1、 WORLDWIDE ENGINEERING STANDARDS Material Specification GMW15822 Fluorocarbon Coating for Electrodeposition Masking Copyright 2012 General Motors Company All Rights Reserved September 2012 Originating Department: North American Engineering Standards Page 1 of 4 1 Scope This specification covers the
2、basic requirements for a fastener coating to prevent buildup of electrodeposited primers (E-coat). 1.1 Material Description. This coating is a fluoropolymer-based coating specially applied to the threads and other locations on a fastener (mostly on threads of nuts and studs). The coating prevents E-
3、coat from adhering to the protected areas. 1.2 Symbols. Not applicable. 1.3 Typical Applications. Weld studs and nuts; clinch (pierce) nuts and studs; tapping plates. 1.4 Remarks. Use of this finish on threaded surfaces and/or bearing surfaces of joints could affect the torque-tension relationship.
4、It is recommended that a torque-tension study of the fastener joint be performed before releasing this finish on a new application. 2 References Note: Only the latest approved standards are applicable unless otherwise specified. 2.1 External Standards/Specifications. ISO 16047 2.2 GM Standards/Speci
5、fications. GMW3059 2.3 Additional References. TMC003 Material Safety Data Sheet guidance documents (available at ). Approved Finishers List (available at ). 3 Requirements 3.1 Appearance and Cure. The coating shall have a uniform appearance and be free of tears, runs, and flaked areas. It shall have
6、 an identifiable color. Red color is not permissible. 3.1.1 The cure parameters for the specific coating shall be determined using the appropriate time/temperature relationship as recommended by the coating chemical manufacturer to achieve the performance as listed in this standard. In no case shall
7、 the cure cycle affect the mechanical or dimensional properties of the parts being coated. 3.1.2 The properly cured coating shall prevent adhesion of electrodeposition primers and meet the drive torque values specified in Tables 1 thru 3. 3.1.3 The cured coating shall be sufficiently damage resistan
8、t to prevent chipping or other coating removal during normal handling and shipping of parts. The coating shall be compatible with plant paint systems. 3.1.4 Plain parts shall be received with a light rust-preventive coating to prevent flash rusting of parts during processing, shipping and short-term
9、 plant storage. 3.2 Coating Coverage and Thickness. 3.2.1 The coating shall be applied to the contact surfaces of the internal thread areas of nuts and tapping plates and to the external thread areas of bolts and studs subject to specification restrictions. 3.2.2 Unless otherwise noted on the part d
10、rawing, coating locations and coverage shall meet the following restrictions: 3.2.2.1 The coating on externally threaded parts shall extend to the thread run-out for shanked products and to within three (3) thread pitches of the head to shank junction on full-threaded parts. However, in no case shal
11、l the coating extend below a plane parallel to the weld nibs. No coating may be present on the head, including the underhead bearing surfaces of the bolts and studs, the nut hex flats and bearing surfaces, and on the weld projection nibs, flats and any of the head surfaces of weld studs and nuts. 3.
12、2.2.2 The coating shall not be so thick as to interfere with the free insertion of a mating fastener. Free-drive torque is the amount of torque necessary to drive a specified mating fastener through the coated part. The maximum free-drive torque is as listed in Tables 1 thru 3. 3.3 Coefficient of Fr
13、iction/Free-drive Torque. 3.3.1 After coating, parts shall meet the free-drive torque and torque-tension requirements for their Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,
14、-GM WORLDWIDE ENGINEERING STANDARDS GMW15822 Copyright 2012 General Motors Company All Rights Reserved September 2012 Page 2 of 4 respective sizes and types (Tables 1 thru 3). The torque-tension values shall be measured per ISO 16047. 3.3.2 The coefficient of friction of the threads, as measured per
15、 ISO 16047 shall also be measured and controlled to within a 0.06 range during the production life of the part. 3.3.3 For the Production Part Approval Process (PPAP), perform the following tests and include in the PPAP submission: Measure free-drive torque on ten (10) random parts. Measure torque te
16、nsion and coefficient of the thread per ISO 16047 on thirty (30) random parts. 3.3.4 For new chemical approval, coat studs, weld nuts, and clinch (pierce) nuts of various sizes, covering the smallest and largest sizes listed in Tables 1 thru 3. Test coated parts per ISO 16047 with at least thirty (3
17、0) parts per size and type. Each measured free-drive torque value must be at or below the respective maximum free-drive torques in Tables thru 3. The 3 values for torque tension must fall within the limits in Tables1 thru 3. The 3 range for each group of thread coefficient of friction test results m
18、ust be within 0.06. 3.4 E-coat Resistance. For new chemical and applicator approval, coat the threads of various studs and nuts, covering the largest and smallest sizes in Tables1 thru 3. The sample size for each size/type shall be ten (10). The coating must be processed in a regular production line
19、, using normal production coating material, controls and handling. After sufficient curing (24 hours maximum), apply E-coat to the parts and examine for E-coat adhesion to the fluorocarbon coating. Submit all parts to GM for examination. Table 1: Studs Basic Size Free-drive Torque (Nm) Maximum Torqu
20、e (Nm) Tension (kN) Millimeters: M6 x 1 M8 x 1.25 M10 x 1.5 M12 x 1.75 1 1 2 2.5 8 20 33 60 5.5 to 12 13 to 24 15 to 35 22 to 40 Inches: 1/4 to 20 5/16 to 18 3/8 to 16 7/16 to 14 1/2 to 13 1 1 2 2 2 5 9 15 25 40 4 to 10.5 6 to 15 8 to 18 12 to 23 14 to 27 Table 2: Weld Nuts Basic Size Free-drive Tor
21、que (Nm) Maximum Torque (Nm) Tension (kN) Millimeters: M5 x 0.8 M6 x 1 M8 x 1.25 M10 x 1.5 M12 x 1.75 M14 x 2 M16 x 2 1 1 1 2 2 2 2.5 8 12 21 40 66 100 155 4 to 10.5 6 to 15 12 to 22 16 to 36 25 to 45 35 to 55 55 to 75 Inches: 1/4 to 20 5/16 to 18 3/8 to 16 7/16 to 14 1/2 to 13 1 1 2 2 2 10 20 35 45
22、 65 5 to 18 11 to 30 15 to 40 18 to 43 20 to 49 Table 3: Clinch (Pierce) Nuts Basic Size Free-drive Torque (Nm) Maximum Torque (Nm) Tension (kN) Millimeters: M5 x 0.8 M6 x 1 M8 x 1.25 M10 x 1.5 M12 x 1.75 1 1 1 2 2 8 9 20 35 65 4.5 to 11 6 to 12 12 to 26 18 to 36 27 to 45 Inches: 1/4 to 20 5/16 to 1
23、8 3/8 to 16 1 1 2 10 20 35 6 to 15 12 to 28 14 to 35 Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW15822 Copyright 2012 General Motors
24、Company All Rights Reserved September 2012 Page 3 of 4 4 Manufacturing Process The GM approved process, including pre-treatment (cleaning), coating and post-treatment, shall be performed by one company in one facility. The equipment, process controls, chemicals and location used must remain the same
25、 for regular production. This includes pre-treatment (such as cleaning) and post-treatment. These operations cannot deviate without prior approval by GM. For PPAP and each production lot of coated parts, the applicator shall supply a certificate to the customer with the following information: This s
26、pecification number. Applicator name and address. Coating system and color used. Part number. Date(s) the parts were coated. Coefficient of friction of coating at PPAP. The applicator shall keep the certificates for a minimum of five (5) years. 5 Rules and Regulations 5.1 Legal Regulations. All mate
27、rials must satisfy applicable laws, rules, regulations and recommendations valid in the country of usage. 5.2 Language. In the event of conflict between the English and domestic language, the English language shall take precedence. 5.3 Inspection and Rejection. Samples of components or materials rel
28、eased to a GM material specification shall be tested for conformity with the requirements of this material specification and approved by the responsible Engineering department prior to commencement of delivery of bulk supplies. A new approval must be received for any changes, e.g., properties, manuf
29、acturing process, location of manufacture, etc. If not otherwise agreed, all testing and documentation normally required for initial release must be completed. It is the responsibility of the supplier to inform the customer in a timely manner, without solicitation, and to include documentation of al
30、l modifications of materials and/or processes and to apply for a new release. If not otherwise agreed, all release tests shall be repeated and documented by the supplier prior to commencement of delivery of non-conforming bulk supplies. In individual cases, a shorter test can be agreed to between th
31、e responsible Engineering department and the supplier. 5.4 Material Safety Data Sheets/Safety Data Sheets (MSDS/SDS). For new product submissions, or when a change in chemical composition of an existing product has occurred, a complete copy of the Material Safety Data Sheet/Safety Data Sheet must be
32、 submitted in compliance with the Globally Harmonized System of Classification and Labeling of Chemicals (GHS) requirements or other country-specific MSDS/SDS requirements. In addition, product MSDS/SDS submissions must be in compliance with specific country General Motors TMC003 Material Safety Dat
33、a Sheet/Safety Data Sheet guidance documents where available. 5.5 All materials supplied to this standard must comply with the requirements of GMW3059, Restricted and Reportable Substances for Parts. 6 Approved Sources Materials supplied to this specification must be approved by General Motors. A li
34、st of approved materials can be found in the GM Approved Finishers List. This GM Material File is provided to third parties to reduce redundant testing of materials. If approved material already listed is used, the part supplier can use GM Material File reference for Production Part Approval Process
35、 (PPAP) material approval. If the decision is made to use a not yet approved material, contact the responsible GM Materials Engineer for detail on the approval process. The material approval process must be completed prior to PPAP start date of the part supplied to General Motors. 7 Notes 7.1 Glossa
36、ry. Free-drive Torque: Amount of torque necessary to drive a specified mating fastener through the coated part. 7.2 Acronyms, Abbreviations, and Symbols. Sigma GHS Globally Harmonized System of Classification and Labeling of Chemicals GSSLT Global Subsystem Leadership Team MSDS Material Safety Data
37、Sheet PPAP Production Part Approval Process SDS Safety Data Sheet Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-GM WORLDWIDE ENGINEERING STANDARDS GMW15822 Copyright 2012 Ge
38、neral Motors Company All Rights Reserved September 2012 Page 4 of 4 8 Coding System This standard shall be referenced in other documents, drawings, etc., as follows: Coat part at specified areas per GMW15822 9 Release and Revisions This standard was originated in March 2008. It was first approved by
39、 the GMW Finish Team in August 2010. It was first published in August 2010. Issue Publication Date Description (Organization) 1 AUG 2010 Initial publication. 2 SEP 2012 Removed type A and B designations, removed 3.5 (weld splatter test), 3.6 (coating removal test), 3.2.3. Revised 3.1.4, 3.3. Added 3.4 (E-coat resistance). Other editorial changes. (Finishes & Coatings GSSLT) Copyright General Motors Company Provided by IHS under license with General Motors CompanyNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
