Copyright Goodheart-Willcox Co., Inc. 208 Summary ■ The process of program planning should include a thorough print review, consideration for workholding, and tools needed to complete the process. It is best practice to take a team approach to part manufacturing. ■ Special review of workholding should be considered to maximize machining and minimize setups and operations. ■ A CNC mill program consists of an opening statement, body, and closing statement. ■ G codes are called preparatory commands and place the machine in a specific mode or state of operation. ■ M codes are called miscellaneous functions and serve as “switches” to turn on and off specific machine functions. ■ A pocketing toolpath is used when a large volume of material needs to be removed on the internal boundaries of a part. ■ The contour toolpath is used when following a single line of geometry or one specific path. ■ Canned cycles allow a single line of code to define multiple parameters. They reduce programming time and programmer errors. ■ The use of cutter compensation offsets the tool around the finished geometry by an amount stated in the controller. This allows for programming to part dimensions and making minor adjustments to offset cut dimensions. ■ The G02 and G03 commands create an arc movement with the tool. The G02 creates a clockwise arc, and the G03 creates a counterclockwise arc. ■ An angle movement is created by using two axis locations on the same line of the program. This can be used with any combination of axes that are available on the machine. ■ When entering into material with a cutter, an angled or helical move should be used. Direct plunging into material can cause a tool failure or part damage. Chapter Review Review Questions Answer the following questions using the information provided in this chapter. Know and Understand 1. Try to minimize the number of tools you use to reduce _____ and _____. A. tool changes, setup work B. tool changes, cycle time C. errors, offset changes D. canned cycles, work offsets 2. What are the three sections of a CNC program? A. Beginning, middle, end B. Starting, body, end C. Opening statement, tool statement, closing argument D. Opening statement, body, closing statement 3. True or False? Each program number will be preceded by the letter “O.” 4. The program address G is commonly referred to as the _____. A. preparatory command B. address code C. opening statement D. rapid movement 5. The G code command for a straight-line feed move is the _____. A. G03 B. G00 C. G01 D. G72 6. True or False? One of the G code designators for work coordinate systems is G73. 7. The program address M is commonly referred to as a _____. A. machine function B. miscellaneous function C. multiple function D. multiple fraction