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From Peter Smid, CNC Programming Handbook: A Comprehensive Guide to Practical CNC Programming, Second Edition, Industrial Press, Inc. 200 Madison Avenue, New York, 2003. CHAPTER 6: PROGRAMMING PLANNING The development of any CNC program begins with a very carefully planned process. Such a process starts with the engineering drawing of the required part. Before the part is machined, several steps have to considered and carefully evaluated. The more effort is put into the planning stage of the program, the better results may be expected at the end. STEPS IN PROGRAM PLANNING The steps required in program planning are decided by the nature of the work. There is no formula for all the jobs, but some basic steps should be considered: * Initial information / Machine tools features * Part complexity * Manual programming / computerized programming * Typical programming procedure * Part drawing / Engineering data * Methods sheet / Materials specifications * Machining sequence * Tooling selection * Part setup * Technological decisions * Work sketch and calculations * Quality considerations in CNC programming The steps in the list are suggestions only a guideline. They are quite flexible and should always be adapted for each job and to the specific conditions of the work. INITIAL INFORMATION Most drawings define only the shape and size of the completed part and normally do not specify data about the initial blank material. For programming, a good knowledge of the material is an essential start - mainly in terms of its size, type, shape, condition, hardness, etc. The drawing and material data are the primary information about the part. At this point, CNC program can be planned. The objective of such a plan is to use the initial information and establish the most efficient method of machining, with all related consideration – mainly part accuracy, productivity, safety and convenience. The initial part information is not limited to the drawing and the material data, it also inclu