Bond Assembly FOD Zones – AProcedure for Assuring AcceptableAdhesion

Kurt Evans, M&P ScientistLaura Wurth, Design EngineerATK Space SystemsBrigham City, Utah(435) 863-6130, kurt.evans@atk.com(435) 863-3653, laura.wurth@atk.com

Mark Mitchell, FOD FocalNASA/Marshall Space Flight CenterHuntsville, AL 35812(256) 544-5860, mark.a.mitchell@nasa.gov

https://ntrs.nasa.gov/search.jsp?R=20090034396 2020-04-04T22:54:49+00:00Z

Rocket motor components areprimarily assembled by adhesion.

• For example, the RSRM (ReusableSolid Rocket Motor - part of theSpace Shuttle Boosters) systemcontains 10,000 ft 2 of bondlinearea.

• Rocket motors contain a variety ofadhesive/substrate bond systems

• Bond system performancerequirements also vary.

To assemble reliable components,ATK Space Systems and customersinvest substantial resources to thestudy of bond assembly processes.

• Surface and adhesion science

• Adhesive chemistry

• Process parameters

• Contamination effects

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Elastomer/Metal

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Contamination sensitivity of rocket motorbond systems varies.

• Insensitive = no strength reduction andusually failure remote to the contaminationinterface.

• Sensitive = strength reduction and failure atthe contaminated interface.

To prevent bond system failure, operations isvigilant about contamination control.

• Tight control is exerted on a wide range ofprocess contaminants; e.g., greases, oils,tape residues, particulates, release agents,etc.

sion and Contamination CATK----.,

A premier aerospace and defense compan

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The effect of incongruous forces:• ATK adopted a zero-tolerance contamination requirement.• ATK developed greater fidelity in contamination detection.

Extreme Requirements + Better Detection = Production ParalysisOver zealous contamination control negatively affected production sensibility, efficiency,and ergonomics.

Sensibility

• Tight control - indiscriminately applied to allmanufacturing areas regardless of bond system.

• “Silicone-centric” - inordinate amount of focus onsilicone contamination diverted attention awayfrom other release agents such as dioctylphthalate (DOP) or fluorocarbons.

• Upper management mandated a silicone-freeplant regardless of its ubiquity.

• “No silicone allowed” requirement applied to allprocess support materials (PSM) regardless ofproximity to bond assembly processes.

• Unusual requests to test PSM for silicone content.

Silicone content testing atrocities

• Grease

• 3-in-1 oil

• Shoelaces

• Toothbrushes

• Ratchet tie-down

• Magnetic signs

• Cut back tool

• Bug sprayers

• Mold release

• Mouse pads

• Rubber mallets3

Efficiency

• There was a higher rate of production discrepancyreports.

• Many plant-wide shut-downs occurred because ofdetection of infinitesimal silicone amounts in PSM.

• Quality Assurance Lab was inundated with requeststo test materials for silicone content.

Ergonomics

• Effective use of functional PSM was limited or evenprohibited because of negligible silicone content.

• In some cases, opportunities for safety improvementwere missed.

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Mix Rooms

Grit Blast Area

Floor Plan of a Manufacturing Area

ATK Operations recognized the inefficiencyof its contamination control approach andmade a prudent change.

The Bond Assembly FOD Zone (BAFODZ)Concept

• Essentially, a BAFODZ is a more tightlycontrolled area within a standard FOD zone.

• Geographically-based zone – area within themanufacturing center

• Chronologically-bounded – delta timebetween substrate surface preparation andadhesive application

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• Controls the flow of contaminants into thebond assembly area.

– Control is exercised according to bondsystem sensitivity.

– Control is applied during critical bondassembly steps.

• Allows for more flexible use of PSM in otherareas of the manufacturing centers.

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BAFODZ Implementation Protocol

Manufacturing Centers

• Continue with standard FOD mitigationpractices.

• List allowable BAFODZ PSM in themanufacturing planning.

• Consistently educate operators oncontamination control practices.

• Control PSM changes through quality andengineering review boards.

Quality Assurance

• Watchfully assess release agent levels inincoming PSM.

– Outside the BAFODZ - allow for reasonablerelease agent content in PSM that providean ergonomic advantage to manufacturing.

– Inside the BAFODZ — exercise tight controlof release agent content in PSM.

• Work with vendors to procure release-agent-freePSM whenever practical.

Engineering and Materials & Processes (M&P)

• Reassert confidence in the contaminationcleaning effectiveness of production surfacepreparation processes.

Designate if materialis FO Zone orBonding FO Zoneapproved.

Continue with standard FOD mitigation practices.• FOD sweeps• Contamination control area plan• Bonding area readiness check list

List allowable BAFODZ PSM in the manufacturingplanning.Consistently educate operators on contaminationcontrol practices.Control PSM changes through quality andengineering review boards.

Add similar Bonding FO Zone startdesignations.

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Watchfully assess release agent levels inincoming PSM through acceptance testing andvendor certification.

• Outside the BAFODZ - allow for reasonablerelease agent content in PSM that provide anergonomic advantage to manufacturing.

– Note that the allowables were determinedfrom contamination sensitivity testing.

• Inside the BAFODZ – exercise tight control ofrelease agent content in PSM.

Work with vendors to procure release-agent-freePSM whenever practical.

Success stories:

• ATK successfully negotiated a contract with 3M qto provide silicone free Scotch Briteabrasionpads.

• ATK successfully worked with Ansell to developlow silicone cut—resistant gloves.

• ATK successfully worked with Westex Inc andAmerican Safety Clothing to eliminate the use ofsilicone in the production of protective garments.

• ATK works with Elder & Jenks to manufacturepaint brushes without brads, nails and silicone

Reassert confidence in the contamination cleaning effectiveness of production surface preparationprocesses.

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Chronologically defines the beginning ofthe BAFODZ.

• Manufacturing applies a “no touch”practice after surface preparation.

Impressive ATK database shows thatsurface preparation processes aregenerally effective contamination removalmethods.

• Confirms that production surfacepreparation processes removecontamination accumulation fromupstream processing.

• If the surface preparation process isinsufficient then Engineering and M&Pmust develop more effective method.

Improved approach of manufacturing to contamination is more sensible.

• Recognize the reality that release agent contamination is pervasive because of its functionality.

• Some bond systems are sensitive to many contaminants and the substrates must be protectedaccordingly.

• Other bond systems are insensitive and do not require the same degree of protection.

• The risks of contamination can be managed in a more proactive manner.

– Trust the surface preparation process.

– Do not contact the hardware after surface preparation.

– Do not apply tight contamination content standards to PSM that are not used in a critical bondassembly area (BAFODZ).

– Focus vendor attention on release-agent-free PSM for items where it is warranted by sensitivity.

Acknowledgements

• The following ATK Space Systems personnel contributed significant information to this presentation:

– Mike Killpack (Manager Analytical Chemistry)

– Craig King (Contamination Control Engineering Lead)

– Kelly Field (Procurement Quality Engineer)

– Becky Brown (Process Engineer Huntsville Space Operations)

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