179 Chap t er Ou t line 9.1 Introduction to CNC Mill Programming 9.2 Program Planning 9.2.1 Print Review 9.2.2 Part Workholding 9.2.3 Tool Selection 9.3 Program Format 9.3.1 Opening Statement 9.3.2 Program Body 9.3.3 Closing Statement 9.4 Address Codes 9.4.1 G Codes 9.4.2 M Codes 9.5 Contouring 9.5.1 Tool Start Position 9.5.2 Cutter Compensation 9.6 Radius and Angle Milling 9.6.1 G02 and G03 Radial Movements 9.6.2 I, J, and K Method 9.6.3 Programming Angles 9.7 Pocketing 9.7.1 Cutter Entry 9.7.2 Roughing Method 9.8 Canned Cycles 9.8.1 G83 Cycle (Full Retract Peck Drilling) 9.8.2 G73 Cycle (Chip Break Peck Drilling) 9.8.3 G81 Cycle (Spot Drilling) 9.8.4 G82 Cycle (Counterbore Cycle) 9.8.5 G84 Cycle (Tapping Cycle) 9.8.6 G85 Cycle (Fine Boring Cycle) 9.8.7 G86 Cycle (Spindle Stop Boring Cycle) 9.9 Tool Setting 9.9.1 Length Offsets 9.9.2 Diameter Offsets 9.10 Work Coordinate Offsets 9.10.1 Finding WCS on Material 9.10.2 Setting WCS on Control Learning Objec tives After reading this chapter, you should be able to: ■ Describe the process of program planning. ■ Explain how workholding affects programming. ■ Define the three parts of a CNC mill program. ■ Explain the use of G codes. ■ Describe when to use an M code. ■ Specify when a pocketing toolpath would be used. ■ Explain the contour toolpath. ■ Describe the benefits of canned cycles. ■ Explain the use of cutter compensation. ■ Use a G02 and G03 arc command. ■ Program angle moves. ■ Describe at least two different tool entry techniques. ■ Enter tool offsets on the appropriate offset page. Key Terms address code arc body canned cycle closing statement contouring cutter compensation default block design intent diameter offset hard tool I, J, and K method incremental position machine function (M code) machine home modal command opening statement peck drilling pocket milling preparatory command (G code) threads per inch (TPI) tool offset work coordinate system (WCS) workholding zero return