Product disassembly quality according to selection scenario.

Lazarevic, Milovan ; Ostojic, Gordana ; Jocanovic, Mitar 等

Abstract: Focus of this research is how the availability of lifecycle information associated with products affects the performance of end-of-life disassembly processes. Also, intention is to study the impact of (none) availability of product information, and general understanding of information (none) availability on decision making efficiency, and make a suggestion how this problems could be salved.

Key words: disassembly, recycling, selection scenario

1. INTRODUCTION

Recycling is suggested to be a supporting process to the sustainable development and an instrument to overcome a pollution and depletion of natural recourses problems. Recycling is a term that is mostly related to recycling of product and material. Product recycling implies reuse of already used, repaired products, individual components (parts/subassemblies) with the same, or some other purpose. Reuse of some components (part/subassembly) gives an advantage to recycling in a sense of avoiding or lessening thorough energy and emission into the environment, which originate from production and consumption during material prefabrication. Reuse could be defined as secondary usage of product or (mostly) parts-subassemblies, in new one, repaired or serviced products. Material recycling is related to the product recycling through process reconditioning of basic material for production new one or some other products. However, before recycling electric, electronic equipment and different products that contain dangerous components and materials--products that succumb to Waste Electrical and Electronic Equipment (WEEE) and Restriction of Hazardous Substances (RoHS) directives, needs to be disassembled. Disassembly has imposed itself as a necessary step at final dispose of products that are at the end-of-life.

Disassembly process could be defined as a product separating process of its ingredients or subassemblies, including analysis of a product condition and selection of separated components. Disassembly is always a group of operations, accomplished by using adequate tools and fixtures, in technological systems. Disassembly and recycling cannot be regarded separately. Developments in the disassembly field have considerable importance for recycling processes and vice versa.

All products admission in disassembly systems today have one common problem--lack of any information needed for their disassembly. This paper will represent current situation in already mentioned field and how disassembly influences the product quality. In addition, will be represented research results and conclusions, which have outcome of work in the laboratory conditions.

2. DISASSEMBLY SYSTEM INFORMATION

There are a many research centers for disassembly problems. The only purpose of some of these centers is disassembly process research and exploring all the possibilities for development of robotized and automated systems. This type of systems has no commercial purpose (Kim et. al., 2005).

There are systems, which are established for the purpose of dealing with the problems of waste accumulation (e.g. PC monitors, air conditioners, refrigerators, etc.). The financial effect of those systems is in question. Another type of disassembly system is designed with the purpose of achieving great financial effects. In addition, they have research purpose. Information gathered from these systems is very important for the further analysis, and they are embedded in new developed products.

All these systems and feedback information gathered from them have great importance for defining basic problems, which arise during planning and disassembly process phase.

2.1 Problems during disassembly process planning

Based on information gathered in already mentioned systems, disassembly process research is done in several ways that can be classified in three categories:

* optimal disassembly sequence,

* disassembly process planning,

* using mathematical model for financial and ecological disassembly process characteristics optimization.

All the researches have the same purpose, which is to profile the ways of efficient and effective disassembly process performing in technical-technological and economical sense. Product redesign, based on gathered information from disassembly system and automated and robotized disassembly process, is the best way of achieving established goals. Frequently noticed problems in work and research processes are: lack of information about product, uncertainty in quantity planning, resource availability, location, different types of products, disassembly level, uncertainty in product condition, etc. Researches of designing disassembly process and disassembly systems for several product types (electric motor, PC monitor, etc.) practiced in laboratory conditions have confirmed already mentioned observation. A specially formed research field deals with the lack of information for the disassembly process and selection of disassembled components. Further more, a suggestion was given about dealing with the problem of data acquisition and design of conditions for overcoming mentioned problems.

3. END OF LIFE STRATEGIES AND COMPONENT SELECTION

A starting point of designing disassembly system process is end of life strategies for products. Strategies for products at the end of a life cycle represent methods, which are used to conduct the general direction of products, and only suggestions are given for the management of a product at the end of a life. Studies related with the strategies of the products end of a life are numerous. The most accepted, and in its character, the most comprehensive classification of the products end of a life cycle is (Rose, 1999):

* re-use of used products (1);

* reconstruction of used products (2);

* usage of already used products for spare parts (3);

* recycling with disassembly (4);

* recycling without disassembly (5);

* dumping of the used products (6).

The choice of strategies for reconstruction of used products (2), usage of already used products for spare parts (3) and recycling with disassembly (4) indicates the need for designing the disassembly system.

After choosing the proper strategy for a given product and a sequential execution of certain procedures of disassembly, it is necessary to accomplish a selection of the disassembled components (parts/subsystems). In essence, we distinguish the next possibilities for the selection of components after the process of disassembly (Lazarevic, 2006):

* dangerous components--materials (H (hazard));

* material recycling (R);

* reusable (P);

* finishing (D);

* incinerate (I (incineration));

* waste disposal (W (waste)).

3.1 Component selection scenario

In the disassembly, the operation procedure is accomplished according to an adequate technological procedure, which is designated for every work place in particular. The procedure implies, in the most general case, the following (Lazarevic, 2006) (Fig. 1.):

* accomplishing operation with the help of appropriate tools and fixtures;

* analysis of the state and the diagnosis of the disassembled components (part/subsystem);

* selection of the disassembled components (part/subsystem) according to previously accomplished analysis of the condition and the diagnosis.

Initial problems in designing and working processes of disassembly systems are in a component selection phase. It is a result of a lack of information about products, and different product condition arrived in disassembly system. That is the reason for expansion of product design documentation with another document--scenario for component selection (Table 1). Scenario for component selection is important document not only in designing disassembly system process, but later when system is functioning. It enables dynamic correction of variant component selection (parts/subassemblies). There are many possible selection alternatives for some components (Table 1. and Fig. 1.). The reason is that products arrive in disassembly system in different conditions.

3.2 Data acquisition system supported by RFID technologies

Data acquisition for disassembly process and system design is a very slow and complicated process. Information gathered and processed are frequently unreliable with lot of uncertainties. Obtaining acceptable quality level of a product processing at the end of it's life depends on quality of gathered product information (Harrison et.al., 2004). Problems with products identification and making recovery decisions, insufficient material composition information available to recycler, inaccurate estimation of residual life and value of components, leads to inefficient manual disassembly.

[FIGURE 1 OMITTED]

There is a need for establishing design/disassembly data sharing system with the purpose of enabling clear, precise, and complete product information in real-time to all authorized users (Parlikad, 2003).

Using RFID (Radio Frequency Identification) technology as an integral part of a system will allow real-time access to the product information from any point in the supply chain. In addition, this technology enables product information to be stored by various users in their networks through the whole products lifecycle, but allow access to the information only to authorized users. Information is dynamic, but also linked to the static information stored by the manufacturers through the Internet.

4. CONCLUSION

Products arriving to disassembly centers are made more then one decade before (according to the strategies 2-reconstruction of used products, 3-usage of already used products for spare parts and 4-recycling with disassembly). They all have common basic problem, which is lack of any information about them. During the disassembly sequence and system design, it is necessary to choose product disassembly strategies and establish a component selection scenario. This is very complicated and slow process. During the disassembly process, it is necessary to dynamically correct selection of the strategy for every individual product. Afterwards, it is necessary to make a component selection according with the chosen strategy and previously prepared documentation. A scenario for component selection and selection procedure needs to be integral part of product documentation during the product development phase.

In the future, a product quality will depend on product and documentation design, especially in the field of disassembly.

5. REFERENCES

Harrison, M. McFarlane, D., Wong, C. Y (2004). Information management in the product life cycle--The role of networked RFID, Available from: http://www.autoidlabs.org/Accessed: 2006-03-21, Accessed: 2005-08-24

Kim, H., Ciupek, M., Buchholz, A., Seliger, G. (2005). Adaptive disassembly sequence control by using product and system information, Available from: http://www. elsevier.com/locate/rcim

Lazarevic M (2006). Contribution to the Product Disassembly System Design According to Acknowledged product End of Life Strategies, Master Thesis, Republic of Serbia

Parlikad, A. K. (2003). The Impact of Product Identity Information on Effectiveness of Product Disassembly Processes, Available from: http://www.ifm.eng.cam.ac.uk Accessed: 2005-07-12

Rose CM (1999). Product End-of-Life Strategy Categorization Design Tool, Accepted for publication in Journal of Electronics Manufacturing, Available from: http://www.mml.stanford.edu/1999.JEM.SPEC.Rose.pdf Accessed: 2005-03-17

LAZAREVIC, M[ilovan]; OSTOJIC, G[ordana]; JOCANOVIC, M[itar]; RAKIC SKOKOVIC, M[arija]; COSIC, I[lija] * & STANKOVSKI, S[tevan] *

Table 1. Component selection scenario (partial)

 disassembly
part modul pcs level ...... H hazard R recycle

 ...
 ...

 [P.sub.1/2]
part reuse D reman uf. I inciner W waste