GMNA - 9982257
Adhesive/Sealant, Room Temperature Vulcanizing, Oxime Cure for Engine Sealing Applications
|Publication Date:||1 November 2016|
Note: Nothing in this standard supercedes applicable laws and regulations.
Note: In the event of conflict between the English and domestic language, the English language shall take precedence.
Material Description. This silicone adhesive/sealant requires no catalyst or heat to cure. When applied wet (uncured) it reacts with moisture in the air (condensation cure) releasing a Methyl Ethyl Ketoxime (2-Butanone) (MEKO) by-product and fully cures to an elastomeric product, adhering to most clean surfaces without need of a primer. Adhesively bonded and fully cured adhesive/sealant acts as a barrier against oil migration across mating surfaces.
Symbols. Not applicable.
Applicability. Formed-In-Place Gasket for sealing engine covers, pans or mating of other components for oil seal integrity or to restrict dust or unwanted air and water intrusion. This product is intended for oil use only.
Application Temperature and Assembly Sequence. Unless otherwise specified by the adhesive/sealant manufacturer, apply this adhesive/sealant on the intended surface whose temperature is from 18 °C to 40 °C. Below 20 °C adhesion and cure rate slows. It is the responsibility of the applicator and the adhesive/sealant manufacturer to establish the accepted conditions, e.g., process time from applied bead to assembly to air test, temperature and adhesive/sealant cure rate to provide acceptable adhesion and leak test performance. See Assembly, Sealing and Fastening Bill of Materials (BOM) Level II for minimum process time.
Continuous Usage Temperature. Up to +175 °C as defined by SAE J2236 (see 18.104.22.168 and Table 3). Use temperature as a material strength measurement, not related to adhesion performance.
Other Surface Treatments. The adhesive/sealant approved to this standard must be applied after paint or coated part treatments (e.g., cathodic Electrodeposition Paint Operation (ELPO)/Uniprime coatings of stamped steel covers). It is the responsibility of the applicator and the adhesive/sealant manufacturer to establish the accepted conditions, e.g., time, temperature and coating cure to provide acceptable adhesion and leak test performance. Use standard test panels if available.
Cleanliness of Mating Joint Surfaces. It is the responsibility of the applicator and the adhesive/sealant manufacturer to establish and maintain the accepted surface conditions, e.g., washer cleaner concentrations, drying time, and storage protection from airborne contaminants to provide acceptable adhesion and leak test performance.
Monitoring Cleaning/Washing System Changes on Adhesion. It is the responsibility of the sealant applicator to evaluate changes in chemical cleaning/washing systems over time for parts where sealant is applied. Changes must be supported by lap shear data to evaluate the effect on sealant adhesion. Run the appropriate Table 2 test panels through the relevant washer system changes in production scale or in a pilot size operation. The values must meet or exceed Table 3 values. Any joints receiving plasma treatment as a surface preparation method in production, do not require data monitoring of a change in cleaner/washer.
Gap Limitations. Adhesive/sealant is capable of sealing a gap from 0.1 mm to 0.7 mm as measured and specified using the pressure blowout resistance test (see 22.214.171.124 and Table 1).
Remarks. The words must, shall or will as used in this document mean a mandatory requirement.
Cost. Unless otherwise specified, pricing shall be based on 20 kg (5 gal) pails compared with existing products. Material cost comparison is sealant price per mass (grams) times specific gravity. The quantity of sealant per pail varies with manufacturer. Cost comparison for decision making must be from engine specific use (grams per component, engine) and annual volumes.
Sealant unit cost increases with decreasing container size. When conducting cost studies remember that sealant cost will vary with the global region.
Based on the 2013 High Feature V6 engine usage this MEKO sealant costs $.50 cents less per engine than 9986350 non-MEKO sealant.
Process Behavior. This section compares the process behavior to competitive sealant cure systems.
Cure Rate. This silicone adhesive/sealant is slower than acetoxy adhesive/sealants but faster than alkoxy cure sealants (e.g., 9986350) from 10% to 100% Relative Humidity (RH). Depth of cure inward from an exposed edge of two aluminum square plates for seven (7) days at 20 °C is 7.1 mm.
Open Time to Joint Assembly. All Room Temperature Vulcanizing (RTV) sealant joints must be closed and clamped within eight (8) minutes of the sealant application to the mating flange. Clamped is defined as having a minimum of 80% of the fasteners tightened to the final torque with no Two (2) adjacent fasteners untightened. See 7.1.1 and 7.1.5.
Joint Performance. This adhesive/sealant lateral joint movement in millimeters (onset of cohesive or adhesive failure) on metal and plastic substrates is in Table 3. Once the lateral joint movement limit is exceeded, tensile and shear strength in megapascals is better than alkoxy cure systems (e.g., 9986350) and lower than acetoxy cure systems on all metal substrates.
Proper Use of Test Methods. Testing for this standard is based on coupon surfaces and conditions different from those of assembly or service. Standard tests permit comparison between products while attempting to represent a worse case condition related to end use. Testing actual production processes and surfaces is necessary before actions are taken. Use the test matched with the desired property/definition.
For example; Lap shear strength may be used to measure the change in bond strength due to sealant and/or process variation (e.g., ineffective surface cleanliness, build variations, etc.,) provided it mimics the actual production application with all its known variables. It shall not be used to set a single process condition such as open time because tack free time as tested and defined (See 7.1.1, 7.1.2 and 7.1.4) is the proper test and can be measured immediately on site under changing conditions.
Worst Case Test Conditions. Since bond line adhesion is the most essential sealant property, the conditions per 126.96.36.199.1 shall be considered for testing the robustness of a sealant.
• Worst finish (e.g., smooth or as cast surface finish).
• Worst contaminated surface (e.g., oily or washer residue).
• Maximum recommended gap.
• Slowest cure speed (e.g., lowest temperature and humidity for seven (7) day cure period). Seven (7) days is the industry standard for all cured test conditions.
• A joint step chamfer to maximize joint movement capabilities of the sealant.
Regulatory Restrictions. This sealant is approved for use in every global region except the European Union due to restrictions on the release of methyl ethyl ketoxime (2-butanone) during curing.
Reference Oil ASTM SF105. The current supply of ASTM SF105 will be exhausted by May 2018 as the base stock oil is no longer available. Until a suitable replacement is developed, use GMW16955, Code F oil on the next revision.