Crossbow

From DDL Wiki

Contents 1 Executive Summary 2 Major Stakeholders 3 Consumers 4 Retailers 5 Manufacturers 5.1 Product Use 5.2 Assembly with Parts Labeled 5.3 Mechanical Functioning 5.4 Bill of Materials 5.5 DFM/DFA 5.6 DFE Analysis 5.7 Product Life Cycle Analysis 5.8 EIOCLA 5.9 DFE Conclusions 5.10 Team Members

Executive Summary

Major Stakeholders

Stakeholder needs:

In the context of the weapons market, crossbows are a niche product in that space accounting for here in the US. This weapon was previously used heavily in military action, but has since dwindled in developed countries and is pretty limited to underdeveloped third world uses and not front line uses. Some of China’s riot tactics employ crossbows in addition to unique special forces regimens for quiet tactics at close range like the Spanish Green Beret’s2. Because of its scaled back military use our initial approach is to target the largest crossbow user interface: hunting and leisure. Twenty five years ago cross bows weren’t even allowed for hunting in most states and now the total count is 231; as this number is rising due to the versatility afforded to cross bow users in increment weather.

Consumers

• Cost
• Ergonomic
• Portable
• Weight
• Aesthetic
• Accuracy
• Reliable
• Ease of Use
• Ease of Repair
• Reloading
• Ease of storage
• Ease of packing
• Easy transformable (i.e. snap on/off)

Retailers

• Cost
• Overhead
• Storability
• Shelf Life
• Quality of product
• Usability of product for customers (if 23 states are ok with it for hunting, 27 are still not)
• Service center

Manufacturers

• Reliable service
• Quality control

- Materials - Longevity - Accuracy - Weight

• Ease of packaging
• Ease of use
• Dynamic function

- Portable, - Folding - Loading mechanism - Multiple functions - Wasted material

Product Use

Assembly with Parts Labeled

Mechanical Functioning

Bill of Materials

DFM/DFA

DFE Analysis

Table: Design for Environment Study

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 Replacing aluminum components with plastic could provide a net benefit for the environment.
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

Table: Product Life Cycle Analysis Results

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.

Table: Summary of CO2 Emissions During Production Phase

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.

Team Members

• Zachary Medeiros- DFE
• Spencer Lehr
• Jennifer Golda
• Nathaniel Krasnoff
• Lenny Rodriguez