Shore Durometer - Wikipedia, The Free Encyclopedia
Shore Durometer - Wikipedia, The Free Encyclopedia
Shore Durometer - Wikipedia, The Free Encyclopedia
Shore durometer
From Wikipedia, the free encyclopedia
1 Durometer scales
2 Method of measurement
3 Relation between Shore hardness and elastic
modulus
4 Patents
5 See also
6 References
7 External links
Durometer scales
There are several scales of durometer, used for materials with different properties. The two most common
scales, using slightly different measurement systems, are the ASTM D2240 type A and type D scales. The A
scale is for softer plastics, while the D scale is for harder ones. However, the ASTM D2240-00 testing standard
calls for a total of 12 scales, depending on the intended use; types A, B, C, D, DO, E, M, O, OO, OOO,
OOO-S, and R. Each scale results in a value between 0 and 100, with higher values indicating a harder
material.[2]
Method of measurement
Durometer, like many other hardness tests, measures the depth of an indentation in the material created by a
given force on a standardized presser foot. This depth is dependent on the hardness of the material, its
viscoelastic properties, the shape of the presser foot, and the duration of the test. ASTM D2240 durometers
allows for a measurement of the initial hardness, or the indentation hardness after a given period of time. The
basic test requires applying the force in a consistent manner, without shock, and measuring the hardness (depth
of the indentation). If a timed hardness is desired, force is applied for the required time and then read. The
material under test should be a minimum of 6.4 mm (.25 inch) thick.[3]
Type A Hardened steel rod 1.1 mm - 1.4 mm diameter, with a truncated 0.822 8.064
35º cone, 0.79 mm diameter
Hardened steel rod 1.1 mm - 1.4 mm diameter, with a 30º
Type D 4.550 44.64
conical point, 0.1 mm radius tip
The final value of the hardness depends on the depth of the indenter after it has been applied for 15sec on the
material. If the indenter penetrates 2.54 mm (0.100 inch) or more into the material, the durometer is 0 for that
scale. If it does not penetrate at all, then the durometer is 100 for that scale. It is for this reason that multiple
scales exist. Durometer is a dimensionless quantity, and there is no simple relationship between a material's
durometer in one scale, and its durometer in any other scale, or by any other hardness test.[1]
where E is the Young's modulus in MPa and S is the Shore hardness. This relation gives a value of at
S = 100 but departs from experimental data for S < 40.
Another relation that fits the experimental data slightly better is[5]
Another linear relation between the Shore hardness and the Young's modulus is applicable over a large range of
Shore A and Shore D hardnesses[6]. This relation has the form
where S A is the Shore A hardness, S D is the Shore D hardness, and E is the Young's modulus in MPa.
Patents
US patent 1770045 (http://v3.espacenet.com/textdoc?DB=EPODOC&IDX=US1770045) , A.F.
Shore, "Apparatus for Measuring the Hardness of Materials", issued 1930-07-08
See also
Brinell hardness test
Bloom (test)
Hardness
Knoop hardness test
Leeb Rebound Hardness Test
Rockwell hardness test
Vickers hardness test
References
1. ^ a b "Shore (Durometer) Hardness Testing of Plastics" (http://www.matweb.com/reference/shore-
hardness.asp) . http://www.matweb.com/reference/shore-hardness.asp. Retrieved 2006-07-22.
2. ^ "Material Hardness" (http://www.calce.umd.edu/general/Facilities/Hardness_ad_.htm#3.5) . CALCE and the
University of Maryland. 2001. http://www.calce.umd.edu/general/Facilities/Hardness_ad_.htm#3.5. Retrieved
2006-07-22.
3. ^ a b "Rubber Hardness" (http://www.npl.co.uk/server.php?show=ConWebDoc.379) . National Physical
Laboratory, UK. 2006. http://www.npl.co.uk/server.php?show=ConWebDoc.379. Retrieved 2006-07-22.
4. ^ A.N. Gent, (1958), On the relation between indentation hardness and Young's modulus, International Rubber
Institute Transactions, 34 , pp. 46–57.
5. ^ British Standard 903, (1950,1957), Methods of testing vulcanised rubber Part 19 (1950) and Part A7 (1957).
6. ^ a b Qi, HJ and Joyce, K. and Boyce, MC, (2003), Durometer hardness and the stress-strain behavior of
elastomeric materials, Rubber Chemistry and Technology, 76(2), pp. 419-435.
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External links
Durometer reference guide (http://www.rexgauge.com/content/tech_reference_guide)
Durometer Hardness Scale Chart (http://www.plasticsintl.com/polyhardness.htm)
Durometer comparison chart (http://www.rexgauge.com/content/tech_comparison_chart)
Durometer range (http://www.worldoftest.com/bareissmain.htm)
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Categories: Dimensionless numbers | Hardness tests
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