MatWeb - Material Property Data Advertise with MatWeb!     Register Now
Data sheets for over 105,000 metals, plastics, ceramics, and composites.
MatWeb - Material Property Data HOME  •   SEARCH  •   TOOLS  •   SUPPLIERS  •   FOLDERS  •   ABOUT US  •   FAQ  •   LOG IN    
Recently Viewed Materials (most recent at top)  

Login to see your most recently viewed materials here.

Or if you don't have an account with us yet, then click here to register.

  Searches:   Advanced  | Category  | Property  | Metals  | Trade Name  | Manufacturer  | Recently Viewed Materials
  

Shore (Durometer) Hardness Testing of Plastics

The hardness of plastics is most commonly measured by the Shore® (Durometer) test or Rockwell hardness test. Both methods measure the resistance of plastics toward indentation and provide an empirical hardness value that doesn't necessarily correlate well to other properties or fundamental characteristics. Shore Hardness, using either the Shore A or Shore D scale, is the preferred method for rubbers/elastomers and is also commonly used for 'softer' plastics such as polyolefins, fluoropolymers, and vinyls. The Shore A scale is used for 'softer' rubbers while the Shore D scale is used for 'harder' ones. Many other Shore hardness scales, such as Shore O and Shore H hardness, exist but are only rarely encountered by most people in the plastics industry.

The Shore hardness is measured with an apparatus known as a Durometer and consequently is also known as 'Durometer hardness'. The hardness value is determined by the penetration of the Durometer indenter foot into the sample. Because of the resilience of rubbers and plastics, the indentation reading my change over time - so the indentation time is sometimes reported along with the hardness number. The ASTM test method designation is ASTM D2240 00 and is generally used in North America. Related methods include ISO 7619 and ISO 868; DIN 53505; and JIS K 6301, which was discontinued and superceeded by JIS K 6253.

The results obtained from this test are a useful measure of relative resistance to indentation of various grades of polymers. However, the Shore Durometer hardness test does not serve well as a predictor of other properties such as strength or resistance to scratches, abrasion, or wear, and should not be used alone for product design specifications. Shore hardness is often used as a proxy for flexibility (flexural modulus) for the specification of elastomers. The correlation between Shore hardness and flexibility holds for similar materials, especially within a series of grades from the same product line, but this is an empirical and not a fundamental relationship.

As seen in the charts below, the correlation between the two Shore Durometer hardness scales is weak; attempts at conversion between the scales are therefore discouraged. The correlation is higher for materials with similar resiliency properties, but is still too low for reliable conversions. Likewise, conversion between Shore Hardness and Rockwell hardness is discouraged.

The charts below are taken from data in MatWeb's database provided by polymer manufacturers for specific product grades.

Comparison of Shore Hardness Scales

Chart of Shore A vs. Shore D Hardness

Chart of Shore A vs. Shore D Hardness for Polyolefins

Chart of Shore D vs. Rockwell M Hardness

Chart of Shore D vs. Rockwell R Hardness

Other hardness topics in MatWeb:

Shore® is a registered tradename of Instron Corporation.
Please read our License Agreement regarding materials data and our Privacy Policy. Questions or comments about MatWeb? Please contact us at webmaster@matweb.com. We appreciate your input.

The contents of this web site, the MatWeb logo, and "MatWeb" are Copyright 1996-2014 by MatWeb, LLC. MatWeb is intended for personal, non-commercial use. The contents, results, and technical data from this site may not be reproduced either electronically, photographically or substantively without permission from MatWeb, LLC.