Description / Abstract: Material Description. This standard covers static sealing O-rings used in gas, hybrid, and diesel engine oils. It outlines the recommended types of materials and applications (Table 1). The second section provides longer term qualifications for approving each source/material type (Table 2) and the final section (Table 3) provides a standard content template for all prints/drawing using part properties where size permits. The print property template allows GM Powertrain to reinforce and standardize the desired material properties related to functional needs and actual part data for quality control.

This standard does not supercede GMW standards already containing O-ring requirements. See remarks in 1.4 through 1.4.2.

Symbols. O-rings may be marked to designate the type of material and/or source from which the part was fabricated for the purpose of traceability and sorting. Surface etching by Light Amplification by Stimulated Emission of Radiation (LASER) and imbedded chips are used for assembly verification. Colored compounds also improve sorting.

Applicability.

Use the initial compound requirements defined in Table 2 to qualify all candidate compounds. Basic SAE J200M/ASTM D2000M classifications using slab or sheet form are only applied to O-rings too small or large (see 1.4) with properties to failure that cannot be measured before reaching the maximum travel limits of the tensile test machine.

Use the Table 3 template for O-ring prints with data from the production intent part described on that drawing. If the as received production part size does not permit testing, use the Table 2 properties and data will be the default.

Establish production part state of cure using compression set (see 3.5.8).

This standard supports engine material bill of requirements for oil (Table 1) using material types recommended for that media.

Remarks. The compound properties for each type of elastomer are listed in Table 2 and Table 3. Table 2 (values) and Table 1 (class and type) are a compilation of data from multiple approved compounds and hardness ranges (50 Shore A to 80 Shore A) using the SAE AS568D-214 size O-ring (Inside Diameter (ID) 25 mm × 3.5 mm cross section). Table 3 properties are generated to represent one production part compound from print dimensions. Table 3 results are placed on the part print using data from the production part.

Functional Noun Name. GM prints use O-ring to describe any circular shaped, press-in-place gasket even though the cross section is not circular. The part print functional name may not include O-ring in the drawing title block even if it is a toroid shape. Regardless of the GM Functional Name Assignment (FNA) convention, this standard is used exclusively for elastomer O-rings with a toroid (circular) cross section.

Fluorocarbon Behavior in Fuel Diluted Oil. For methanol and ethanol diluted oil conditions, the percent fluorine level (higher is desired) is most important. In biodiesel diluted conditions with oil, the cure type (peroxide) and no metal oxides, take precedence over percent fluorine. The metal oxides have no significant impact on fluorocarbon (FKM) Type II, III, IV or V peroxide cure systems. There is no impact on color choice for carbon black filled and mineral filled systems. There are variations in naming conventions for metal oxides. For example, ceramic type mineral systems are metal oxides and are being used successfully in mobility systems where zinc, calcium or magnesium oxides would not be successful in that application.