Material and information flow in flexible manufacturing cell.

Mudrikova, Andrea ; Kostal, Peter ; Velisek, Karol 等

Abstract: The flexible manufacturing cell is manufacturing system contain some CNC tooling machines which are served by industrial robot. This system are designed to manufacturing of group of similar workpieces. This system is characterized by its internal material and information flow. The manufacturing proces is complex dynamical proces include technological, manipulation and control processes.

Key words: material flow, information flow, flexible manufacturing, automation

1. INTRODUCTION

The production strategy in the second half of 20th centuries was characterized by effective using of dedicated machines and automated lines. The goal was be achieve a maximal volume of production. The small shortening if production cycle has significant effect to production volume in mass production. Today market is characterized by strategy of consumer's individualization. This strategy is oriented to consumer's requests. Consumers want new products and time has fundamental task to its satisfaction. The production was broadening, innovation cycle is shortened, and the products have new shape, material and functions. At this strategy is most important parameter the time and improving is its shortening. The production strategy focused to time need change from traditional functional production structure to production by flexible manufacturing cells and lines. Production by flexible cells (FMS) is a most important manufacturing philosophy in last years. This philosophy is based on similarity:

* similarity of manufactured parts,

* similarity of process plans.

Recognize the similarity of manufactured parts allow grouping them to groups by machines required to its manufacturing. By manufacturing of this group of parts we achieve economical effect near to mass production.

By some study is existing manufacturing capability of machines used only 30 to 40%. The other resources say that technological processes spend only 5% of time needed to manufacturing. The rest of time is spending by manipulation, transport and storage.

2. FLEXIBLE MANUFACTURING SYSTEMS

The flexible manufacturing cells are characterized by high level of manufacturing process automation. They are used mainly in middle batch production (500 - 2000 pieces of products) and for middle products range (5 - 100 types of products). The supplementary devices are used mainly to manipulation with workpieces and tools:

* workpiece storage and device for workpiece changing,

* storage, controlling and changing of tools,

* quality control.

Today flexible systems are designed as manufacturing systems or as assembly systems. External manipulation devices--industrial robots, realize manipulations by workpiece in today flexible systems.

One of most modern direction of manufacturing control development is implementation a self-organizing algorithm to manufacturing process. The base of self-organizing manufacturing systems is an idea that all parts of manufacturing system will communicate with control system of whole manufacturing system. The control system has some degree of freedom and its can doing some autonomous decide in manufacturing process to achieve a better efficiency of manufacturing.

Very important field of today research is automation of storage and transport systems operations and integrate this systems to manufacturing system by common control system

[FIGURE 1 OMITTED]

2.1 Flexible manufacturing cell at Institute of manufacturing systems and applied mechanics

Building a model of integrated flexible manufacturing and assembly system for small batch production represent a new philosophy for design of complex manufacturing. This approach is representing a flexible manufacturing system that manipulate by workpieces, machining some workpieces for final product and assembly this parts to final product. Different from traditional manufacturing and assembly systems is that all of these operations are realized in one workspace.

The most important characteristic of this system is that this system not use external industrial robot to manipulation and assembly. Exchangeable end effectors for manipulation and assembly are placed at arm of device. Other end effectors are stored by end effectors storage. (Fig. 1)

We expect better efficiency of this device as a classical flexible manufacturing systems.

The prototype (model) of flexible manufacturing cell at our institute is a device which will integrate 5 manufacturing phase for all products. These phases are fellow:

1. semi product store and its transport to manufacturing device,

2. machining of semi product and its quality control,

3. manipulation by several parts,

4. assembly the parts to final product,

5. manipulation with final products and its send off to storage.

All of these phases will be solved independently but with respect to relations by other phases. The device will contain 3 connected parts:

* shelf storage with manipulator,

* rotary feeding device,

* multi functional manufacturing device.

In base of this trend we introduce new non-traditional model of integrated flexible manufacturing system for small batch production. This system doing manipulation with workpieces, machining its for concrete final product. These final products are assembled by this system and send off to storage. This conception of manufacturing system is different from the traditional system because has only one workspace and in this workspace are realized all manipulation, machining and assembly operations without an external industrial robots. (Velisek et al., 2005)

3. LOGISTICS AT FLEXIBLE MANUFACTURING CELL

For material and information flow description in flexible manufacturing cell we must define product types. We must take attention to several facts:

1. to project of manufacturing system has impact manufacturing devices by its physical and technological dimensions, Physical dimensions and weight give claims to workshop floor area.

2. material, dimensions and weight of workpieces--give a claims to power dimension of machines and manipulators.

3. technological process plan for manufacturing and assembly--machine types, tools, clamping devices, end effectors.

4. In the workshop must be situated transport devices, communications for operators and several transport vehicles.

The manufacturing logistics solve tasks about organization of material and information flow in manufacturing. The material supply processes supplying by material the manufacturing processes, by components the assembly processes and by final products the storages. Include all tasks by material and information flow of raw material from storage to manufacturing, semi finished product and bayed parts from storage across a several steps of manufacturing processes, assembly to final product storage.

This is all related to workpiece, tool, waste and envelope materials transport at manufacturing processes.

Failure free, effective and transparent material flow is achieved by stable and safe information flow. To material flow optimize has significant impact information system of manufacturing. This system has a crucial position in logistics. Before and after all material movements must be realize the information movements. These steps are needed to capability of information system serve actual and real information about a process in base, which can take a decides. (Hruskova & Matusova, 2006) Tasks to optimize the transport routes, choice of optimal manipulation and transport devices and launch a higher level of automation to transport and manipulation are most important for all manufacturing, because in these fields are covered resources to decrease manufacturing costs.

By automation level increasing in manufacturing processes, increasing the importance of choice manipulating and transporting devices in manufacturing system design time. The importance of manipulating and transport devices are underlay fact that more than 50% time needed to manufacturing are spend by manipulation and transport and automation level of this processes are smaller than automation level of technological processes.

Manufacturing process of components, parts or final products usually are not realized at one workplace. At our model of flexible manufacturing system are realized this operations in the one workplace. The part must be positioned, rotated, moved so must be realized manipulation by its. This task is named as manipulation between operations. Critical point of view to design this type of manipulation is a set of workpieces, a needed material flow and manufacturing process organization. The effective solution of this task demands a shortest material route. Need achieve a minimal running time for each manufactured part. In design time of this type of manipulation must be accepted some rules:

* solve manipulation between operation as a part of manufacturing process,

* remove all unnecessary manipulations, because manipulation increase the costs but don't increase value of product,

* by manipulation movements fellow material flow,

* material flow must be linear and simply,

* use a maximal speed of manipulating devices to decrease manipulation time,

* decrease storage area,

* use universal units for manipulation and transport,

* minimize type of manipulating devices,

* use reliable and simply manipulating devices,

4. CONCLUSION

The cell manufacturing becomes in last years one of most important manufacturing type. This conception is based on relation between manufacturing cell--workpiece. Flexible manufacturing cells allows manufacturing the small numbers of part from huge range of types and achieve good economical effects near by large batch or mass production. The manufacturing cells structure has connected the machines and save the production time, space and production costs too. Functions of machines are coordinated and the material flow can be quick

Manufacturing process of components, parts or final products usually are not realized at one workplace. The manufacturing logistics solve tasks about organization of material and information flow in manufacturing. The importance of manipulating and transport devices are underlain fact that more than 50% time needed to manufacturing are spend by manipulation and transport and automation level of this processes are smaller than automation level of technological processes.

This paper was created thanks to the national grants:

VEGA 1/3193/06-Multifunctional manufacturing and assembly cell.

VEGA 1/3164/06-Using of intelligent fixtures in manufacturing and assembly processes.

5. REFERENCES

Hruskova, E.; Matusova, M. (2006) Fixture model creation in software Catia V5R15.-1/3193/06, 1/3164/06. Proceedings of International Conference RaDMI 2006. Budva, Montenegro, 13-17.Sept. 2006.--Trstenik.--ISBN 86-83803-21-X. - S. 1-4

Kostal, P.; Hruskova, E.& Velisek, K. (2007) Clamping fixture for flexible manufacturing cell. Academic Journal of Manufacturing Engineering. No. 2 (2007), pp. 61-64 ISSN 1583-7904.

Velisek, K.; Kostal, P.; Javorova, A.(2005) Flaxible assembly cell. Proceding of 4th International conference ICAMaT 2005, Editor: C. Doicin, pp.479-482, ISBN 973-27-1254-6, 3. - 4. november, 2005, Bucharest, Romania, The