How to lower cost and time for manufacturing in virtual enterprises.

Parpala, Lidia Florentina

1. INTRODUCTION

A virtual enterprise is a temporary alliance of enterprises that come together to share skills and resources in order to better respond to business opportunities and whose cooperation is supported by computer networks--challenges the way manufacturing systems are planned and managed.(Camarinha-Matos, 2002)

It is a well known fact that one product can be manufacture either using the traditional technologies (milling, drilling, turning, etc), or using alternative technologies.

In this paper I tried to make a comparison, based on time and cost parameters, between traditional and alternative technologies.

2. CASE STUDY

2.1 The traditional approach

This case study refers to an industrial product, a flange used for mounting an engine on a robot. First I have tried to manufacture this product on a traditional machine tool but also to achieve the goals of virtual enterprises which are now the most competitive. (Parpala, Popa, 2007)

I have passed this flange through the CAD/CAM/CAE modules of CATIA V5 in order to obtain a better product in less time. This custom-designed flange is made of 1/2" thick 6061-T6 aluminium and comes with eight countersunk bolts to fasten directly to a robot motor without any modifications.

CATIA Mechanical Design (figure 1) accelerates core activities of development from concept to detailed design and onto drawing production. Mechanical design products use dedicated applications that dramatically enhance productivity and strongly reduce time-to-market.

CAD module provides the tools needed to perform 3D part and assembly design and the generation of manufacture drawings, and includes integrated real-time rendering capabilities and support for data exchange using common industry standards.

CAE module (figure 2) provides the tools to engineer 3D parts and assemblies and generate production drawings. Mechanical Engineering also includes intuitive stress testing functions and integrated real--time rendering capabilities and data interfaces to the most common industry standards.

[FIGURE 1 OMITTED]

It also provides the tools to perform advanced 3D engineering of parts and assemblies, and includes intuitive design stress testing functions and advanced 3D oriented productivity features.

Mechanical Engineering is interoperable with other CATIA V5 solutions, and offers integration tools for compatibility with CATIA V4 and data interfaces to most frequently used industry standards.

CATIA NC Manufacturing (figure 3) offers basic numerical control capabilities such as tool path verification, material removal simulation, remaining material analysis, tool path edition and creation of shopfloor documentation. It provides the infrastructure for all V5 NC programming products and allows numerical control programmers or machine operators to review V5 part operations.

[FIGURE 2 OMITTED]

[FIGURE 3 OMITTED]

2.2 The Alternative Approach

In the second part of this case study I tried to prove that an integrated system as CATIA V5 and the CAM software provided by OMAX one can obtain a better product in less time and also with less costs. (Parpala, Popa, 2007)

Figure 4 presents the stages of product modelling for the flange. The first step is to make a 3D model of the part which constitutes the base for the finite elements analysis.

Topological optimization was made using FEM analysis of the part. One can observe that some sectors of the part can be cut-out without any modification of the part behavior.

The last stage of the modelling process is to redesign the part with regard to the topological optimization analysis.

The main screen of the OMAX Make software presents information over the way in which the part will be manufactured. The position of the nozzle can be seen, as well as the program summary for the machine which accomplishes the manufacturing.

In order to make a comparison between the two approaches I have tried to make some economical calculus to see which one is cheaper. (Chiadamrong, O'Brien, 1999)

The costs for Abrasive Water Jet Cutting per hour ([euro]/h) considering the water pressure P and nozzle diameter do are presented in table 1. In this case study water pressure value was 300 MPa and the diameter of the nozzle was 0.4 mm therefore the cost of manufacturing is 48.7 ([euro]/h).

[FIGURE 4 OMITTED]

[FIGURE 5 OMITTED]

3. RESULTS

If we consider the cost of 48.7 [euro] per hour and the estimated time to make this part (2.482 min), we obtain a cost of 2.01 [euro] per part. Also the machine program estimated a cost of 3.1 [euro] for each part.

Machining this product with alternative technologies such as water jet cutting process we managed to have a much smaller price for this product, from 42 [euro], as listed on Robot Market Place.

Manufacturing time using alternative technology is notably lower than the time for traditional manufacturing of the same part.

4. CONCLUSION

I consider that in the new era of virtual enterprises both technologies can be used in order to manufacture industrial products but alternative technologies can achieve a better time to market and lower costs for the manufactured products.

The link between the alternative technologies and virtual enterprises in this case study was represented by the geographical distribution of the different departments (CAD, CAM, CAE, manufacturing).

The communication between those departments was made with virtual enterprise specific technologies (INTERNET / INTRANET / EXTRANET) through a portal.

5. REFERENCES

Camarinha-Matos, L. M. (2002), Virtual organizations in manufacturing: Trends and challenges. FAIM 2002, 12th Int. Conf. On Flexible Automation and Intelligent Manufacturing, ISBN 3-486-27036-2, pp. 1036-1054, Germany, Jul 2002

Chiadamrong N., O'Brien C. (1999), Decision support tool for justifying alternative manufacturing and production control systems, International Journal of Production Economics, Volumes 60-61, Elsevier Ed., pp 177-186, ISSN 0925-5273, April 1999

Kramar D., Junkar M. (2003), The Development of a Software Tool for the Selection of Contour-Cutting Processes, Journal of Mechanical Engineering 49(2003)6, pp 346-365, ISSN 0039-2480

Parpala L.F., Popa C.L. (2007), Remodeling and validation by simulation of manufacturing systems architecture for the integration in virtual enterprise platforms, Annals of the

Oradea University, Fascicle of Management and technological engineering, Vol. VI (XVI), 2007, pp. 16101613, ISSN 1583-0691, Baile Felix, May 2007

*** (2006) http://www.robotmarketplace.com Accesed on: 2006-12-20

Tab. 1. Costs for Abrasive Water Jet Cutting ([euro]/h) considering
the water pressure and nozzle diameter (Kramar, Junkar, 2003)

[c.sub.e]--El. Energy      Initial cost               150.000 [[euro]]
  (cca. 0.12 [euro]/kWh)
[c.sub.w]--Water           Lifetime                           15.000 h
  (cca. 0.5 *
  [10-.sup.3][euro]/1)
[c.sub.a]--Nozzle          Maintenance costs         5.000 [euro]/year
  (cca. 40 [euro]/part)
[c.sub.e]--Mixing tube     Machine utilization   2.000 h/year
  (cca. 200 [euro]/part)   Water pressure P [MPa]

Nozzle diamter
[d.sub.o][mm]               200       250      300     350

0.2                        21.1      22.1     23.0    23.9
0.3                        29.4      31.6     33.7    35.7
0.4                        41.1      45.0     48.7    52.3
0.5                        56.1      62.1     67.9    73.5