Crossbow
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*Our design suggestions include reducing the number of parts and material amount used to make certain components. This is supported by the DFE analysis, which points to high material costs. | *Our design suggestions include reducing the number of parts and material amount used to make certain components. This is supported by the DFE analysis, which points to high material costs. | ||
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Revision as of 17:20, 1 February 2014
Contents |
Executive Summary
Major Stakeholders
Product Use
Assembly with Parts Labeled
Mechanical Functioning
Bill of Materials
DFM/DFA
DFE Analysis
| DFE Guideline | Good Aspects of Competitor Product and Ideas for Improvement |
|---|---|
| 0. New Concept Development | Remove fasteners to allow a snap-fit design.
Integrate a quiver into the crossbow itself, instead of having it as a separate part. Add a loading mechanism that does not require a very significant force input from the user. |
| 1. Select Low Impact Materials | Crossbow:
Aluminum, Fiberglass, Steel Bolt: Aluminum, Carbon Fiber Sling: Nylon, Foam
|
| 2. Reduce Material Amount | Slots in the crossbow body reduce mass
Limb is removable to reduce transport volume The "snap-fit" design would reduce material amount by removing the need for fasteners |
| 3. Eco-Manufacturing | Camouflage is wrapped, but powder coating may offer some advantages.
Manufacturing requires no welding or soldering. Very little machining is used. The body is manufactured via injection molding, as evidenced by visible injection pins. Using recycled aluminum instead of virgin aluminum may offer energy savings. |
| 4. Optimize Distribution | Packaging is very minimalistic. |
| 5. Reduce Use-Phase Impact | Crossbow is human-powered using potential energy.
All parts are reusable. |
| 6. Maximize The First Life | Reliability and durability are increased by having a very simple design.
Scope and scope accessories are easily replaceable, but the device still has room for improvement regarding modularity. The grip and stock could be more easily removable. |
| 7. End of Life | Crossbow and bolts are either retired or discarded. |
Product Life Cycle Analysis
| Life Cycle Stage | Description | Inputs | Outputs |
|---|---|---|---|
| Material Extraction |
Raw materials are processed and made into materials that can be used for manufacturing. |
Iron Ore Aluminum Ore Petroleum Silica sand Limestone Polyacrylonitrile (synthetic) |
Steel Aluminum Fiberglass Plastic Carbon Fiber |
|
Production
|
Manufacturing materials are made into components. |
Steel Aluminum Fiberglass Plastic Carbon Fiber | Components |
| Use |
Archery, Hunting | Crossbow, Bolts | Shooting Crossbow |
| End of Life | Retiring/Disposal | Crossbow, Bolts | Landfill |
| Transportation | Airplane, Boat, Truck | Fuel, Crossbow, Bolts | Crossbow, Bolts |
EIOCLA
The economic input-output life cycle assessment (EIOCLA) was used to determine the environmental impact of the production of an individual crossbow and to gauge whether or not a CO2 tax would affect the economics of this product. A baseline economic activity of $1,000,000 was used for data generation and then later scaled down in order to generate more relatable data.
| Item | Crossbow | Bolts |
|---|---|---|
| Sector # and Name | 339920
Sporting and athletic goods manufacturing | 339920
Sporting and athletic goods manufacturing |
| Reference Unit | 1 crossbow | 1 bolt |
| Units consumed per product life | 1 crossbow | 6 bolts |
| Retail cost per unit (2002) | $121.00 | $25.70 |
| Lifetime cost | $121.00 | $25.70 |
| Sector mtCO2e Per $1M | 613 tons | 613 tons |
| Implied mtCO2e per Product Life | 0.074 tons | 0.016 tons |
| CO2 Tax @ $30/mtCO2e | $2.23 | $0.47 |
DFE Conclusions
- The dominant source of GHG emissions from this product stem from its production, particularly power generation and supply. Power generation and supply make up 34.1% of the Sporting and Athletic Goods Manufacturing Sector (339920).
- A $30/tCO2eq tax increase would add $2.70 to the lifetime cost of the product, which is only 1.84% of the total cost. As a result, it is fair to say that it will not affect product sales.
- Sporting goods and manufacturing are a very diverse sector, so there is a considerable amount of aggregation uncertainty.
- Most emissions related to this product are indirect, as only 3.58% of emissions come from the Sporting and Athletic Goods Manufacturing Sector (339920).
- Our design suggestions include reducing the number of parts and material amount used to make certain components. This is supported by the DFE analysis, which points to high material costs.
