A geometric algorithm for selecting optimal set of cutters for multi-part milling

ABSTRACT

For the manufacture of milled parts, it is well known that the size of the cutter significantly affects the machining time. However, for small-batch manufacturing, the time spent on loading tools into the tool magazine and establishing z-length compensation values is just as important. If we can select a set of milling tools that will produce good machining time on more than one type of parts, then several unnecessary machine-tool reconfiguration operations can be eliminated. This paper describes a geometric algorithm for finding an optimal set of cutters for machining a set of 2½D parts. In selecting milling cutters we consider both the tool loading time and the machining time and generate solutions that allow us to minimize the total machining time. Our problem formulation addresses the general problem of how to cover a target region to be milled with a cylindrical cutter without intersecting with the obstruction region; this definition allows us to handle both open and closed edges in the target region. Our algorithm improves upon previous work in the tool selection area in following ways: (1) in selecting cutters, it accounts for the tool loading time, and (2) it can simultaneously consider multiple different parts and select the optimal set of cutters to minimize the total manufacturing time.

REFERENCES

• 1: Sunil Arya , Siu-Wing Cheng , David M. Mount, Approximation algorithms for multiple-tool miling, Proceedings of the fourteenth annual symposium on Computational geometry, p.297-306, June 07-10, 1998, Minneapolis, Minnesota, United States [doi>10.1145/276884.276918]
• 2: M.Bala and T.C.Chang. Automatic cutter selection and optimal cutter-path generation for prismatic parts. International Journal of Production Research, 29(11), 2163- 2176, 1991.
• 3: Thomas T. Cormen , Charles E. Leiserson , Ronald L. Rivest, Introduction to algorithms, MIT Press, Cambridge, MA, 1990
• 4: Christoph M. Hoffmann, Geometric and solid modeling: an introduction, Morgan Kaufmann Publishers Inc., San Francisco, CA, 1989
• 5: Y.S. Lee, B. K. Choi and T. C. Chang. Cut distribution and cutter selection for sculptured surface cavity machining. International Journal of Production Research 30(6), 1447- 1470, 1993.
• 6: K. Lee, T. J. Kim and S. E. Hong. Generation of toolpath with selection of proper tools for rough cutting process. Computer-Aided Design, vo1(26) 822-831, Nov. 1994.
• 7: Yuan-Shin Lee , Tien-Chien Chang, Application of computational geometry in optimizing 2.5D and 3D NC surface machining, Computers in Industry, v.26 n.1, p.41-59, April 1995 [doi>10.1016/0166-3615(95)80005-0]
• 8: Y.S. Lee and T. C. Chang. Automatic cutter selection for 5- axis sculptured surface machining. International Journal of Production Research, 34(4), 977-998, 1996.
• 9: T.Lim, J.Comey, J.M.Ritchie and D.E.R.Clark, Optimising automatic tool selection for 21/2D components. In Proc. DETC 2000:2000 ASME Design Engineering Technical Conference, Baltimore, MD, September 10-13, 2000.
• 10: T.Lim, J.Comey and D.E.R.Clark. Exact tool sizing for feature accessibility. International Journal of Advanced Manufacturing Technology, Vol. 16, pp.791-802, 2000
• 11: B. Mahadevan, L. Putta and S. Sarma. A feature free approach to tool selection and path planning in 3-axis rough cutting. Proceedings of First International Conference on Responsive Manufacturing, Nottingham, pp.47-60, September 1997.
• 12: Ganping Sun, Fu-Chung Wang, Paul Wright and Carlo Sequin. Operation decomposition for freeform surface features in process planning. In Proc. DETC 1999:1999 ASME Design Engineering Technical Conference, Las Vegas, Nevada, September 12-15, 1999.
• 13: D. Veeramani, and, Y. S. Gau. Selection of an optimal set of cutting-tool sizes for 2.5D pocket machining. Computer- Aided Design, 29(12), 869-877, 1997.
• 14: D.C.H. Yang and Z. Han. Interference detection and optimal tool selection in 3-axis NC machining of free-form surface. Computer-Aided Design, Vol.31, pp.303-315, 1999.
• 15: Zhiyang Yao, S. K. Gupta and Dana Nan. A Geometric Algorithm for Finding the Largest Milling Cutter. SME's Journal of Manufacturing Processes. To appear, 2001.

INDEX TERMS

Primary Classification:
  I. Computing Methodologies
  I.3 COMPUTER GRAPHICS
      I.3.5 Computational Geometry and Object Modeling
          Subjects: Geometric algorithms, languages, and systems

Additional Classification:
  J. Computer Applications
  J.2 PHYSICAL SCIENCES AND ENGINEERING
      Subjects: Engineering

General Terms:
Algorithms, Design, Measurement, Performance, Theory, Verification

Keywords:
computer-aided process planning, milling cutter selection