1. Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy McMaster University, Canada 57 th CIRP General Assembly, Dresden August 21, 2007

2. 2/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 Flushing of the interelectrode gap is of critical importance in EDM processes, in regard to machining productivity and machined surface quality

3. 3/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 Several techniques can be used to facilitate flushing in EDM through-tool forced flow jump EDM jet flushing horizontal EDM

4. 4/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 Another approach to flushing is to induce a relative motion between the electrodes ED-milling planetary EDM

5. 5/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 The present work involves kinematic aspects of rotating curvilinear tools for sinking cavities with sharp corners rotating sharpcorners tools curvilinear

6. 6/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 Reuleaux Triangle s 1 23

7. 7/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 Reuleaux Triangle is a curve of constant width that can rotate inside a square s s

8. 8/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 Kinematics of a Reuleaux Triangle

9. 9/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 For every revolution of the Reuleaux Triangle, the centroid traverses the orbit three times in the opposite direction The swept area is 98.8% of that of the square

10. 10/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 The area of a Reuleaux Triangle is 70.5% of that of the square A circular tool for machining a similar corner will only be 4% of the area of the square

11. 11/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 Replacing the complex orbit with a circular one facilitates implementation on a machine tool with a single servo-controlled axis, and entails a maximum profile deviation of only 0.003s

12. 12/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 Reuleaux Triangle tools correspond to improved removal rates and better surface quality Stationary RT 25 mm

13. 13/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 Machining of a square with a sharp corner using Reuleaux Triangle tools involves modifications to tool shape and tool path k = 1.93 for an included angle of 90 degrees

14. 14/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 Modification to tool path Y 0.034 number of sides

15. 15/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 Machining of a square with a sharp corner Locus magnified 2X

16. 16/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 Extension of the concept to machine regular polygons

17. 17/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 Machining of a hexagon Locus magnified 2X

18. 18/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 Machining of a non-regular polygon Locus magnified 2X

19. 19/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 Machining of a triangle

20. 20/20 Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 Conclusions Innovative kinematic schemes motivated by the concept of Reuleaux Triangle for the seemingly impossible task of using rotating tools to sink polygonal shapes with sharp corners are presented Application of the technology enhances gap flushing while maximizing the frontal machining area Efforts are required to address tool wear issues resulting from the adverse geometric relative duty of Reuleaux Triangle tools The work represents a significant advance towards exploiting the capabilities of CNC ram EDM

21. Rotating Curvilinear Tools for EDM of Polygonal Shapes with Sharp Corners Y. Ziada, P. Koshy 57 th CIRP General Assembly Dresden, Germany, August 21, 2007 For more information please see: Y. Ziada, P. Koshy, Rotating curvilinear tools for EDM of polygonal shapes with sharp corners, Annals of CIRP 56 (2007) 221-224. or email: koshy@mcmaster.ca