Integrated maintenance as profitable approach.

Pamintas, Eugen ; Turc, Cristian-Gheorghe ; Belgiu, George 等

1. INTRODUCTION

It's a global financial and economical crisis. In many countries all over the world the industry stops grows or even worst decrease or declare insolvency.

In return, only few numbers of big companies has taken the necessary step of deciding to update their operation to be able to meet global competition. This attitude in Romania contrasts sharply with that prevailing in the other country of European Union, where significantly more progress has been made in making the manufacturing sector more competitive.

To change this bad attitude, for the beginning it must carry out the specification that, the manufacturing automation and updating are exclusive concepts. For this paper, machine-tools and manufacturing equipments are our objects of interest. CNC machine tools constitute the most basic element of most automated manufacturing installations. They are becoming more flexible, more accurate, more reliable, for instance, higher uptime, and more intelligent. (Balic, 1999).

To stop and then to reverse the decline of competitiveness in the manufacturing sector, for a lot of small and medium enterprises (SME), there are some solution at hand which are relatively easy and not expensive: small automation, improving data communication using IT, re-organizes the maintenance department based on the newest concepts of active integration with manufacturing processes and also in management.

2. THE MANUFACTURING PROCESS AUTOMATION

Flexible manufacturing equipment makes it possible to almost instantaneously change the specifications of each part or product being manufactured. As a result, such automated plants are extremely versatile and are able to achieve almost the same advantages, such as high speed and low cost, as "hard" mass-production plants while producing a great variety of products of superior quality in very small batches of identical products.

It is interesting to note that, whereas the output of manufacturing will become more diversified, the equipment used in the manufacturing process will become more standardized. Product diversification will be accomplished by the software that controls the standardized, versatile equipment.

For an updated manufacturing enterprise, the accurate and timely information is the lifeblood (Narayan, 2003). Sophisticated data-collection technologies are beginning to be utilized so that allows automated equipment to function at optimum effectiveness. The information is accumulated and stored in computer memory, and is used in making decision concerning the processing, handling, identifying, tracking of each item raw materials, parts, work in process, tools, fixtures, pallets, robots, etc.

3. SENSORS--THE N SENSES FOR MONITOR AND CONTROL

The classic monitoring function includes checking and measuring automated processes to ensure that standards are met and to warn of any deviations that might require human intervention before product defects begin to occur. A modern monitoring system for manufacturing consists of a set of different sensors, controllers, interfaces, and display terminal.

Generally, the system is a no contact device that can "scan" an entire process at once, determine patterns, and discern subtle details. Over the past decade or so, machine monitoring has made rapid progress Machine monitoring systems have found wide application in automated manufacturing installations. Specific functions typically performed by machine monitoring systems include: inspection, monitoring, positioning, adjustments, machine-man communication, self-repair decision or requesting of the corrective maintenance scheduling and control of all over the manufacturing process (Buttler, 1992).

[FIGURE 1 OMITTED]

Automated sensing devices provide an essential link in an automated manufacturing installation by collecting raw data from the manufacturing process. When combined with computer power, they can perform a large variety of functions, including identification, inspection, monitoring, maintaining inventories, and control. There are a large variety of both contact and no contact-sensing devices that find application in an integrated monitoring and control system as in figure 1.

There is one other technology that should be noted in connection with total monitoring process-digital process data. By combining digital process data with CAD/CAM techniques, it becomes possible to solve problems and technological details that would otherwise be impossible to the human mind. Digital data is used in high-value applications (Kondoh et. al., 1998).

It is expected that the use of automated sensing devices--and especially of machine monitoring systems--will increase significantly over the years ahead.

4. INTEGRATED MAINTENANCE

As an intermediary step to total productive maintenance (TPM), we propose the terms Integrated Maintenance System (IMS). What is new in this approach? Let's briefly review the domain. 50 years ago the concept of preventive maintenance was advocated, and time-based maintenance (TBM) was introduced. In the 70's of past century, when the machine diagnostic techniques where introduced, another concept named CBM (condition-based maintenance) was developed. It follows the breakdown maintenance (BM). In order to select the proper maintenance strategies, on the last decade of the XXth century a lot of methodologies for this purpose were attempted: Reliability Centred Maintenance (RCM) (and Risk Based Inspection (RBI) or Risk Based Maintenance (RBM) (ASME, 1994).

[FIGURE 2 OMITTED]

A method to improve the maintenance department image and to emphasis its role to control the conditions of manufacturing process and to provide the functionality required under the imperative of increasing the enterprise's profits, is the Integrated Maintenance System (IMS).

For a small company that produce mechanical parts for automotive industries, a new architecture of the maintenance system, as is shown in figure 2, was propose and then adopted. Is a stage to a future total integrated system for manufacturing process monitoring & maintenance, composed of four plus one feedback loops which provide a great range of independence and flexibility also during entire product life cycle.

An IMS can offer many advantages over classical maintenance systems: they require less space and fewer workers; they reduce product damage and pilferage; they result in more accurate inventory management and control; and they provide easy accessibility of all items at all levels of a manufacturing system and faster and more reliable delivery of final product. The two main disadvantages of IMS are the difficulty of modifying and expanding the system, especially no automated devices auxiliary to the main manufacturing systems, and their capital cost.

In order to reach an IMS as that presented in figure 2, the future research will be focused on the implementation of an integrated monitoring & control system based on a CNC lathe. The CNC machine tool will be endowed with a set of different sensors (for temperature, vibrations and forces). The taking over of technological data from the lathe computer and the data acquisition from sensors will be uses by a new software based on an algorithm with 3 feedback close-loops (as a first step), with the purpose to process monitoring and optimise the maintenance decisions.

5. CONCLUSION

In this paper, we have discussed the integrated maintenance as a profitable approach not only for small and medium enterprises but also for big company, and not only for now days economically crisis but for all life of the companies. The proposed IMS pre-concept provide a high quality for the processes and products being an ease intermediary step to the automated factory of the future in which the maintenance activities are with respect to entire product life cycle management. The monitoring stand can be developed in a veritable research laboratory not only in maintenance but also in the manufacturing process automation.

6. REFERENCES

Balic, J. (1999). Contribution to intelligent manufacturing, DAM Publishing Series, ISBN 3-901509-03-8, Vienna, Austria

Buttler, H. (1992). Model reference adaptive control from theory to practice, Prentice Hall, ISBN 0-13-558 286-9, London, UK

Kondoh, S., Umeda, Y., Yoshikawa, H. (1998).Development of upgradable cellular machines for environmentally conscious products, CIRP Annals, 47/1

Narayan, V. (2003). Maintenance Management: risk and reliability strategies for optimizing performance, Industrial Press Inc., ISBN o-8311-3178-0, New York, 2003

***ASME. (1994). Risk-based Inspection--Development of Guidelines, Vol.3, ASMEResearch Report, CRTD.Vol.20-3