Checkweigher Design Concept

1
Checkweigher Design Concept

• All-Fill Inc.
• Dan MacGuigan, Matt Griffith,
• Phil Mitchell, Richard Maurer

2
Introduction of Project

• Weighs Products
• Quality Control

• Rejects out-of-spec Products
• Up to 200 products/min.

3
Improvement Objectives (Wants)

• Decrease Cost
• Material
• Manufacturing/Machining Time
• Assembly Time
• Fewer Parts
• Fewer Required Tools
• Increase Marketability
• Easier Maintenance
• Tool-less Belt Changes
• Drive Belt
• Conveyor Belt
• Faster Order Turnaround

4
Design Constraints

• Safety
• Protection From Moving Parts
• Design Against Catastrophic Failure
• Weight
• Cannot Increase Overall Weight
• Footprint
• Cannot Change Current Footprint
• Life
• Service Life Cannot Decrease

5
Improvement Metrics
Metric Current Target Achieved
Material Cost 290/740 230/590 220/184
Manufacturing Time 18.5 hrs 14 hrs 10 hrs
Assembly Time 17 min 14 min 14 min
Number of Parts 86/208 75/100 80/99
of Rollers 1 2 2
of Tools Required for Belt Change 3 0 0
6
How to Meet Wants

• Divide Checkweigher into Subsystems
• Each Subsystem Offers Benefits
• Some Subsystems Interrelated
• Compounded Improvements

7
Identification of Subsystems

• Motor Mount
• Roller Attachment
• Knife-Edge
• Sidebars Tie Bars

Current Design
8
Motor Mount

• Wants
• Lower Cost (Benefits Sponsor)
• Fewer Small Parts (Nuts, Washers, etc.)
• Less Costly Manufacturing
• Faster Assembly
• Increase Marketability (Benefits Customer)
• Easy Tensioning of Timing Belt
• Tool-less / Fast Belt Change

Metric Current Target Achieved
Time to Change Belt 7.3 min 5 min 3.3 min
Time to Properly Tension belt 2 min 1 min 0.5 min
of Tools to Change Belt 3 0 0
Number of Parts 6 5 4
9
Motor Mount - Current
10
Motor Mount - New
Thumb Screw
11
Roller Integration

• Wants
• Lower Cost (Benefits Sponsor)
• Lower Manufacturing Cost
• Increased Marketability (Benefits Customer)
• Tool-less Belt Change
• More Versatile

Metric Current Target Achieved
Time to Assemble 17 min 13 min 14 min
of Rollers Types 1 2 2
of Tools to Change Belt 3 0 0
Manufacturing Cost 1110 840 600
12
Roller Integration Current
Roller Attachment Points
Current Attachment Points of Rollers
13
Roller Integration NewEnd Caps
Drive End Cap
Knife-Edge End Cap
Conventional Idler End Cap
14
End Cap Integration
Snap Ring and Pliers
Concept Roller Attachment Points
Cotter Pin
15
Knife-Edge

• Wants
• Lower Cost (Benefits Sponsor)
• Lower Cost
• Simpler
• Increased Marketability (Benefits Customer)
• Less Vibration
• Less Belt Wear
• Shorter Transition Distance

Metric Current Target Achieved
Time to Manufacture 7 hr 5 hr 3.7 hr
Material Cost 740 590 184
of Parts 208 100 99
16
Knife-Edge - Current
Nylon Spacer
Bearing

• Problems
• Many Small Parts
• Expensive
• Difficult to Assemble

17
Knife-Edge - New

• Material PTFE (Teflon)
• Low Coefficient of Friction
• High Melting Temperature
• Inexpensive
• Few Parts

18
Sidebars Tie Bars

• Wants
• Lower Cost (Benefits Sponsor)
• Lower Material Cost
• Shorter Manufacturing Time
• End Cap Integration
• Increased Marketability (Benefits Customer)
• FDA Approved
• Lighter

Metric Current Target Achieved
Material Cost (per pair) 20 10 6
Mass/Length 0.05 lbm/in 0.03 lbm/in 0.03 lbm/in
FDA Approved Yes Yes Available
19
Sidebars - New

• Polycarbonate
• Lighter
• Less Expensive
• Easily Machined
• Sufficient Mechanical Properties
• FDA Approved Available
• End Cap Integration

20
Tie Bars - New

• Redesigned for Compatibility with Polycarbonate
  Sidebars
• Single Attachment to Sidebar
• Material Change
• From Aluminum to Polycarbonate
• Less Costly
• Lighter

21
Assembled Prototype
22
Testing

• Weight
• Assembly Time
• Maintenance Time
• Drive Belt Change
• Conveyor Belt Change
• Accuracy Precision
• Product Weight Measurements

23
Weight

• Current Weight
• 7lbs 4 ounces
• New Weight
• 6lbs 3ounces
• 17.4 Weight Reduction

Current
Prototype
24
Assembly Time
Current
Prototype

• Current Assembly
• 17 Minutes
• 4 Tools Needed
• New Assembly
• 14 minutes
• 2 Tools Needed

18 Reduction In Assembly Time
25
Maintenance Time

• Conveyor Belt Change Time Increased
• Due to Sidebar Material Change
• Introduce Helicoils in Next Prototype
• Drive Belt Change Time Decreased
• Old Time 730
• New Time 330
• 47 Decrease in Time Required
• Tool-less
• Less Hardware Required

26
Accuracy and Precision Testing

• Sample Products Run on Actual Machine
• Three Different Products
• Representative of a Range of Weights
• Three Conveyor Units Tested
• Old Design
• Conventional Prototype
• Knife-Edge Prototype

27
Accuracy Results

• Offline Mass Compared to Data From
• Old Design
• Prototype of New Design
• Prototype of New Design with Knife-edge

28
Precision Results

• At Least 1 New Design Outperformed Current
  Checkweigher in Every Test

29
Overall Benefits

• Tool-less Belt Change
• Motor Mount
• Cotter Pin
• Lighter
• Sidebars
• Tie Bars
• Fewer Parts
• Knife-Edge
• Motor Mount

• Versatile
• End Caps
• Knife-Edge
• Sidebars
• Less Expensive

Component Money Saved
Motor Mount 11
Knife-Edge 480
Sidebar (2) 14
Tie Bar (3) 21
Manufacturing Time 510
TOTAL SAVED 1036
(60 of Current Checkweigher Cost) (33 of
Retail)
30
Conclusion

• Design
• Lighter
• More Versatile
• Easier Maintenance
• Less Expensive
• Prototyping
• Fully Functional Prototype
• 100 Scale
• Testing
• 18 Assembly Time Reduction
• Tool-Less Belt Changes
• More Accurate
• More Precise

31
Implementation Plan

• Provide to All-Fill
• Bill of Materials
• Complete Electronic Drawing Package
• Checkweigher Prototypes
• Manufacture Three Complete Improved Checkweigher
  Designs
• Run Mock Production Line

32

• Questions
• Acknowledgements
• Nate Cloud
• Ha Dinh
• Ed White
• Dave Kendell
• Steve Beard

33
BoM - Conventional
Quantity Hardware
6 1/4-20x1/2" Hex Socket Bolt
9 5-40x1/4" Flat Head Screw
2 1/4-20x1" Hex Socket Bolt
2 1/4-20 Washer
2 1/4-20 Lock Washer
4 1/4-20 Thumb Wheel
2 10-32x1" Hex Bolt
4 10-32 Washer
4 10-32 Lock Washer
2 10-32x1" Wing Bolt
2 10-32 Thumb Wheel
4 10-32x1/2" Hex Socket Bolt
4 Brass Washer (ID 3/8", OD .75")
4 Hairpin Cotter Pin (Wire Diameter 0.1")
8 1/8"x1" Steel Dowel
Conventional Roller Conventional Roller Conventional Roller
Quantity Part Drawing Number
1 Motor with Sprocket N/A
1 Motor Plate MM1
2 Spacer MM2
1 Motor Mount MM3
3 Tie Bar S1
2 Sidebar S2
2 Drive End Cap EC1
2 Idler End Cap EC2
1 Idler Roller with Bearings N/A
1 Drive Roller with Bearings and Sprocket N/A
2 Roller Shaft S3
1 Table Top S4
1 Drive Belt N/A
1 Conveyor Belt N/A
     
34
Sidebar
35
Right End Cap (Knife-Edge)
36
Left End Cap (Knife-Edge)
37
Lateral Support
38
Knife-Edge Support
39
End Cap Drive
40
End Cap - Idler
41
Motor Mount
42
Motor Plate
43
Spacers
44
Tie Bars
45
Table Top
46
Roller Shaft
47
Sidebar Deflection Analysis

• Assumptions
• Height 1.15
• Length (support to support) 4.5
• Width (plastics) .5
• Width (Aluminum) .5
• Package weight 12 Lb.
• Elastic Moduli
• Aluminum - 57,000 ksi
• UHMW PE - 100 ksi
• Nylon 66 200 ksi
• Polycarbonate 392 ksi

48
SchematicSidebar side view
Package weight
Support from below checkweigher
Support from below checkweigher
49
Sidebar Deflection Analysis

• Iplastic .063 in4
• IAluminum .048 in4
• Max deflection at center of sidebar
• Aluminum - .0000084
• UHMW PE - .0036
• Nylon 66 - .0018
• Polycarbonate - .00092

Worst Case Scenario
50
Sidebar Deflection AnalysisStandard loading

• Assume 2 equally loaded sidebars
• Deflections
• UHMW PE .0018
• Nylon 66 .0009
• Polycarbonate .00046
• Aluminum .0000042
• Machining precision is .0005, greater than
  potential deflection of Polycarbonate.

51
Raw Data Tube (Slow Speed)
52
Raw Data Tube (Fast Speed)
53
Raw Data Box (Slow Speed)
54
Raw Data Canister (Slow Speed)
55
Raw Data Canister (Fast Speed)
56
Suggested Improvements

• Introduce helicoils for easier threading
• Hole in Motor Mount to allow access to screw
  covered by Motor Mount
• Screws through Knife-edge end caps into
  knife-edge lateral support
• Consider replacing more aluminum parts with
  polymer

57
Material Cost
Material Vendor Height (in.) Width (in.) FDA-Approved? Cost per ft.
Aluminum (anodized) McMaster-Carr 1.5 0.375 no 9.07
Aluminum (non-anodized) McMaster-Carr 1.25 0.375 no 4.35
Aluminum (non-anodized) Metals Depot (MetalsDepot.com) 1.25 0.375 no 2.75
Polycarbonate McMaster-Carr 1.5 0.5 no 3.23
Polycarbonate San Diego Plastics (www.sdplastics.com) 1.5 0.5 yes 3.00
UHMW Polyethylene McMaster-Carr 1.5 0.5 yes 3.16
UHMW Polyethylene Modern Plastics (www.modernplastics.com) 1.5 0.5 yes 2.50
Nylon 66 McMaster-Carr 1.5 0.5 yes 6.30