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FIPG

Posted on 5/13/2013 1:15:45 PM By Sandy Niks
  

Formed-in-place gaskets (FIPG) have been in use for a few decades in the automotive industry. Many applications are in the power train system – engine and driveline. This would include engine block to oil pan, engine cover to engine block, intake manifolds, thermostat housings, pump covers, power steering housings, etc. Additional applications are in components, particularly electrical components and lamps, such as headlamps, side markers, etc.

The advantages of using an FIPG instead of a die cut gasket include reduction of waste – all of the pieces that would need to be cut from the sheet of gasket material to fit the pattern of the parts being assembled could easily be greater than what is actually used. An adhesive is often preapplied to the gasket to maintain its position in the joint until assembled, requiring a release paper to be applied to protect the adhesive prior to assembly, then removed and discarded, producing more waste. For variations in the design of the mating surfaces of the parts being designed, different gaskets would need to be produced – increasing part numbers and inventory to be managed. Assuming bond gaps or operating conditions did not change significantly, the same adhesive would be used with just a change in the application pattern. That is not to say there are not expenses with FIPG. Many adhesive materials cost more than gasket materials; dispensing equipment is needed, usually robotically controlled; and there is still some waste when the adhesive/sealer is purged periodically at whatever schedule is necessary to protect the equipment.

The FIPG works as an adhesive/sealer to prevent fluid leakage as well as dust or air intrusion, just as a gasket would. The pressures involved in these applications generally require more adhesive strength than the typical sealant. In addition, applications in the power train system are routinely exposed to higher temperatures. There are room temperature vulcanizing (RTV) silicones that meet the requirements. Early formulations of RTV silicones produced acetic acid as a by-product of the curing reaction. For bare metal (or even primed and painted metal) substrates, coupled with a joint design that could trap the acetic acid in or near the bond area, this would cause a corrosion problem. The RTV silicones were reformulated to eliminate the production of acetic acid, thus eliminating the corrosion issue and making the RTV silicones a viable candidate for production. There are several additional adhesive chemistry options for other applications where temperatures and fluid exposures aren’t as severe.

Testing FIPG materials includes many of the usual material tests – color, viscosity, working life, specific gravity, hardness, etc. Additional tests may include blowout resistance, heat aging, and fluid resistance. Lap shear test specimens and bulk tensile test specimens are typically used to evaluate any degradation due to the environmental cycling.

Some standards relevant to FIPG materials:

ASTM D6411, “Standard Specification For Silicone Rubber Room Temperature Vulcanizing Low Outgassing Materials “ [ASTM D14, Adhesives, jurisdiction]

ASTM F2468, “Standard Classification for Specifying Silicone Adhesives and Sealants for Transportation Applications“ [ASTM F03, Gaskets, jurisdiction]

SAE J1497 (cancelled), “Design Guide for Formed-in-Place Gaskets” [SAE Ic Powertrain Steering Committee jurisdiction]

FIPG videos:

FIPG Sealant Application System, emphasizing the equipment.

3M HDD FIPG Sealing

Formed (or Foamed)-in-place gasket presentation by Rovski

Dispensing liquid gasket example.  Note that it includes the purging cycle.

Dymax Form In Place / Cure In Place Gaskets being Dispensed by Precisions Valve & Automation, Inc.'s Dispensing Machine.

FIPG Suppliers: Reminder - this is not an endorsement of any company. Nor, I am sure, is this a complete list of suppliers.

3M; Example 3M product

ACC Silicones Europe

Dow Automotive

ITW Devcon

Hernon Mfg., Inc.

Loctite™, Henkel

Rovski  

References:

Handbook of Adhesive Bonding, edited by Charles V. Cagle, McGraw-Hill Book Company, 1973, ISBN:  0-07-009588-4, Chapter 22, “Adhesives in the Automobile Industry”, by Sumner B. Twiss.

Handbook of Adhesive Technology, edited by A. Pizzi, K. L. Mittal, Marcel Dekker, Inc., 1994, ISBN:  0-8247-8947-1, Chapter 40, “Adhesives in the Automotive Industry”, by Eckhard H. Cordes.

Engineered Materials Handbook®, Volume 3, Adhesives and Sealants, Hal F. Brinson, Technical Chairman ASM International Handbook Committee, ASM International, 1990, ISBN: 0-87170-281-9, pp 215-222, “Silicones”, by M. Dale Beers, Jerome M. Klosowski; pp 551-557, “Automotive Applications for Adhesives”,  by Kieran Drain and Sarat Chandrasekharan; pp 604-612, “Applications for Sealants”, by Kent Adams.



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