2240... 

The standard briefly covers the significance of hardness in terms of its relation with modulus, and the practical use of hardness tests. The hardness tests for rubber that are standardized by ISO are introduced and the distinction between dead load and durometer type instruments is explained to help with selection of a test method for particular circumstances. The effect of test piece, use of standard hardness blocks and comparison of hardness scales is also outlined. 

The particular case of the hardness of rollers is covered by ISO 726734 36 which is in three parts dealing with the normal dead load method, Shore durometer and the Pusey Jones methods respectively. This last method is a very old hardness test which is now virtually never seen, although it is understood to still be popular in some circles for rollers. It is an amazing brass and chain contraption that uses a 3.175 mm indentor acting under a load of 1kg and without a surrounding foot. 

Hardness tests attract more interest in their accuracy, reproducibiliy and intercomparison than any other test - which is probably a result of them being simple tests which are carried out particularly frequently, and because the situation is confused with several scales. The fact that the situation is far from clear cut owes as much to history as to logic. If the Shore durometers had not been the first hardness meters, it is highly doubtful that we would now have spring loaded instruments mounted on stands or use damage prone indentors. Neither would the IRHD scale have been contrived to mimic the status quo. Such is the effect of powerful established interests. 

Standard test method for rubber property Durometer hardness Shore A and Shore D hardness testing of rubber Physical testing of rubber Part A57... 

Test method for indentation hardness of rubbers, international hardness Test for Durometer hardness of rubbers... 

Blend of ingredients is tested for cure characteristics molded testpiece is tested for common attributes such as durometer hardness, specific gravity, percentage ash, IR spectrum of pyrolizate, and UVspectrum of an aqueous extract. 

Durometer hardness is measured on tests specimens that meet specific standards for shape and thickness. Durometer hardness is usually measured using the Shore A scale, which measures relative hardness on a scale of 0 to 100 units. Most rubber components for medical use are found in the 35-60 range with 40-50 typical for rubber vial stoppers. Durometer Hardness may be measured on some actual components if they have a sufficiently large flat surface and thickness, i.e., 28-32 mm IV stoppers. 

Standard Test Method for Rubber Properties Durometer Hardness, ASTM D2240-97el, ASTM West Consho-hocken, PA, 1999. 

ASTM D 2240-86 Standard Test Method for Rubber Property — Durometer Hardness, 5 pp (DOD Adopted) (FSC 9320) (MR) (Comm D-11)... 

Mechanical Tests. Hardness measurements taken with a Shore A durometer are reported every time a pad specimen has been removed from its water bath for compression-deflection tests. Separate flat slabs, 0.12 and 0.50 in. thick, of polyurethane elastomer, which were cast from the same batch of material and given identical exposure to water as the pads, were employed for the hardness tests. 

The standard test method for measuring the durometer hardness of rubbers according to ASTM D2240-05 [6] is based on the penetration of a specified indentor forced into the material under specified conditions. The indentation hardness is inversely related to the penetration and is dependent on the elastic modulus and viscoelastic behaviour of the material. This method is an empirical test intended primarily for control purposes. No simple relationship exists between indentation hardness determined by this method and any fundamental property of the material tested. 

D 2240 Standard Test Method for Rubber Property—Durometer Hardness... 

Standard test method for rubber property - Durometer hardness... 

The Lambda series of Medicaflex is a polyurethane-based TPE polymer that exhibits low modulus characteristics with high tear strength and abrasion resistance. Those listed in the tables have passed USP Class VI compatibility tests and have been used as replacements in some natural rubber latex and silicone rubber applications. The polymer has been applied to uses such as catheters, tubing and films where softness, low durometer hardness, low modulus or high elongation are needed (Tables 4.3, 4.12, and 4.13). 

D 1790 Test method for Brittleness Temperature of Plastic Film by Impact D 1938 Test method for Tear Propagation Resistance of Plastic Film and Thin Sheeting by a Single-Tear Method D 2240 Test Method for Rubber Property - Durometer Hardness D 2702 Standard Practice for Rubber Chemicals - Determination of Infrared Absorption Characteristics... 

---