This document summarizes a senior design project to improve the assembly process for chair backs. The current process of manually assembling chair backs from separate front and back pieces is time-consuming. The proposed design uses an Anti-Spin Receiver (ASR) and clips to quickly attach pre-cut chair back panels to frames. Analysis found the design would sufficiently support chair weight without compromising rigidity. Next steps include fabricating prototypes, testing, and presenting results to the client, Daniel Paul Chairs. The team created a work breakdown structure and Gantt chart to manage tasks through the next phase of the project.

1. Daniel Paul Chairs
Senior Design Project
ME 450
Adrien Raucoules
Andrew (Tim) Northcutt
Michael Massey
Dillon O’Connor
December 12, 2014
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2. • Stacking chairs are the chair of choice for most high volume public settings
• Hotels
• Restaurants
• Convention centers
• Corporate Offices
• Dependable construction
• Extensive customization options
• Stack for convenient storage
Introduction to Stacking Chairs
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3. • Most of the industry has moved production overseas
• Many aspects of the production are becoming more modernized
• Modernization has allowed some of the work to return to the United States
• However, a critical aspect of production has resisted modernization
• Chair back assembly has not experienced substantial improvement since 1953
Production of Stacking Chairs
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4. • Most chair backs are made with a “sandwich” construction, where separate front
and back pieces are upholstered and attached to one another
• Requires a skilled laborer to perform this task manually
• Tremendous range of customization options for chair back shape, material,
cushion, and upholstery
• Growing number of styles and combinations of chair backs as customers
demand more and more
• Each chair back is a significant investment of time
The Problem
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5. Sandwich Construction
Wood Panels without Upholstery Wood Panels with Upholstery 5

6. • Clean and professional appearance
• No mounting hardware is visible to the user
• Staples are safely contained between the two pieces
• Most of the seam between the two pieces is hidden
within the frame of the chair
• Upholstery appears seamless
Finished Sandwich Chair Back
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7. Functions and Requirements
• Not compromising the rigidity of the chair itself
• Decrease the time of assembly
• Increase production of as many chair styles as possible from the 2000 series
tubular steel frame chairs (with wood backs) from 12 per hour to 13~15 per
hour
• There are currently 31 total frame styles in this series
• Increase production of as many chair styles as possible from the 2000 series
aluminum frame chairs (from China) from 5 per hour to 6~8 per hour
• There are currently 25 total frame styles in this series
• As many back styles as possible with these frames
• Does not have to work for every design 7

8. Economizing Rigidity
• The more points of connection to the frame means better rigidity
• More points of connection means more parts and time spent making the
connection
• Stronger materials and/or a greater amount of material used in mounting hardware
(nuts, bolts, clips, fasteners, etc.) factors into rigidity
• Stronger materials or a greater amount of material comes at a higher cost
• Find a balance between time and cost of mounting hardware and rigidity of the
chair back
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9. Brainstorming
• Injection molding
• Clip mounting tool
• Uniform hole pattern
• Grid pattern
• Asterisk pattern
• Clip modification
• Extended clips
• Universal sheet with Anti-Spin Receiver (ASR)
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10. Dead on Arrival
• We thought some injection molded designs would be ideal for mass production
• Molds are very expensive to design, and there are too many different backs that
would need separate molds
• Production of individual styles are not large enough to alleviate the initial
expense
• We thought a clip mounting gun or lever based machine would help save time
applying clips to chair frames
• Design of such equipment would be difficult
• The amount of time potentially saved here was deemed trivial
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11. Dead on Arrival
(Continued)
Lever Based Clip Application Machine Injection Molded Parts
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12. Uniform Hole Pattern - Grid
• A sheet of material with a grid pattern of holes that could be mass produced
• Almost any chair back shape could be cut out and the holes would already be in
place for mounting to corresponding chair frames
• Excessive hole count would compromise rigidity
• Intended for injection molding where holes are made as part of
the mold
• Wood requires additional time and expense of
CNC machining each hole
• Unused holes equate to wasted machine time
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13. Uniform Hole Pattern - Asterisk
• A sheet of material with an asterisk shaped pattern of holes that could be mass
produced
• Work similarly to the grid hole pattern but with less holes and greater material
thickness around holes to avoid a loss in rigidity
• Intended for injection molding where holes are made as part of the mold
• Wood requires additional time and expense of CNC machining
each hole
• Unused holes equate to wasted machine time
• Thickness variation around the hole pattern is not feasible
• Possible companion to an extended clip design 13

14. Extended Mounting Clip
• A longer clip with an assortment of holes to facilitate connection to chair back
faces regardless of frame geometry
• Increased size of clip improves rigidity of chair back
• Requires more material (at the thickness of current clips) to make and thus is
marginally more expensive
• Not substantial enough an improvement in production
time to validate the cost
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15. Anti-Spin Receiver (ASR)
• Mr. Barile expressed concern with current fasteners that spin while mounting chair
backs
• Hinders tightening of bolts
• Can snag loose strands of upholstery
• Suggested a plastic receiver in an oblong shape to prevent spinning
• Provided a preliminary prototype for reference
• We dubbed this design the Anti-Spin Receiver (ASR)
• Compatible with barbs that help in the upholstery process as well as threaded bolts
• Includes a slot for variable adjustments 15

16. Anti-Spin
Receiver
(ASR)
(Continued)
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17. Uniform Hole Pattern - ASR
• A sheet of material with a standard pattern of holes that could be mass produced
and work for a variety of chair back styles is still a goal
• However, the hole pattern can accommodate the ASR
• Must work with wood
• Compatibility with injection molding for future endeavors is desirable
• Must have a lip at outermost perimeter of chair back for upholstery process
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18. Idea Cost Ease of
Manufacturing
Rigidity Efficiency
(Time)
Total
Grid Hole Pattern 2 3 3 7 15
Asterisk Hole Pattern 3 3 5 7 18
Extended Clips 3 7 7 5 22
ASR Hole Pattern 7 8 5 7 27
Scored 1 (poor) through 10 (great)
5 represents no change from current methods
Concept Selection
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19. Narrowing the Field
• Variety is an understatement about possible chair styles
• Daniel Paul Chairs offers an immense variety of
stacking chair styles with very different chair backs.
However, some chair back styles work for multiple
frames
• The chair backs shown in models 2125-RFP-RGG,
2165-HH, 2155-HH, and 2115-HH are used in 21 of
31 steel frames and 13 of 25 aluminum frames
• Model 1900-HH has a simple chair back that can be
used for future steel and aluminum chair styles 19

20. Rectangular
• Demonstrated in frame 2125-RFP-RGG
• We call this chair back style the “rectangular”
chair back
• Named due to its basic four sided shape
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21. Taper
• Demonstrated in frame 2165-HH
• We call this chair back style the “taper” chair
back
• Named due to its basic four sided shape with
a mild taper along its height
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22. Oval
• Demonstrated in frame 2155-HH
• We call this chair back style the “oval” chair
back
• Named due to its basic shape
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23. Ghost
• Demonstrated in frame 1900-HH
• We call this chair back style the “ghost” chair
back
• Named due to its shape, which we felt
resembled a traditional ghost
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24. Lady
• Demonstrated in frame 2115-HH
• We call this chair back style the “lady” chair
back
• Named due to its elegant shape
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25. Proposed Design
• Works for rectangular, taper, oval, and ghost chair back shapes
• We were not able to factor in the lady chair back shape
• When crafting from wood, holes can be made using standard drill bits that are
drilled in and dragged along in a straight line for 1/2 in
• 3/8 in through for body of clip
• 1/2 in to recess for lip to lie flush into the chair back
• Ideal with injection molding
• Outermost lip for each shape is discretely included in the structural webbing
• Requires one mold to be made
• Some extraneous material will be wasted 25

26. Proposed ASR
3D Model of ASR Drawing of ASR
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27. Proposed ASR Clip
3D Model of ASR Clip Drawing of ASR Clip
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28. Proposed Uniform Sheet
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29. Analysis of Proto-Prototype
Engineering analysis was done using the following
setup:
• Smallest area frame (oval)
• Using the primary chair back material as ABS
Plastic
• Assuming the ASR pieces are made of ABS plastic
and the ASR clips and chair frame are made of
extruded aluminum (Aluminum 6061)
• Thickness of frame walls is 1/16 in
• The max pressure supported by the back frame is
0.68 psi which equates to a 150 lb force over the
220 in² surface area Oval Chair Back
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30. Analysis of Proto-Prototype
(continued)
Results:
• Our analysis concludes that with proper spacing of the
ASR and ASR clips, the majority of the force is
distributed directly to the frame
• The back panel has no noticeable effect on the
performance and is merely aesthetic
• The max stress was ~40 ksi, centered around the bend of
the frame where it would attach to the base
• The max displacement appeared at the top portion of the
frame at ~3.5 in
Stress Analysis
Deflection 30

31. Preparation for Moving Forward
• Our work will continue into ME 460 in the spring
• To facilitate keeping our work on target we have established a work task
breakdown
• We have a Gantt chart to keep up with our deadlines and task progression in one
convenient diagram
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32. Work Breakdown
Structure
Gantt Chart
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33. Delegation
of Tasks
• Procure Materials - Michael Massey
• Prepare Test Plan - Tim Northcutt
• Fabricate Parts - Dillon O’Connor
• Assemble System - Adrien Raucoules
• Test System - Tim Northcutt
• Final Presentation - Dillon O’Connor
• Write Report - Adrien Raucoules
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34. Bill of Materials
Each chair would require the following:
• 1 frame of desired shape
• 1 wood/plastic chair front panel
• Cut to desired shape
• 1 wood/plastic chair back panel
• Cut to desired shape
• 6 ASR pieces
• 6 ASR clips
• 6 1/16 screws
• 6 barbed nails
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35. Cost Estimates
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36. Conclusion
• We are confident this idea can work
• However, we have our work cut out for next semester
• With the continued support from Daniel Paul Chairs and Mr. Barile we hope to
chip away at the stalemate in chair back construction
• We intend to try to verify the accuracy of our estimates about both the money
saved in materials and the time saved per chair
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37. References
• Slides 2, 6, 20-24: images courtesy of Daniel Paul Chairs
(www.danielpaulchairs.com)
• Slide 9, 19, 33: images courtesy of Google Images
• Slide 16: images courtesy of Pete Barile
• Slides 2, 3, 4, 35: information courtesy of Pete Barile
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38. Questions?
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