What is Shore A Hardness of an elastomer? | News | JIOrings

- Categories : JIOrings

Because hardness matters too...

This is one of the most used scales for measuring the hardness of elastomers. Although it is not the only one, apart from scale A there are scales B, C, D, 0 and 00. Of these, the Shore D scale is also used to measure the hardness of harder elastomers.

The hardness of an elastomer represents its stiffness against moderate stress, such as those that it frequently subjected to in an application.

There are two methods for obtaining the hardness of O-rings and other seals:

Durometer

A durometer is an instrument with a frusto-conical tip that, on penetrating the elastomer, produces a reaction in the calibrated metal spring. When the Shore A durometer indicates readings of greater than 90°, the use of the Shore D durometer, which has a tapered tip and a stiffer spring, is recommended.

To ensure the correct use of this measurement tool, we at JIOrings recommend:

• Using the durometer on a flat, clean, polished surface.

• Measuring perpendicular to the durometer´s indenting foot.

• Repeating the test 3 times in a different place on the part/seal each time.

Due to its simplicity and convenience, the Shore hardness form of measurement is widely used as a production control. The use of IRHD hardness is recommended for the purpose of more exact classification or specification:

Macro IRHD

This durometer is designed to obtain hardness in all types of elastomers and plastics with a minimum thickness of 6 mm. The system consists of a stand with a testing table and a macro head designed to accommodate IRHD N, IRHD L, IRHD H and Shore inserts. The inserts feature 1, 2.5 and 5 mm diameter ball indenter and test loads from 2.65 to 5.70 N.

Micro IRHD

A micro durometer is used to obtain hardness in all types of elastomers and plastics with a maximum thickness of 5 mm. The system consists of a stand with a testing table and a micro head with a 0.395 mm diameter ball indenter and test loads from 8.3 mN to 153.3 mN. The measurement stroke is 0.3 mm and the range is between 30 and 100 micro IRHD.

Hardness equivalence table

Shore A	IRHD	Shore D	Shore 0	Shore 00
DIN 53505	ASTM D 1415	DIN 53505	ASTM D 2240	ASTM D 2240
Compact and cellular elastomers	Compact elastomers	Polyurethanes, rigid PTFE, thermoplastics and very hard elastomers	Medium density compact and cellular elastomers	Medium and low density cellular elastomers
100	100	58
95	95	46
90	90	39
85	85	33
80	80	29	84	98
75	74	25	79	97
70	68	22	75	95
65	64	19	72	94
60	62	16	69	93
55	54	14	65	91
50	49	12	61	90
45	44	10	57	88
40	39	8	53	86
35	35	7	48	83
30	28	6	42	80
25			35	76
20			28	70
15			21	62
10			14	55
5			8	45