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Ch56-I044963.fm Page 277 Thursday, July 27, 2006 8:22 AM
Thursday, July 27, 2006
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Ch56-I044963.fm
8:22 AM
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A ROBOTIZED SYSTEM FOR PROTOTYPE MANUFACTURING
OF CASTINGS AND BILLETS

1
Mikko Sallinen , Matti Sirvio 2
'VTT Electronics, Kaitovayla 1, 90571 Oulu, Finland
Simtech Systems Inc.oy, Kukkaromaki 6C5, 02770, Espoo, Finland

ABSTRACT

In this paper, we present a new method for manufacturing prototype castings using robot-based
system. The contribution of the paper is new methods and tools for managing very different sizes of
work pieces. The tools helps and assists the designer for manufacturing pieces which are not a
straightforward to program for the robot. The methods are designed for prototype manufacturing
which means lotsize is something between one to ten.

KEYWORDS: robot milling, off-line programming, prototype casting

1. INTRODUCTION
The models for prototypes of the cast objects has been traditionally made by hands. They are made
by wood and the form has been generated into a sand box. Nowadays, the wooden or plastic models
are made using a milling machine where the first step towards automation has been taken. However,
the disadvantages of the milling machine is the price and flexibility and therefore we have been
taken a new approach to use robot as a milling machine Sirvio et. al. (2002). Robot-based milling
stations have been developed in low intensity over the last number of years. The two main
restrictive reasons for use of robot in milling are the rigidity of industrial robots and the difficulty of
flexible off-line programming. Rigidity of the robot systems is not anymore such a problem like
several years ago. However, in the last years, another problem has been high (or high enough)
absolute accuracy of the robot manipulators.

The machining of moulds or other prototypes has been made so far using a milling machine
Boomenthal (2000). The difficulty of programming 5-axis machining as well as the lack of required
accuracy has been forced to use three to five times expensive milling machine instead of a robot.
The robotic milling that has been done so far has been concentrated on milling on soft materials like
different kind of foams or wood to avoid the problems of rigidity Veergest et. al. (1998). The
machining of large work pieces and path planning for material removing has been studied in Jager
et. al. (2001).