NAVISTAR - TMS 6039
Rubber (TSR) Molding Compounds
|Publication Date:||1 April 2006|
This specification covers the general requirements, identification, inspection, property and performance requirements, quality plan, and source approval and quality control requirements for these TSR compounds.
Rubber Compound Designation - Description
The TSR compounds covered in this specification may include several different types of polymer base, such as EPDM, NR, CSM, NBR, etc. Within each of these basic polymer groups, several different blends and curing treatments are available, and unless otherwise specified, may be used to provide the specified hardness and other material properties required for the part. A specific polymer may be specified within the material designation for the part. Upon approval of the prototype and/or PPAP samples, no changes in the polymer base, blend, curing treatment, or other processing variables shall be made without the approval of Materials Engineering and the Quality Department of the receiving plant.
All rubber molding compounds provided to the requirements of this specification shall be designated with the TSR prefix. A specific polymer may or may not be specified in the material designation. These materials may contain recycled rubber (post-consumer recycled material, such as automotive tires) with prior Engineering approval. If industrial recyclate (pre-consumer recycled material) is included in the TSR compound, it shall be reported separately from the post-consumer recycled content.
Additional requirements for parts made from the rubber molding compound may be specified by adding a suffix to the compound designation. The suffix requirement is in addition to the normal durometer hardness and tensile requirements of the material designation and independent of the polymer base used for the part. The suffix designation follows and is separated from the TSR prefix by a "dash'. In some cases more than one suffix requirement may be designated.
Suffix-H: This designates a heat- and weather-resistant TSR material. Unless otherwise specified on the Engineering drawing, product supplied shall meet the heat resistance and aged heat adhesion requirements as specified in Tables 4-9. Minimal oil resistance is expected for this type of material.
Suffix-O: This suffix designates a TSR compound with good oil and/or diesel fuel resistance. Unless otherwise specified on the Engineering drawing, parts supplied will meet the oil and fuel resistance requirements specified in Tables 4-9. Typical polymers that may be used for this specification include: Acrylonitrile-butadi
Suffix-H/O: This suffix designates a heat-resistant TSR material that also exhibits good oil and diesel fuel resistance. Unless otherwise specified on the Engineering drawing, parts supplied will meet both the heat resistance and oil and fuel resistance requirements specified in Tables 4-9. Typical polymers that may be used for this specification include: Chloroprene (CR), Chlorinated Polyethylene(CPE or CM), Chloro-sulfonated Polyethylene (CSM), Epichlorohydrin copolymer (ECO), Acrylonitrile-butadi
Suffix-H/C: This suffix designates a heat- and weather-resistant TSR material with good resistance to heavy-duty diesel coolants. Unless otherwise specified on the Engineering drawing, parts supplied will meet both the heat resistance and coolant resistance requirements specified in Tables 4- 9. A typical polymer that may be used is EPDM. Minimal oil resistance is expected for this material.
Suffix-M: This suffix designates a common TSR class of materials except used in mount or isolator applications. Dynamic property requirements for these parts are generally specified separately on the Engineering drawing. Typically, the TSR material is a Natural Rubber. Natural Rubber blends with IR and SBR may be considered with prior approval. Chloroprene can be considered in a similar fashion in applications requiring high heat and oil resistance but lower flex fatigue resistance. When highly damped materials are required, butyl compounds may be specified.
Specific TSR Compound Designations
A lower case letter may be used at the end of the compound designation to specify a specific blend or composition of TSR compound. The lower case letter is added at the end, after the tensile strength number, to indicate a specific compound. For example, as indicated in Table 3, TSR65-10a designates an 8021 molding compound supplied by NRI. The specific molding compound designated by the use of the lower case letter will be indicated in Tables 4-9 or will be shown on the engineering drawing.
Explanation - Examples of Designation System
The material designation on the drawing shall consist of the TSR material prefix, followed by any suffix requirements - H, -O, -C, or -M, followed by the durometer and tensile strength specified. In some cases, a specific compound identifier (lower case letter) may be used to differentiate compound variations. A specific polymer base material may also be identified in the specification as well.
Designation on Drawings: Rubber per TMS 6039, TSR60-10
This designation identifies a basic TSR elastomer, without a specific polymer base identified, with a durometer hardness of 60 and a tensile strength of 10 MPa.
Designation on Drawings: EPDM per TMS-6039 TSR-H70-8a
This designation requires an EPDM compound meeting the heat resistance requirement with a durometer of 70 and a tensile of 8 MPa. This is also a specific compound variation as designated by the lower case letter "a." The specific material description is shown on the Engineering drawing.
Designation on Drawings: Natural Rubber per TMS-6039 TSR-M50-25b
This is an engine mount material made from Natural Rubber with a durometer of 50 and a tensile strength of 25 MPa. A specific compound, designated by the lower case letter "b", will be shown on the drawing. The print also describes specific dynamic and static spring rates for this part.
Designation on Drawings: TSR-0020 per TMS-6039
An alternate designation, intended primarily for parts still under development that may require material property modifications prior to final production release but after the print geometry has been determined.