ET-7403-03

EDS

E ngineering,

D aewoo motor co., ltd.

S tandards

DETERMINATION OF HARDNESS OF ELSTOMERIC

COMPONENTS

EDS-T-7403

ISSUED DATE: 1990. 08. 10

REVISED D ATE: 1997. 07. 25

VERSION: 3

Copyright Daewoo Motor Co., Ltd. All rights reserved

EDS-T-7403

DETERMINATION OF HARDNESS OF

ELSTOMERIC COMPONENTS PAGE: 1/4

1. PURPOSE

The purpose of this standard is to determine the indentation hardness of vulcanized elastomers and plastic components.

2. SCOPE

Unless otherwise specified, the hardness shall be determined according to one way of clause 2.1., 2.2. and determination to clause 2.2. made for precise results.

2.1. Spring Durometer : SHORE A, D

2.2. Micro Durometer (IRHD)

3. SPRING DUROMETER

3.1. Test pieces

3.1.1. The measured area of test piece shall be even but if not, it shall be grinded.

3.1.2. The test piece thickness shall be 6 mm min and the thinner material may be laminated to exceed 6 mm. 3.1.3. If the test pieces are laminated, air trapping between layers must be avoided.

3.1.

4. At least 3 points shall be measured at intervals of 5 mm apart 12 mm from any edge.

3.1.5. At least 3 test pieces shall be used.

3.1.6. If results is more than 90 when measured with shore A, shore D shall be used.

3.2. Conditioning

3.2.1. For initial sample approval and arbitration purposes, tests shall not be conducted earlier than 7 days after vulcanization (for plastics, molding) and for routine quality control, not earlier than 3 days.

3.2.2. The elastomeric test pieces shall be stored for at least 8 hours at 23±5?, free from strain before test.

3.2.3. The plastic test pieces shall be stored for at least 16 hours at 23±5?, 50% relative humidity, free from strain before test.

3.3. Test apparatus

3.3.1. Test apparatus shall be used spring type Durometer (Shore A, D) It shall indicate the distance for needle supported by spring pressure from the hole in the middle of pressurizing area to return, pressed by elastomeric surface when pressurizing area of test machine contact on surface of test piece

3.3.2. The pressurizing area shall be vertical plane to pressing area, have the middle hole which the needle can pass through as Figure 1. and more than 10 mm wide.

EDS-T-7403

DETERMINATION OF HARDNESS OF

ELSTOMERIC COMPONENTS PAGE: 2/4

3.3.3. The material of pressing needle shall not be worn away and get rusty. The shape and dimensions shall be same as Figure 1. and the needle adhered rightly to the middle of the pressurizing area.

3.3.

4. The end of the needle shall be on the same plane as pressurizing plane when an arrow indicate degree of 100.

3.3.5. The interval of degrees between 0 and 100 shall be same.

3.3.6. The test machine shall be inspected every year by authorized agencies.

3.4. Procedure

3.4.1. Tests shall be normally performed at 23±5?. In case drawings and materials specifications demand measurement at low temperature, the hardness tester shall be left inside a cool chamber for more than 30 minutes to reach the test temperature.

3.4.2. The pressurizing area of durometer shall be vertical to the measuring area of test piece and pressurize in contact with full area.

3.4.3. The tolerance of ±3 shall be permitted when the durometer is used by hand and the tolerance of ±1, when the stand-fixed durometer is used.

3.4.4. Read the value of degree 3 seconds after the pressurizing area is in contact with the test piece. In case the specimen has flow characteristics, however, read the value of degree after 15 seconds is elasped.

3.5. Test results

The hardness shall be determined as middle value after 3 points measured e.g.) The result is 54 when 52, 54,

57 are measured.

4. BALL INDENTATION (IRHD) HARDNESS TEST

4.1. Test pieces

4.1.1. The standard test piece shall be 20×40 mm wide, 2±0.5 mm thick and the front and back area shall be flated.

4.1.2. For taking the test piece from component, it shall be at least 4x6mm wide and 1 mm thick. Normally test area shall be 4×20 mm and any coated test pieces shall be not used.

4.1.3. For taking the test piece from components such as o-ring or lip seal, it shall be at least 1.5 mm in diameter and at least 1mm thick. The test area shall maintain the interval of at least 0.75 mm from the edge and at least 3 points shall be measured.

4.1.4. At least 3 test pieces shall be used.

EDS-T-7403

DETERMINATION OF HARDNESS OF

ELSTOMERIC COMPONENTS PAGE: 3/4

Fig 1. Structure of Contact Area & Dimension.

a ?(3.00±0.10) mm d ?(0.79±0.01) mm

b ?(1.25±0.15) mm r (0.10±0.01) mm

+0.04

f ? (0.79±0.01) mm

c (2.50 ) mm

-0.01

4.2. Conditioning

Conditioning of test pieces is same as clause 3.2

4.3. Mounting of test piece

For special test pieces with curved surface such as lip seal, the test piece shall be mounted into non-union hardened material for the surface of test piece to level the test supports.

4.3.1. Polyester resin with special hardening such as aero-elastic resin shall be appropriate as hardened material.

4.3.2. When test piece is inserted into mounting material, care shall be taken that no bubbles occur from the bottom of test piece.

4.3.3. The test pieces where mounting is completed shall be stored at 23? for at least 2 hours.

4.3.4. Polishing shall be performed after grinding so that the test area gets smooth and flated.

EDS-T-7403

DETERMINATION OF HARDNESS OF

ELSTOMERIC COMPONENTS PAGE: 4/4

4.4. Test apparatus

IRHD (CARL FRANK GMBH TYPE 38209) shall be used.(Refer to D-EDS-PST-099 (DWMC standard))

4.5. Procedure

4.5.1. Normally tests shall be performed at 23±5?.

4.5.2. The test pieces shall be placed horizontally on measuring table, the pressurizing area vertically in contact with the test surface and subjected to initial force for 5 seconds.

4.5.3. The arrow shall be set to 100 degree.

4.5.4. The test force shall be applied to the test piece for 30 seconds.

4.5.5. Read the degree indicated by arrow when buzzer rings after 30 seconds.

4.6. At least 3 test pieces shall be tested and the results shall be the median.

5. CODING SYSTEM

Hardness test EDS-T-7403 IRHD

Designation Specification and Test method Test results specification

6. DEVIATIONS

Deviations from the conditions of this method (conditioning number of test pieces etc.) shall have been agreed upon. These shall be specified on drawings, material specifications and must be indicated in test certificates, reports etc..

7. REFERENCE

ASTM D2240 DUROMETER HARDNESS

ASTM D1415 INTERNATIONAL HARDNESS

DIN 53519 INDENTATION HARDNESS

DIN 53505 TESTING OF ELASTOMERS SHORE A AND D HARDNESS TESTING

DWMC STANDARD D-EDS-PST-009