bottle closure sealing system mark nauman andrew seagraves jeff staniszewski vincent uathavikul...
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Bottle Closure Sealing SystemBottle Closure Sealing System
Mark NaumanMark Nauman
Andrew SeagravesAndrew Seagraves
Jeff StaniszewskiJeff Staniszewski
Vincent UathavikulVincent Uathavikul
Design ReportDesign Report
BackgroundBackground
• Berry Plastics Berry Plastics - New child resistant timed-closure New child resistant timed-closure
developeddeveloped- Cap intended to seal without a linerCap intended to seal without a liner
• Dome designed to flexDome designed to flex
• Initial FEA Initial FEA - Cap showed plastic deformationCap showed plastic deformation- Inadequate for sealing as isInadequate for sealing as is
Problem DefinitionProblem Definition
• To design a liner for their existing closureTo design a liner for their existing closure
ConstraintsConstraints• Process: Compression MoldingProcess: Compression Molding• Material: Thermoplastic Elastomer (TPE)Material: Thermoplastic Elastomer (TPE)
System Level WantsSystem Level Wants• Create a seal for a liquidCreate a seal for a liquid• Maintain seal for 1 yearMaintain seal for 1 year• Minimize cost per unitMinimize cost per unit• Achieve seal within tolerance rangeAchieve seal within tolerance range
Project ScopeProject Scope
• Project WantsProject Wants• Create a waterproof sealCreate a waterproof seal
- in a leak testin a leak test- in an accelerated creep testin an accelerated creep test
• At nominal dimensionsAt nominal dimensions
• Within tolerance rangeWithin tolerance range
• Minimize cost per unit byMinimize cost per unit by- Minimizing material costsMinimizing material costs- Minimizing tooling costsMinimizing tooling costs
• Project MetricsProject Metrics• Performance in aPerformance in a
- standard leak teststandard leak test- elevated temperature leak elevated temperature leak
testtest• Nominal bottles and capsNominal bottles and caps
• Max bottle with min capMax bottle with min cap
• Min bottle with max capMin bottle with max cap
• VolumeVolume• Machining time of toolingMachining time of tooling
TerminologyTerminology
Compression MoldingCompression Molding
Initial ConceptsInitial Concepts
Constant Thickness
Variable Thickness
Cutaway Concept
Comparative Leak TestComparative Leak Test
PurposePurpose• Compares the sealing performance of Compares the sealing performance of
Constant and Variable conceptsConstant and Variable concepts
SpecificsSpecifics• 6 Different Torques6 Different Torques
- From 2 to 12 inch-poundsFrom 2 to 12 inch-pounds- 3 samples per torque level3 samples per torque level- Constant volume of water + food coloringConstant volume of water + food coloring
ResultsResults• No leaks with any sample after 48 hoursNo leaks with any sample after 48 hours
ConclusionsConclusions• Constant and Variable are equivalent in sealingConstant and Variable are equivalent in sealing
Comparative Cost StudyComparative Cost Study
At 50 million units…At 50 million units…
Cost / Unit Cost / Unit Total Cost of Total Cost of ProductionProduction
CutawayCutaway $0.0114$0.0114 $570,000$570,000
ConstantConstant $0.0126$0.0126 $630,000$630,000
VariableVariable $0.0118$0.0118 $590,000$590,000
AssumptionsAssumptions• Production: 50 Million parts/yrProduction: 50 Million parts/yr• TPE bulk cost: $2 / poundTPE bulk cost: $2 / pound• Cost of Machining Punches: Cost of Machining Punches:
$70/hr$70/hr
ResultsResults• Constant concept costs Constant concept costs
- 9.5% more than the Cutaway9.5% more than the Cutaway- 6.3% more than the Variable6.3% more than the Variable
• At 50 million parts, material At 50 million parts, material costs account for ~ 16% of the costs account for ~ 16% of the total costs and 50% of the total costs and 50% of the controllable costscontrollable costs
Cost per Unit vs. # of Units
0.0010
0.0100
0.1000
1.00E+07 1.00E+08 1.00E+09 1.00E+10
# of UnitsC
ost
Per
Un
it
Constant
Variable
Cutaway
Manufacturing ConcernsManufacturing Concerns
• Easier to seal off in Easier to seal off in the land area instead the land area instead of ridgeof ridge
• Variable and Cutaway Variable and Cutaway concepts now virtually concepts now virtually the samethe same
Cap Sleeve Punch
Ridge Liner
Concept EliminationConcept Elimination
• Constant and Variable liners have the Constant and Variable liners have the same sealing performancesame sealing performance
• Variable liner will cost less than ConstantVariable liner will cost less than Constant
• Cutaway and Variable are the same Cutaway and Variable are the same because of manufacturingbecause of manufacturing
Variable Concept willVariable Concept will
be prototypedbe prototyped
Simple ModelSimple ModelCap Liner
Bottle
Select Section View
Instron TestingInstron TestingTorque to Pressure Data
0
10
20
30
40
50
60
1 2 3 4 5 6
Torque (in-lb)
Pre
ssu
re (
psi
) Measured Values
Best Fit Line
• Linear Correlation found between Torque Linear Correlation found between Torque and Pressure can be used for FEA and and Pressure can be used for FEA and also by Berry Plasticsalso by Berry Plastics
Finite Element AnalysisFinite Element Analysis• Model of Cap, Liner and BottleModel of Cap, Liner and Bottle
• Force applied to contact areaForce applied to contact area• Boundary ConditionsBoundary Conditions - Cap sides are stationary- Cap sides are stationary - Bottle can move in y-direction- Bottle can move in y-direction
Finite Element Analysis ResultsFinite Element Analysis Results
• A cap with no liner contained stresses above yield limitA cap with no liner contained stresses above yield limit• A cap with a liner was close to yield limitA cap with a liner was close to yield limit
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
7 8 9 10 11 12 13 14
Closing Torque (in lb)
Stress (psi) -
Max SeqvMax SxMax SyFlexural Limit
Validation of Test DesignValidation of Test Design• O-ring and compression liners compared O-ring and compression liners compared
with FEAwith FEA
• O-ring liner performs similar to actual O-ring liner performs similar to actual design under same loaddesign under same load- Within 8% on all stressesWithin 8% on all stresses- Within 2% on all deflectionsWithin 2% on all deflections
• O-ring is an accurate O-ring is an accurate approximation geometryapproximation geometry
Standard Leak TestStandard Leak TestProcedureProcedure• Bottles are sealed to predetermined range of torqueBottles are sealed to predetermined range of torque• Opening torque immediately applied and measuredOpening torque immediately applied and measured• Bottles are resealed and checked for leaking over 2 Bottles are resealed and checked for leaking over 2
week timeweek time• Opening torque is applied and measuredOpening torque is applied and measured
ResultsResults• No bottles leak in this timeNo bottles leak in this time• Opening torque slightly lower Opening torque slightly lower
after 2 weeksafter 2 weeks
Douter = 1.42”Dinner = 1.06”Thickness = .04”
Elevated Temperature TestElevated Temperature Test
• Used to simulate relaxation over timeUsed to simulate relaxation over time• Sealed bottles are put in environmental chamberSealed bottles are put in environmental chamber
- 2 weeks at 100 2 weeks at 100 °F ~ 2 months°F ~ 2 months
• All bottles remained sealed over periodAll bottles remained sealed over period• Relaxation curve made using existing dataRelaxation curve made using existing data
- Immediate opening torqueImmediate opening torque- Opening torque after 2 weeksOpening torque after 2 weeks- Opening torque after simulated 2 monthsOpening torque after simulated 2 months- Match shape of current relaxation curvesMatch shape of current relaxation curves
Elevated Temperature Test ResultsElevated Temperature Test Results
• 10 in lb may be 10 in lb may be inadequate to sealinadequate to seal- Cap relaxes too Cap relaxes too
much over the periodmuch over the period
• Higher than 12 in lb Higher than 12 in lb will seal over timewill seal over time- Curves flatten outCurves flatten out
ConclusionsConclusions• Testing ShowsTesting Shows
- Prototype maintains short term waterproof sealPrototype maintains short term waterproof seal• Performance Metric of Standard Leak test satisfiedPerformance Metric of Standard Leak test satisfied
- Waterproof seal intact after simulated 2 monthsWaterproof seal intact after simulated 2 months• Performance Metric of Elevated Temperature test satisfiedPerformance Metric of Elevated Temperature test satisfied
• FEA ShowsFEA Shows- Prototype design and actual design behave similarPrototype design and actual design behave similar- Higher torques could cause plastic deformationHigher torques could cause plastic deformation
• Analysis ShowsAnalysis Shows- Seal would survive simulated yearSeal would survive simulated year
• PrototypePrototype- Simulates the actual liner design to be implemented by BerrySimulates the actual liner design to be implemented by Berry
Implementation PlanImplementation Plan
• Test the cap for relaxation over a Test the cap for relaxation over a simulated yearsimulated year
• Optimize liner thickness to Optimize liner thickness to reduce production costsreduce production costs
• Small scale production of punch Small scale production of punch for further physical and for further physical and consumer testingconsumer testing
• Large scale production of punch Large scale production of punch for commercial use of cap and for commercial use of cap and linerliner
QuestionsQuestions
• Elevated Temperature
• FEA Stress
• Manufacturing
• Simple Model
• Instron Setup
• Tolerance Variation