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Revision as of 17:33, 23 September 2007

This product is a component of the analysis for the aquarium pump project.

Product Purpose

[Copy corresponding section from aquarium pump front page once proofread]

Customer Needs

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Stakeholders

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Consumer Demographics

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Product Function

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Product Use

In order to demonstrate the use and operation of the siphon, our group made the following video:

• Water Siphon Demonstration

Bill of Materials

Part Number	Description	Quantity	Function	Material	Weight	Manufacturing Process	Image
1	Siphon Attachment Converger	1	Joins siphon tube to attachment	Clear Plastic	0.6 oz	Injection Molded
2	Attachment	1	Cleans aquarium rocks	Clear Plastic	1.4 oz	Extruded
3	Tube	1	Transfers fluid from aquarium to output from source	Clear Plastic	4.9 oz	Extruded

Failure Mode and Effects Analysis (FMEA)

The table below details our assessment of the most common failures that we anticipate the bilge pump to experience. This assessment explains how product parts may fail and what the consequences, detectability, and probability of occurence those failures implicate. Addressing these possibilities will allows future designs of this product to be more reliable. Using the Suggested Evaluation Criteria (as found on the FMEA wiki page), we were able to rank the severity from 1-10 (10 being the highest). For the occurrence parameter, we then were able to rank the probability of failure again from 1-10 (with 10 being the highest). Finally, we were able to rank detectability from 1-10 (with 1 being the most detectable). From these three numbers, we were able to multiply them together, which results with the Risk Priority Number (RPN).

The highest RPN value for this analysis was 105, which would be caused by overuse. This mode of failure would lead to a hole or rip in the main tube, which transfers fluid from the aquarium to the output source. This failure received a 7 for severity, a 5 for probability of occurrence, and a 3 for detectability. The result of this failure would be the siphon operating inefficiently but perhaps would lead to a complete loss of functionality. From this analysis, it can be concluded that even the most catastrophic failure is not detrimental to the user with respect to his or her physical safety and wellbeing. The worst case scenario is that the siphon would lose its functionality, causing the user to have to purchase another such pump. To fix this failure mode, a possible solution would be to use more durable material in the tube. This example illustrates the fact that the FMEA analysis diagnoses some room for improvement in the overall design of the siphon.

Design for X (DFX)

The concept of DFX refers to considering a specific variable X in the design of a product. Some common variables that are considered are ease of: manufacturing, assembly, use, and maintainability.

Design for Manufacturing and Assembly (DFMA)

DFM and DFA refer to analysis and design strategies that aim to understand how a product is made and how the manufacturing and assembly steps in its production can be improved. The DFMA process is advantageous for a designer’s consideration due to the tremendous cost benefits that accompany the simultaneous analysis of DFM and DFA and the interface between the two methods. The use of these methodological tools can reduce costs, decrease labor, cut production times, decrease part counts, and improve the overall design quality.

Design for Manufacturing (DFM)

The primary goal of the DFM process is to analyze the manner in which the component parts of a product are made. By examining how things are manufactured, this process can be optimized so that parts can be produced efficiently and economically while adhering to design constraints. In order to optimize a manufacturing process, cost factors must be taken into account along with time, labor, environmental, and quality concerns. The list below details some of the ways in which DFM was likely incorporated into the design of the siphon:

• Tube and attachment are both extruded, which allows for less wasted plastic and ultimately greater efficiency and lower cost in mass production
• Tolerance between siphon attachment converger and tube is loose enough to allow small expansions of plastic tubing for tight fit in assembly, which prevents parts from being discarded owing to fitting problems
• Product contains no materials that are difficult or expensive to manipulate in manufacturing process (e.g., rubber, glass, metal)

The analysis above suggests that the product has been designed well for manufacturing. Despite its simplicity, the siphon design manages to reduce manufacturing costs through its choice of materials yet retains a high degree of durability. However, one improvement that might be made is to use an injection molding process to make the siphon attachment converger instead of forging, as this manufacturing switch would allow the process to become more cost effective.

Design for Assembly (DFA)

The objective of DFA is to improve product quality and reduce costs by optimizing a product's design and assembly process. DFA goals are predominantly achieved through simplifying a product, reducing part counts, and designing components that can be easily managed and installed. The follow list describes how DFA was probably applied to the design of the siphon:

• Product design uses sleeve fitting instead of fasteners to reduce part count, thereby decreasing cost and complexity
• All components are axisymmetric about radial axis and have enough friction to facilitate handling and manipulation
• Parts are not too big or heavy due to light plastics used in design, which makes handling easier
• Stackable nature of siphon attachment converger reduces storage space through compact design
• Simple and clear product design (with terminals that can only be connected with correct parts) facilitates assembly

From the aforementioned analysis, it is evident that great care has been taken to optimize the assembly process for the siphon. Owing to the straightforward nature of the product design, the design for assembly of the siphon is nearly optimal, as it avoids superfluous complexities and allows for easy handling.

Design for Environment (DFE)

Design for the environment refers to the concept of considering the effect that a product will have on the environment. The entire life cycle of the product should be considered. This includes the manufacturing of the product, the transportation of the product, the use of the product, and end of life.

Economic Input-Output Life Cycle Assessment (EIO-LCA)

One way to assess the effects that a product has on the environment is a process called EIOLCA. This takes into consideration each sector of the economy affected by manufacturing and distributing the product of concern. The economic activity, energy usage, and greenhouse gas emmissions related to manufacture and distribution of the product for each sector is calculated by an EIOLCA software.

For the siphon the sector of "Plastics pipe, fittings, and profile shapes" was used to analyze the environmental effects of the product. The current retail price of a siphon is $5.99, which corresponds to a retail price of $4.63 in 1997, when the data on the EIOLCA software is valid. This price can be used to adjust values for $1 million of production to show the effect that producing one bilge pump has on the environment. For $1 million worth of the product, the total economic activity for all sectors is $2.28 million and for the top five sectors is $1.315 million. This corresponds to $10.56 and $6.09 of economic activity from all sectors and the top five sectors respectively per combination of the bilge pump and siphon. The total energy required to manufacture $1 million worth of the product is 11.6 TJ for all sectors, and 6.959 TJ for the top five sectors. This corresponds to 53.71 kJ for all sectors and 32.22 kJ for the top five sectors for one bilge pump and one siphon. The global warming potential for manufacturing and distributing the product is 884 MTCO2E for all sectors and 528.3 MTCO2E for the top five sectors. This corresponds to 4.09 kTCO2E produced while manufacturing and distributing one siphon and one siphon from all sectors, or 2.45 kTCO2E produced from the top five sectors.

The following table shows the data obtained on economic activity using the 1997 purchaser price model in the EIOLCA software for $1 million worth of "Plastics pipe, fittings, and profile shapes" produced.

The following table shows the data obtained on energy usage using the 1997 purchaser price model in the EIOLCA software for $1 million worth of "Plastics pipe, fittings, and profile shapes" produced.

The following table shows the data obtained on greenhouse gas emmissions using the 1997 purchaser price model in the EIOLCA software for $1 million worth of "Plastics pipe, fittings, and profile shapes" produced.

Since there is no energy or waste produced by the product itself during use, this stage in the life cycle has no environmental effects. At the end of life, the product can be recycled since it made essentially of only plastic. While energy is used in recycling the product, the beneficial aspects of recycling outweigh this effect. Thus, manufacturing and distribution of the product has the largest impact on the environment. However, the processes and products use already minimize this effect during manufacturing so there are no environmental concerns left to be addressed in future design.

Quantitative Analyses

To pass through the siphon system the fluid will:
1. Enter attachment
2. Pass through contraction to enter siphon tube
3. Flow through siphon tube
4. Exit siphon tube

In order for the fluid to pass through this system, the fluid will have to overcome a head loss. Most of the head loss in this system comes from what is called minor head losses associated with expansions and contractions in the flow path. The below equations represent the two ways of calculating minor head loss when the mean velocity of the flow is known. Since the velocity of fluid passing through the system may vary depending on the user, the actual head loss of the system cannot be calculated explicitly.

In the first equation, K is the head loss coefficient. In the second equation, f is the friction factor (which varies with velocity of the flow), the quantity Le is the equivalent length of an elbow, and the quantity D is the inner diameter of the pipe. The relevant values for the siphon system are shown in the image to the right.