Case Study

Thus far, we have presented the overall structure on an innovative interactive design system that can be used to modify product design. The system can be used for any number of design goals. The design goal being dealt with in this chapter is disassembly.

In order to gain a better understanding of this system conceptually, we will present a case study of a real product in this section. The design of the product will be altered to facilitate disassembly. Design decisions will be made using the system described in this chapter. Doing so will help further demonstrate the utility value of this system.

TABLE 3.15

Bottom hatch and access panel of a typical laptop computer: Different components

Component

Quantity

Material

Bottom panel

1

Aluminium

Access hatch

1

ABS plastic

Fastening screws

5

Aluminium

Laptop main body

1

Various

Bottom panel of a typical laptop computer

FIGURE 3.12 Bottom panel of a typical laptop computer.

Let us take the case of disassembling a laptop computer for our case study. As a result of an ever-increasing need for “computing,” computers are found everywhere. Computers are so commonplace that the trend is increasingly shifting towards mobile computing. Consequently, desktops are being replaced by laptop computers in large numbers. This is the reason we picked this particular product to help demonstrate the utility value of our interactive system. It is possible for a designer to alter and modify different parts’ design of the laptop computer. Once again, the goal of this case study is to aid in disassembling the laptop computer by using the methodology presented in this chapter.

Design objective: To alert and modify the design of the bottom hatch of a laptop computer. The goal is to improve access to internal components, thereby improving ease of disassembly.

Consider Figure 3.12. The bottom panel of a typical laptop computer is depicted in this figure. The goal of the designer is to alter and modify the design of the access hatch so that access to internal components is facilitated. This will, in turn, improve the overall ease with which the laptop can be disassembled. The access hatch is usually situated in the bottom panel and serves the following purposes:

  • • Both memory modules are protected by the hatch.
  • • The hard drive is secured and protected by the hatch.
  • • The CMOS battery is secured and protected by the hatch.
  • • The wireless card is secured and protected by the hatch.

The access hatch of a laptop computer is not to be taken lightly. It is an obviously important component in view of its functionality as described earlier. As a result, it is important to design it carefully. When the design of the access hatch is modified, it will result in affecting the design of other components as well. They are presented in Table 3.15.

How is a Product Being Designed Based on Current Practice and Literature?

We have presented an exhaustive overview of design for disassembly guidelines in this chapter. We also carefully studied the literature on the topic. This study has revealed some interesting facts. We found that most disassembly related research has focused on process logistics such as product takeback and optimizing the disassembly process. It also deals with other issues such as balancing the disassembly line, ways and means to achieve maximum profit and formulation of disassembly sequence plans and so on. We have looked at the basic definition of a disassembly sequence plan earlier in this chapter itself.

These are strategies that are largely reactive in nature. As such, one gives consideration only to current design, not design modifications. Design alterations and modifications in line with design for disassembly principles are not considered. No proactive design strategies are investigated. This is what is referred to as process optimization and it does not factor in design considerations. If there are any proactive design decisions being incorporated into the design process, they only address the twin objectives of manufacturability and assembly. Also, we have already studied that not too many proactive design for disassembly tools are available in the market today.

One of the proactive design for disassembly tools we discussed in this chapter is the method presented by Kroll and Carver (1999). This method seeks to quantify disassembly effort. It is achieved by rendering it as a function of underlying design parameters. One of the drawbacks of this method is that it does not offer any means by which the component in question could be redesigned for ease of disassembly. Thus, insofar as its capacity of being able to offer design solutions, the method is found lacking. In addition, it was found to not be very user friendly because it does not easily lend itself to automation.

Consider the design guidelines formulated by Zhang et al. (1997) to enable design for disassembly. Once again, these are just guidelines, and a comprehensive methodology was found lacking. Similar guidelines were also developed by Suga et al. (1996) by formulating quantitative disassembly evaluation criteria. The goal was to evaluate a design from the perspective of rendering the product easier to disassemble.

These guidelines would enable assessment of the current design or any future designs for ease of disassembly. Numeric scores based on the quantitative criteria could be assigned to each design in order to enable design assessment. But the methodology fell short of explaining how the design modifications were to be achieved. Given the lack of a comprehensive methodology, no practically applicable design tool was proposed.

A methodology to enable automatic generation of disassembly sequences was developed by Ong (1999). Once again, as in numerous prior examples, the methodology sought to generate disassembly sequences was based on the current design. No information was provided on how to modify the existing design so that it would be easy to disassemble.

As far as we know, no comprehensive design tool is currently in existence that seeks to bring together the myriad guidelines presented thus far in this chapter. The format needs to be coherent in structure so that the information can be offered in the form of an interactive design solution to the user. The framework being presented in this chapter tries to achieve that goal.

It is intended that the interactive system will achieve design goals quickly, thus simultaneously enhancing productivity. Given the high degree of automation inherent in the process, the system will result in reducing the amount of effort and time required to achieve modifications. This will be in large part due to the way it “communicates” with existing CAD packages. System productivity can be enhanced manifold if design renderings take on the form of 3D objects instead of 2D renderings. This is because it is generally easier to visualize a design in three dimensions than in two. Doing so facilitates both component design as well as the spatial arrangement between other components and subassemblies.

One of the main characteristics of the proposed framework is that it offers multiple design solutions. Using these solutions, it would be possible for the designer to visualize and imagine a host of different design architectures. The more solutions one has, the more it is possible to use a variety of permutations and combinations to achieve better end designs. Design time is likely to be minimized given the fact that the proposed system provides solutions in a visual format. A combination of these features makes the design process less irksome.

When compared to extant design software, it will be observed that disassembly design solutions rendered by standalone CAD software using CAD packages is often inefficient and consumes too much time. The reason for this is that the designer needs to build each solution from scratch. This in turn limits the time, energy and drive of the designer, whereas in the present case, solutions are proposed by the system. As such, they are easier to visualize and can be built upon quickly. This has the effect of accelerating the design process.

 
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