ASTM D 1056 Material Standard Explained

25 Nov 2020 | Posted by Andrew Onions

ASTM D 1056 Material Standard Explained

ASTM D1056 is a standard specification for Flexible Cellular materials specifically Sponge or Expanded Rubber. Flexible Cellular materials are typically categorized as Sponge being Open Cell and Expanded as Closed Cell.

Within the standard products are identified by a three-character Grade Number (eg: 2A2). These three characters represent Type, Class and Grade.

Material Types

The specification covers two types of cellular rubber designated by the prefix numbers 1 and 2

Type 1 = Open Cell Rubber
Type 2 = Closed Cell Rubber

Classes

Both types are divided into four classes, designated by the letters A, B, C, and D

• Class A = Cellular rubber made from synthetic rubber, natural rubber, reclaimed rubber, or rubber-like materials, alone or in combination, where specific resistance to the action of petroleum base oils is not required.  MacLellan product  P585 complies.
• Class B = Cellular rubber made from synthetic rubber or rubber-like materials alone or in combination, having specific requirements for oil resistance with low mass change.   MacLellan product Expanded Nitrile Sponge complies.
• Class C = Cellular rubber made from synthetic rubber or rubber-like materials alone or in combination, having specific requirements for oil resistance with medium mass change.  MacLellan product P580 complies.
• Class D = Cellular rubber made from synthetic rubber or rubber-like materials alone or in combination having specific requirements for extreme temperature resistance -103 to 347°F (-75 to 175°C): but specific resistance to the action of petroleum-base oils is not required.

Grades

Each type and class has then been divided into five different grades.

Each grade is based on specific range of firmness as expressed by compression-deflection. Grades are designated by a digit; the softer grades being identified with lower numbers and the firmer grades being identified with the higher numbers.

Suffix Letter Test Required

Materials properties are more accurately defined by the suffix letters, which relate to specific material performance requirements. 

A, Heat resistance
B, Compression set (B1 for 1A, 1B, and 1C only) (B2 & B3 for 2A, 2B, 2C, 2D only)
C, Ozone or weather resistance

D, Load deflection
E, Fluid resistance
F, Low-temperature resistance

G, Tear resistance
J, Abrasion resistance
K, Adhesion capability

L, Water absorption
M, Combustion characteristics
N, Impact resistance

P, Staining resistance
R, Resilience
T, Tensile/Elongation

W, Density
Z, Special requirements

Suffix numbers that follow the suffix letter denote different testing parameters or conditions for that suffix.

Eg. B1 stands for Compression Set at 70oC (158oF) and

B2 stands for Compression Set at 23oC (74.3oF) or Room Temp.

Example Line Call Out for Sponge ASTM D-1056 2C2 A1 B2 E1 Z (where Z = material passes FMVSS 302)

2 – Closed Cell,
C – Medium Oil Swell or Medium Oil Resistance
2 – Compression Deflection (25% Compression) 5 to 9psi,
A1 – Change in Compression Deflection after ageing for 22h at 100°C to be +/-30% from Original C.D.,
B2 – Compression Set at 23°C for 22h (50% compression) and after 24h recovery to be max. of 25%,
E1 – Test method and values to be arranged by the Purchaser and the Supplier
Z = States special requirement as detailed.

Comparative Standards

ASTM D1056 has been produced with reference to many other standards, bringing test methods up to date and aligning the performance criteria with modern day materials. Similar test standards that may be used within the market are:

MIL-C -3133 - The same as D 1056 and was discontinued in 1986.

SAE J18 - The same as D 1056, discontinued.

ASTM D1667 - Very similar to 1056. Specifically for PVC containing closed cell foams.

ASTM D3575 - Similar to 1056 for polyolefin foams. Plastics like polyethylene and ethylene vinyl acetate.