Design For Disassembly (DFD) Guidelines during an Original De

Design For Disassembly (DFD) Guidelines during an Original Design
Exercise 6.5
During the design of a product stage, designers consider the manufacturability of the components as well as the user experience of the product at the intended place of use. This leads to many considerations that designers include in their designs for optimality of the desired properties. Design for disassembly refer to the considerations in the design, which influence a products ease of dismantling thereby ensuring its ease of servicing, maintenance and the recyclability of parts (Zheng, Li and Shchukin 65) (Alshaikh 1).

Design for disassembly minimizes different types of material that are incorporated in making a product. As a result this simplifies the recycling process to ensure that the components that can be reused are easy to isolate from those that cannot be recycled (Alshaikh 13).
DFD ensures that sub-assemblies and connected parts are made from the same materials thus reducing the assembly time. This can be visualized in vehicle manufacturing where most components are preferred to be from metal to ensure ease of compatibility and joinery during assembly time. Moreover, with products optimized for disassembly in their design phase ensures that recyclable parts are made thus minimizing waste during the end time of the product. As such it is notable that a products salvage value will be higher if most of its parts are recyclable to be used in other product parts (Shetty 34) (Zheng, Li and Shchukin 85).
Design for disassembly enables standardization and, therefore, making it easy to identify the materials thus maintains maximum value of recovered materials. Standardized materials will have alternative applications as well as offering a cheap and easily available option for spare parts. DFD enables designers to minimize number of fasteners in different parts thus reducing assembly time. A more solid product will usually have less handling in the production line as opposed to a more disintegrable product, which requires a vast number of fasteners to complete the unit. This technology enables the use recycled materials since they can be easily transferable from a salvaged product to a new one hence stimulating a recycling market (Shetty 233).
DFD enables the use fasteners that are easy to remove thus reducing the time required to disassemble the components. While flatter bolts find   it hard to penetrate holes, design modifications using tapered bolts ensures that a speedy placement of nut and penetration to a hole is enabled by correctly locate their way. Depending on the various products, designers may use DFD to develop snap fits for products that require dismantling quite often such as the battery cases for cell phones. The use of fasteners material compatible with the materials of parts enables for compatibility and strength. This can be used to eliminate adhesives that may be contaminants if they are incompatible with the material. Since some applications like food handling equipment may be chemical sensitive, the joining of parts may be optimized for the most suitable fastening technologies (Shetty 81) (Alshaikh 2).
DFD enables designers to minimize the number and length of interconnecting wires or cables one by providing holes through sheets and ways through walls for shortest wire connecting distance within a product. This may be, therefore, reducing the time to remove flexible cables and also the amount and cost of cable material to be used. By doing so it’s easy to minimize parts hence reducing the overall production cost of the product DFD enables designers to make designs as flexible as possible to allow for servicing and upgrading options and Locate parts with the critical functionality in easily accessible places for less disassembly and optimum returns. In design, by placing a commonly accessed component like the car battery in an accessible location reduces the servicing times and thus speeding any handling and separation  process be it in manufacturing, installation or consumer  use of the product (Alshaikh 13) (Zheng, Li and Shchukin 45).
DFD ensures that molded metal inserts or reinforced elements are avoided in plastic parts thus reducing the need for separation of parts for recycling. Designers are able to locate non-recyclable parts that can be quickly discarded in one area to speed disassembly. Disassembly and training speeds can also be enhanced by making use of logical access and break points in a structure Ease of assembly (Alshaikh 2) (Zheng, Li and Shchukin 87).
In conclusion, the use of DFD leads to  Ease of disassembly, Ease of servicing, Ease in recycling parts, Reduction in production costs, Prolongs a product useful life, mobility of Big parts, makes it Easy to clean and service the product, increase Component reusability and Reduces product fragility (Alshaikh 3).

1
2
3
4
5
6
7
8
9
10

Part number
description
No. of items
Alpha + beta symmetry
Manual handling code
Manual handling time
Manual insertion code
Manual insertion time
Total assembly time
Theoretical no. of parts

1
Axle
1
180
1-0
1.43
6
5.5
6.93
1

2
Tire
1
180
8
1
8
6
7
1

3
Front spring plate
1
0
1-0
1.88
1
1.5
3.38
1

4
Front spring
1
540
1
1.5
2
4
5.5
1

5
Hex bolt
4
360
1-0
1.5
0
2
14
1

6
Front pillar
1
360
3
6
8
6
12
1

7
Wheel bracket
1
540
1-0
4.1
2
5
9.1
1



10





57.92





Exercise 5.6





Calculating design efficiency;
Design efficiency
Therefore from the diagram there are 3 functional units i.e. the axle, the tire and the wheel bracket
                            =3×10/57.91
                            = 51.8%

To achieve higher design efficiency this cartwheel assembly requires redesigning.
Therefore, to improve efficiency is to carry a part count reduction. This is achieved by eliminating fasteners by joining the wheel bracket to the front pillar. By having the front pillar and the wheel bracket as one component, there is the reduction in use of fasteners and thus handling the whole unit as one reduces handling times of the whole assembly. The manufacturer will also be saved the cost of casting or machining two different components by doing such a job in a single pass. This would result in a single assembly. By doing so the handling time of handling the whole unit would be saved 12 minutes from eliminating a separate front pillar and an additional 14 minutes from the handling of the hexagonal bolts. Replacing the hex bolts with a snap mechanism will be unreliable since it would greatly impact on the efficiency of the functional components.













Works Cited
Alshaikh, Mustafa. Product Design for Engineers. cengage: Cengage Learning Incorporation, 2016.
Shetty, Devdas. product design for engineers. Boston MA: Cengage Learning, 2016.
Zheng, Di, Guofu Li and Valery Ya Shchukin. Advances in Engineering design and optimization:selected peer reviewed papers from the international conference on engineering design and optimization. Durnten Zurich: conference publishers, 2012.