Rocket motor components are primarily assembled by adhesion. a) For example, the RSRM (Reusable Solid Rocket Motor - part of the Space Shuttle Boosters) system contains 10,000 sq ft of bondline area. b) Rocket motors contain a variety of adhesive/substrate bond systems c) Bond system performance requirements also vary. To assemble reliable components, ATK Space Systems and customers invest substantial resources to the study of bond assembly processes. a) Surface and adhesion science; b) Adhesive chemistry; c) Process parameters; d) Contamination effects

Evans, Kurt

Mitchell, Mark

Wurth, Laura

NASA Technical Reports Server

Bond Assembly FOD Zones – A
Procedure for Assuring Acceptable
Adhesion
Kurt Evans, M&P Scientist
Laura Wurth, Design Engineer
ATK Space Systems
Brigham City, Utah
(435) 863-6130, kurt.evans@atk.com
(435) 863-3653, laura.wurth@atk.com
Mark Mitchell, FOD Focal
NASA/Marshall Space Flight Center
Huntsville, AL 35812
(256) 544-5860, mark.a.mitchell@nasa.gov
https://ntrs.nasa.gov/search.jsp?R=20090034396 2019-08-30T08:02:34+00:00Z
Rocket motor components are
primarily assembled by adhesion.
• For example, the RSRM (Reusable
Solid Rocket Motor - part of the
Space Shuttle Boosters) system
contains 10,000 ft 2 of bondline
area.
• Rocket motors contain a variety of
adhesive/substrate bond systems
• Bond system performance
requirements also vary.
To assemble reliable components,
ATK Space Systems and customers
invest substantial resources to the
study of bond assembly processes.
• Surface and adhesion science
• Adhesive chemistry
• Process parameters
• Contamination effects
0
Phenolic/Adhesive/Metal	 .
Elastomer/Metal
Elastomer/Metal
Contamination sensitivity of rocket motor
bond systems varies.
• Insensitive = no strength reduction and
usually failure remote to the contamination
interface.
• Sensitive = strength reduction and failure at
the contaminated interface.
To prevent bond system failure, operations is
vigilant about contamination control.
• Tight control is exerted on a wide range of
process contaminants; e.g., greases, oils,
tape residues, particulates, release agents,
etc.
sion and Contamination	 CATK----.,
A premier aerospace and defense compan
Effects of Silicone Contamination on the Propellant/Liner Bond System
120
100
c	 802
60
0	 0	 00	 O
n
----------------------------,----- 	 — I-- Insnsitive
	 ^—
40
Q
20
0
_ .......... _ .......... _ ...... ... _ ....... — ....... .	 -.....	 _
--------'--	
Failure mode = cohesive in propellant (remote to contamination interface).
—	 —	 —	 —	 ---
	
------- — -----------—	 -------------------------------- -- ---
0	 0	 0	 0	 0
^	 N
Silicone Contamination (milligrams of silicone/square feet of substrate area)
Effect of Silicone Contamination of Epoxy Adhesive /Metal Bond System
n 	 n 	 n25
20LM
$^^^	
---i-
•^^	 ^ 1 SensitiveI	 I	 I	 I	 I
15
-6p
:F.
	 10
CO
5
c•^^T
8
o
^.^^^	 n 	
----+-	 i	 i
0	 8:	 I
0
^^^	 9
:
:	 8Failure at contamination interface
o	 in	 in	 o	 0
C	 N	 C	 r	 no
Silicone Contamination (milligrams of silicone/square feet of substrate area)
2
The effect of incongruous forces:
• ATK adopted a zero-tolerance contamination requirement.
• ATK developed greater fidelity in contamination detection.
Extreme Requirements + Better Detection = Production Paralysis
Over zealous contamination control negatively affected production sensibility, efficiency,
and ergonomics.
Sensibility
• Tight control - indiscriminately applied to all
manufacturing areas regardless of bond system.
• “Silicone-centric” - inordinate amount of focus on
silicone contamination diverted attention away
from other release agents such as dioctyl
phthalate (DOP) or fluorocarbons.
• Upper management mandated a silicone-free
plant regardless of its ubiquity.
• “No silicone allowed” requirement applied to all
process support materials (PSM) regardless of
proximity 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 mallets
3
Efficiency
• There was a higher rate of production discrepancy
reports.
• Many plant-wide shut-downs occurred because of
detection of infinitesimal silicone amounts in PSM.
• Quality Assurance Lab was inundated with requests
to test materials for silicone content.
Ergonomics
• Effective use of functional PSM was limited or even
prohibited because of negligible silicone content.
• In some cases, opportunities for safety improvement
were missed.
4
Mix Rooms
Grit Blast Area
Floor Plan of a Manufacturing Area
ATK Operations recognized the inefficiency
of its contamination control approach and
made a prudent change.
The Bond Assembly FOD Zone (BAFODZ)
Concept
•	 Essentially, a BAFODZ is a more tightly
controlled area within a standard FOD zone.
•	 Geographically-based zone – area within the
manufacturing center
•	 Chronologically-bounded – delta time
between substrate surface preparation and
adhesive application	
o
BAFODZ
Bond
Assembly
Zone
Hardware
Assembly
nd
Cure Ovens
• Controls the flow of contaminants into the
bond assembly area.
– Control is exercised according to bond
system sensitivity.
– Control is applied during critical bond
assembly steps.
• Allows for more flexible use of PSM in other
areas of the manufacturing centers.
5
BAFODZ Implementation Protocol
Manufacturing Centers
• Continue with standard FOD mitigation
practices.
• List allowable BAFODZ PSM in the
manufacturing planning.
• Consistently educate operators on
contamination control practices.
• Control PSM changes through quality and
engineering review boards.
Quality Assurance
• Watchfully assess release agent levels in
incoming PSM.
– Outside the BAFODZ - allow for reasonable
release agent content in PSM that provide
an ergonomic advantage to manufacturing.
– Inside the BAFODZ — exercise tight control
of release agent content in PSM.
• Work with vendors to procure release-agent-free
PSM whenever practical.
Engineering and Materials & Processes (M&P)
• Reassert confidence in the contamination
cleaning effectiveness of production surface
preparation processes.
Designate if material
is FO Zone or
Bonding FO Zone
approved.
Continue with standard FOD mitigation practices.
• FOD sweeps
• Contamination control area plan
• Bonding area readiness check list
List allowable BAFODZ PSM in the manufacturing
planning.
Consistently educate operators on contamination
control practices.
Control PSM changes through quality and
engineering review boards.
Add similar Bonding FO Zone start
designations.
7
Watchfully assess release agent levels in
incoming PSM through acceptance testing and
vendor certification.
• Outside the BAFODZ - allow for reasonable
release agent content in PSM that provide an
ergonomic advantage to manufacturing.
– Note that the allowables were determined
from contamination sensitivity testing.
• Inside the BAFODZ – exercise tight control of
release agent content in PSM.
Work with vendors to procure release-agent-free
PSM whenever practical.
Success stories:
• ATK successfully negotiated a contract with 3M q
to provide silicone free Scotch Briteabrasion
pads.
• ATK successfully worked with Ansell to develop
low silicone cut—resistant gloves.
• ATK successfully worked with Westex Inc and
American Safety Clothing to eliminate the use of
silicone in the production of protective garments.
• ATK works with Elder & Jenks to manufacture
paint brushes without brads, nails and silicone
Reassert confidence in the contamination cleaning effectiveness of production surface preparation
processes.
Effect of Silicone Contamination of Epoxy Adhesive /Metal Bond Syste
I	 I	 I	 I	 ^
25
:3
	 20
15
.............
I	
°T	 g
SW = solvent wipe.
	 1
t—	 PP = present production process = solvent wipe + grit blast 	 .N
L 10
7
^
-a^	 rt	 rt	 rt	 rt	 :^
o	 :
0	 8	 N
rn 5
0
U	
•g	 •^	 6	 U
Failure at contamination interface
o	 LO	 LO	 o	 o	 a-6	 0	 0	 L6U)d
+	 +
o	 0o
A
Silicone Contamination (milligrams of silicone/square feet of substrate area)
Chronologically defines the beginning of
the BAFODZ.
• Manufacturing applies a “no touch”
practice after surface preparation.
Impressive ATK database shows that
surface preparation processes are
generally effective contamination removal
methods.
• Confirms that production surface
preparation processes remove
contamination accumulation from
upstream processing.
• If the surface preparation process is
insufficient then Engineering and M&P
must 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 protected
accordingly.
• 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 bond
assembly 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)
10


Bond Assembly FOD Zones - A Procedure for Assuring Acceptable Adhesion

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