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Current Release Number Std. Revision Level

Name

Identifier

Engineering Standard Number

EngineeringStandards

IMPREGNATION,RESIN SEALANT

CORPORATE MANUFACTURING SPECIFICATION(FEATURE)

18187

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1. Scope

This specification shall be followed for resin sealant impregnation for ferrous and non-ferrousalloys including aluminum alloy, magnesium alloy, and copper alloy.

2. Applicable Documents

Applicable documents listed below may be obtained from the respective organizations listed inCES 10054.

a. MIL-STD-276 Specification, Method B

3. Definitions

There are no unique terms in this standard. Terms used in this standard that have a specificdefinition for usage in Cummins Engineering Standards are defined in CES 10056, GeneralGlossary

4. General Requirements

This procedure shall be followed in sealing porosity in ferrous and non-ferrous castings, andpowdered metal parts. Unless otherwise specified, the process conforms to MIL-STD-276

Specification, Method B.

4.1. Preparation of Castings

4.1.1. Castings should be racked in work baskets in such a manner to provide the best drainageand protection against damage. Use basket dividers between layers of castings to insure againstdamage during impregnating cycle.

4.1.2. Vapor degrease in 1.1.1. trichloroethane using simple liquid dip with slow withdrawalthru the vapor phase. Maintain solution temperature of 164-166 degrees Fahrenheit (73-74 degreesCelsius) can keep castings submerged for at least 15 minutes with temperature stabilized at thislevel.

4.1.3. Optional Method: Parts may be cleaned adequately in parts washer if water solublecoolants have been used in machining.

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4.1.4. Cleaning may need to be repeated if visual inspection determines that all oils have notbeen removed.

Parts MUST be dry and at room temperature before entering the impregnation cycle.

4.2. Impregnating Cycle

4.2.1. Refer to process flow chart in Appendix A, Figure 1, and the impregnation diagram inAppendix A, Figure 2 as guides in the operation of this impregnation process.

4.2.2. Place basket of parts in the pressure vessel and lock the cover securely. (To initiate

automatic cycle, push START button, and impregnation will be done automatically).

4.2.3. Dry Vacuum - Open vacuum pump valve, start vacuum pump and evacuate pressurevessel to not less than 29.85 of mercury. Hold for at least 10 minutes to insure removal of air fromcastings. Do not allow sealant to enter autoclave during this step.

4.2.4. Wet Vacuum - This can be programmed in if necessary and the following will be doneautomatically. With the vacuum pump running, close the vacuum valve and slowly open thetransfer valve, allowing the impregnating resin in the storage tank to be drawn into the evacuatedvessel at such a rate that high vacuum will be maintained without creating an air turbulence in theresin. When the resin has reached a level, 2-3 inches above the castings, close the transfer valve,open the vacuum valve slowly and continue to run the vacuum pump for a minimum of 5 minutesto insure removal of entrained air. A longer exposure time may be necessary depending upon thethickness of the casting.

4.2.5. Pressure Cycle - Close vacuum valve and stop vacuum pump. Apply 90-100 psi (.620-

.689 MN/M2) air pressure for 10 minutes depending upon the porosity and wall thickness of thecastings.

4.2.6. At completion of pressure cycle, close air-intake valve and reduce air pressure to

approximately 50 psi (.345 MN/M2). Open transfer valve to allow resin to return to storage tank.

As pressure drops, maintain 5-10 psi (.034-.069 MN/M2) to complete transfer to the storage tank.

Do not open the pressure vessel until air pressure has returned to zero (atmospheric).

It is advisable to release air pressure from the pressure vessel through external vent lines whichwill minimize noise and remove vapors from the vicinity.

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4.3. Cleaning

4.3.1. Remove castings from pressure vessel and allow resin to drain, particularly from holesand pockets.

4.3.2. Wash in air agitated rinse tank at ambient temperature a minimum 4-6 minutes, or untilthere is no evidence of resin on casting surfaces. A hand operated spray wash may be used to clean

blind holes and pockets, but do not exceed 25 psi (.172 MN/M2) spray pressure.

4.4. Curing Cycle - Polymerization of resin (195 - 200 degrees Fahrenheit)

4.4.1. Submerge parts in curing tank containing water with a suitable corrosion inhibitor.Maintain water temperature at 195 degrees Fahrenheit to 200 degrees Fahrenheit. Close cure tankcover. Curing cycle time is 12 to 15 minutes. Allow parts to cool to room temperature beforeremoval and testing.

4.5. Process Notes and Control Limits

4.5.1. Parts to be sealed must be dry and free of grease, oil, paint, or preservative compounds.

4.5.2. Impregnation of castings should be done after heat treating, welding, or machiningoperations.

4.5.3. Pressure test in accordance with manufacturing method applicable to individual part.

4.5.4. If part does not seal, the impregnation process may be repeated once. More than twocycles should only be performed at SQA or Product Engineerings discretion. Occasionallyadditional cycles may be warranted.

4.5.5. Specific gravity of the impregnation resin shall be maintained at limits prescribed by themanufacturer. Use Imprex 95-100A resin as make-up to maintain limits.

4.5.6. Written records shall be maintained for all temperatures, pressures, cycle times,maintenance operations, etc., which are part of this manufacturing method. Such informationshould be logged at least once each shift.

Approved Sources of Manufacturing Material

Material Vendor

95-100A Resin Imprex Milwaukee, Wis. 53227

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Appendix

Figure 1: Process Flow Chart

ResinStorage

Degrease Drying Impregnation Drain

WaterWash

CuringHot Water195 o F

200 o F

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Appendix

Figure 2: Impregnation Tank