CNC Circular Interpolation

How to use Circular Interpolation in CNC programming. Making easy to understand and apply.

1. CNC Mc Programming Circular Interpolation G02 / G03 Presentation By: 22 Century Technologies Sandeep Adkar B.E. (Mech.), M.B.A. (Marketing) Ex Plant Manager / GM – Operations, Cummins Turbo E mail: [email protected] Web: ww w.22centech.com Field: Automobile production, CNC Machining & Programming 22 Century Technologies, Mfg Skill Develop, [email protected], www.22centech.com 1

2. Circular Interpolation Circular Interpolation G02, G03 Modal Circular interpolation commands G02, G03 are used to cut circles or circular arcs. G02 & G03 define clockwise and counter clockwise motion respectively. G02-Clockwise G03-Counterclockwise ( CW) ( CCW) Plane selection 12 9 6 3 12 9 6 3 22 Century Technologies, Mfg Skill Develop, [email protected], www.22centech.com 2

3. Circular Interpolation Format: Plane Selection + CW or CCW + End Point of Arc Cutting + Arc/Radius Centre + Cutting Feed Rate ; G17 / G18 / G19 G02 / G03 X_ Y_ / X_ Z_ / Y_ Z_ R / I_ J_ / I_ K_ / J_ K_ F_ _; + + + + 22 Century Technologies, Mfg Skill Develop, [email protected], www.22centech.com 3

4. Circular Interpolation The interpolation parameters together with axis commands determine the circle or arc. SP: Start point is determined by previous block EP: End point is determined by the axis values in resp plane. CP: Circle center point is determined by I, J and K. EP SP CP -I -J +R +X +Y -X -Y A + I +J 22 Century Technologies, Mfg Skill Develop, [email protected], www.22centech.com 4

5. Circular Interpolation G02 G03 G02 G02 G03 G03 Y, 2 nd axis Z, 3 rd axis X, 1 st axis Plane selection is must for circular interpolation. Dimensions I, J and K: Command I and J specify the perpendicular distances from the start point SP of circular arc A to the center point CP. I, J & K must be specified incrementally whether under ABS or INC mode , adding + or – sign for the direction of I, J, K. If an interpolation parameter is not programmed, zero is automatically generated by the control. I : parallel to X axis J : parallel to Y axis K : parallel to Z axis 22 Century Technologies, Mfg Skill Develop, [email protected], www.22centech.com 5

6. Circular Interpolation Circle center point is defined either through sign dependent vectors I, J & K, from a range of 0 to 360 degree. The sign results from the coordinate direction from the start point to the center point . Or directly through the radius R, R + angle for less than or equal to 180 deg . R - angle for greater than 180 deg . R must have negative sign. This is how the machine differentiates when there are two possibilities. The direction in which the arc is traversed is determined by G02 or G03. Circular interpolation is possible in 2 out of 4 axes, both not parallel. Radii must not be programmed when the angle to be traversed is 0 deg or 360 deg. In such cases the full circles must be programmed using the interpolation parameter I, J and K . 22 Century Technologies, Mfg Skill Develop, [email protected], www.22centech.com 6

7. Circular Interpolation Eg.1: Movement in circular interpolation using interpolation parameters I, J and K. 60 10 30 30 +Y +X A B I=0 J=20 Arc center (X60, Y30) An arc from A and B in both directions. Under ABS mode: N5 G17 G02 G90 X30.0 Y30.0 I0 J20.0; Tool moves from A to B Justification: Here X coordinate is same for both start point and arc center. Y coordinates are +20mm apart, starting from arc start point to arc center, in +Y direction. So I=0 and J=+20 . N6 G17 G03 G90 X60.0 Y10.0 I30.0 J0; Tool moves from B to A 22 Century Technologies, Mfg Skill Develop, [email protected], www.22centech.com 7

8. Circular Interpolation Eg.1: Movement in circular interpolation using interpolation parameters I, J and K. An arc from A and B in both directions. Under INC mode: N5 G17 G02 G91 X-30.0 Y20.0 I0 J20.0; Tool moves from A to B Justification: Here X coordinate is same for both start point and arc center. Y coordinates are +20mm apart, starting from arc start point to arc center, in +Y direction. So I=0 and J=+20 . N6 G17 G03 G91 X30.0 Y-20.0 I30.0 J0; Tool moves from B to A 60 10 30 30 +Y +X A B I=0 J=20 Arc center (X60, Y30) 22 Century Technologies, Mfg Skill Develop, [email protected], www.22centech.com 8

9. Circular Interpolation Eg . 2 : Movement in circular interpolation using interpolation parameters I, J and K. 20 50 10 20 10 50 +Y +X J=-10 I=-40 B (End of circular arc) A (Start of circular arc) C An arc from A and B in both directions. Under ABS mode: N3 G17 G90 G03 X20.0 Y50.0 I-40.0 J-10.0 F100; Tool A to B Distance from point A (start of arc) to the center of arc C with sign. N4 G17 G90 G02 X50.0 Y20.0 I-10.0 J-40.0 F100; Tool B to A Distance from point B (start of arc) to the center of arc C with sign. 22 Century Technologies, Mfg Skill Develop, [email protected], www.22centech.com 9

10. Circular Interpolation Eg . 2 : Movement in circular interpolation using interpolation parameters I, J and K. An arc from A and B in both directions. Under INC mode: N4 G17 G91 G03 X-30.0 Y30.0 I-40.0 J-10.0 F100; Tool A to B Distance from point A (start of arc) to the center of arc with sign. N5 G17 G91 G02 X30.0 Y-30.0 I-10.0 J-40.0 F100; Tool B to A Distance from point B (start of arc) to the center of arc with sign. 20 50 10 20 10 50 +Y +X J=-10 I=-40 B (End of circular arc) A (Start of circular arc) C 22 Century Technologies, Mfg Skill Develop, [email protected], www.22centech.com 10

11. Circular Interpolation Circular Interpolation by Specifying Radius of Circular Arc, R: The starting point of the circle or arc is determined by the previous block. The end point is given by both of the axis values (e.g. X and Y). The circle center is defined by the signed radius. The radius of circular arc can be directly specified by R instead of specifying the center of circular arc by I, J and K. The sign of the radius value is given according to the size of the traversing angle, Radius less than or equal to 180 R+A R+30 Radius greater than 180 R-B R-60 No radii may be programmed, when the distance between the circle start point and circle end point is less than or equal to 10 µ m. That means a complete circle must be programmed using the interpolation parameters I, J and K . 22 Century Technologies, Mfg Skill Develop, [email protected], www.22centech.com 11

12. Circular Interpolation Eg . 3 : Movement in circular interpolation by specifying the radius . 60 15 45 30 +Y +X A B Arc center (X60, Y45) R30 An arc from A and B in both directions. Under ABS mode, N05 G17 G03 G90 X60.0 Y15.0 R30.0; Tool moves from B to A N15 G17 G02 G90 X30.0 Y45.0 R30.0; Tool moves from A to B Under INC mode, N05 G17 G03 G91 X30.0 Y-30.0 R30.0; Tool moves from B to A N15 G17 G02 G91 X-30.0 Y30.0 R30.0; Tool moves from A to B 22 Century Technologies, Mfg Skill Develop, [email protected], www.22centech.com 12

13. Circular Interpolation Eg . 4: Movement in circular interpolation along an arc from A and B in both directions with angle >180 . 20 60 20 60 +Y +X B A End Start R40 180 or more An arc from A to B in clockwise direction. Under ABS mode: G17 G90 G02 X60.0 Y20.0 R-40.0 F100; A to B G17 G90 G03 X20.0 Y60.0 R-40.0 F100; B to A Under INC mode: G17 G91 G02 X40.0 Y-40.0 R-40.0 F100; A to B G17 G91 G03 X-40.0 Y40.0 R-40.0 F100; B to A When the control range of arc is 180 deg or more, the radius R must be specified with negative (-) sign. 22 Century Technologies, Mfg Skill Develop, [email protected], www.22centech.com 13

14. Circular Interpolation A Complete Circle- Complete circle can be programmed by using one block with I, J & K. +Y +X B A R40 A complete circle from point A in clockwise direction, ABS – G17 G90 G02 (X0.0 Y40.0) I0 J-40.0 F100; INC – G17 G91 G02 (X0.0 Y0.0) I0 J-40.0 F100; A complete circle from B in clockwise direction, ABS – G17 G90 G02 (X40.0 Y0.0) I-40.0 J0 F100; INC – G17 G91 G02 (X0.0 Y0.0) I-40.0 J0 F100; 22 Century Technologies, Mfg Skill Develop, [email protected], www.22centech.com 14

15. Circular Interpolation +Y +X B A R40 Command in () can be omitted. They are written for easy understanding. The arc radius R programming is not available to a complete circle and only I, J and K are used. If I, J, K and R are specified in the same block R has the priority and I, J & K are ignored. Since the start point and end point are at the same location, it is not necessary to indicate X and Y coordinate. 22 Century Technologies, Mfg Skill Develop, [email protected], www.22centech.com 15

16. Circular Interpolation Eg . 5: Start from the zero point, turn clockwise and return to zero. The cutting feed rate for straight line is F200 and for arc is F50. P2 (X20, Y0) P1 (X20, Y30) P4 (X-30, Y0) P3 (X0, Y-20) P5 (X0, Y30) --- - Cutting feed Rapid traverse O0010; N1 G90 G54 G17 G00 X20.0 Y30.0 S1000 M03; ( 0-1) N2 G01 (X20.0) Y0.0 F200; ( 1-2) N3 G02 X0.0 Y-20.0 R20.0 F50.0; (Put R= I-20.0 J0) ( 2-3) N4 G01 X-30.0 Y0.0 F200.0; ( 3-4) N5 G02 X0.0 Y30.0 R30.0 F50.0; (Put R= I30.0 J0) (4-5) N6 G01 X20.0 (Y30.0) F200.0; ( 5-1) N7 G00 X0.0 Y0.0; ( 1-0) N8 M30 ; ( Commands in bracket can be omitted .) 22 Century Technologies, Mfg Skill Develop, [email protected], www.22centech.com 16

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