Folding Desk Chair Innovation
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===DFE=== | ===DFE=== | ||
Revision as of 21:22, 3 May 2012
Contents |
Executive Summary
Market Analysis
Relevant Market Research
Survey
Retailer Interview
Prototype User Study
Other Market Research
Competitor Products
Cosco Upholstered Folding Chair
Chair with Writing Tablet
Folding Chair with Writing Tablet
Target Market
Price, Cost, & Profitability
Price
Cost
Profitability
Design Documentation
Bill of Materials
| Part # | Part Name | QTY | Weight (g) | Function | Manufacturing | Material | Image |
|---|---|---|---|---|---|---|---|
| 1 | Folding Chair | 1 | Provides user with comfort and support. | Purchased from McMaster-Carr, part # 4821T3 | steel | ||
| 22 | Turntable | 1 | Attaches desk surface to table support and allows desk to rotate 90 degrees for folding. | Purchased from McMaster-Carr, part # 1797K3 | Steel | ||
| 23 | Desk Arm | 1 | Attaches desk to chair and rotates between open and closed position. | Bent pipe | Steel | ||
| 24 | Hinge Top | 1 | Allows table to open up for folding. | Stamping and folding. | Steel | ||
| 25 | Hinge Bottom | 1 | Allows table to open up for folding. | Stamping and folding. | Steel | ||
| 26 | Table Support | 1 | Attaches hinge to desk surface. | Cutting. | Aluminum | ||
| 27 | Desk top | 1 | Serves as a desk surface. | Injection Molding | HDPE | ||
| 28 | Links | 2 | Stops the desk arm at the appropriate angle. | Cutting and stamping. | Aluminum |
House of Quality
Design Analysis
DFMA
Design for Manufacture and Assembly considerations were significant to the prototype and design analysis. As the DFMA implications are expanded to the large scale production regime, several conclusions become apparent. If implemented on a large scale, the folding desk chair would be composed of two major subassemblies: a stock folding chair (likely very similar to the black Target brand model used in our physical prototype), and the custom desk and arm sub assembly. This means that other than the simple variations made to the folding chair (holes to mount hardware) after assembly in its own factory, all DFMA considerations for this project lie in the desk, arm and hinge sub assembly. Even on the large scale, we would have little to no control over DFMA in the chair.
The following is a description of some of the major DFMA considerations made for our prototype and hypothetical production-scale model. Firstly, stock tubing is used to form the main pivot arm. In this and all cases, use of fasteners is minimized by using as few parts as possible. In this example, bending stock tubing is the simplest way to make the custom shape of the arm. Attaching the main arm to to the chair and hinge on each end is also done using DFMA considerations, by using rivets and spring pins rather than traditional fasteners. This is because fasteners such as rivets and pins are easier to install, cheaper, and their inherent drawback of permanency doesn't matter in this use. Once the chair is assembled, it need not be disassembled. The hinge that allows the desk to open and close is a unique shape, but still only composed of two folded sheet metal pieces hinging on rivets. The interface between the support arm and the hinge is also hinged using a rivet, which is strong and easy to manufacture.
FMEA
Failure Mode Effects Analysis was the largest and most important aspect of the Design Analysis facet. In order to customize the analysis to our design, the group focused on
DFE
To further analyze the competitiveness of our design solution, we conducted an economic input-output life cycle analysis of our product. Once again, after initial analysis, we found that the majority of the environmental impact of our product is the result of the production and manufacturing phase. Thus we chose several sectors that best represented our product. Once again we had the retail price of the chair. For the pricing of the additional new parts we either used resources such as McMaster-Carr or custompart.net to estimate a cost. Using all this data we ran a new EIO-LCA the results of which can seen below.
Once again, we found that the total CO2 tax would be less than 2% of the cost of the product. Not only is this insignificant in terms of our current product, but it is also about the same as our original folding chair, meaning that it is equivalent to what is on the market today.
| Production | ||||
|---|---|---|---|---|
| Chair | Desk Arm | Hardware | Desk Surface | |
| Sector | 33712A Metal and other household unupholstered furniture | 332996 Fabricated pipe and pipe fitting manufacturing | 332500 Hardware manufacturing | 32619A Other plastics product manufacturing |
| MTCO2E per $1M | 613 | 796 | 600 | 748 |
| Unit | chair | arm | hardware | desk surface |
| Unit per lifetime | 1 | 1 | 1 | 1 |
| Cost per unit | $32.38 | $2.28 | $52 | $15.67 |
| Lifetime | $32.38 | $2.28 | $52 | $15.67 |
| Implied MTCO2E | 0.01984894 | 0.001797368 | 0.0312 | 0.011720412 |
| CO2 tax @$30/mt | $0.60 | $0.05 | $0.94 | $0.35 |
Mechanical Analysis
Prototype Documentation
Design Process
As our group moved towards the final design stages, our roles became a productive balance of both dynamic tasks and distinct responsibilities. Sarah's role as team leader resulted in frequent but efficient meetings, consistent reminder of the big picture and effective weekly task delegation. Similarly, although Joseph led the prototype and CAD sections, whenever the group was in either the machine shop or the computer lab, tasks were delegated and all members efficiently in parallel. Not only was this an effective use of brainpower and time, but it also ensured that all members stayed actively involved in the product across the entire semester. The transition between Will and Sarah as team leader was politically tumultuous, but resulted in a more well rounded representation of different thoughts in the group. Will continued to be very organized (keeping track of class handouts) and an active participator in weekly meetings with the professor. Tammy was in charge of most of the design analysis parts of the project. Being the best at CAD, she led the transition between accurately modeling the chair on a visual basis to making a viable model to simulate with. Despite working alone while actually running simulations, she always reported back to the group with concerns and results, which were met with feedback from the rest of the group. Mark
Lastly, an important part of our team dynamic this semester was using the group texting application, GroupMe. Set up at the beginning of the semester, it has continued to be our only resource for the necessary quick and accessible communication we did, and is much less cumbersome than long email chains.
