owner, operators are given greater responsibility, i.e.: changing wear offsets, performing setups and minor program editing. The first and second chapters emphasize the development of machine setup and program editing skills. Students, machinists, supervisors and design and manufacturing engineers will benefit from these chapters by learning foundational skills associated with setup and operation of CNC machine tools, prior to programming.
Chapters three and four focus on the components and development of program code for CNC Turning and Machining Centers, with over 50 programming examples.
Because of the common use of Computer Aided Design and Computer Aided Manufacturing (CAD/CAM) today and the increasing popularity of Conversational Programming at the machine controller, two new chapters were added to the second edition. In this third edition, the CAD/CAM chapter has been updated to include the current version Mastercam X2 software. Additionally, a new chapter has been added for “Computer Aided Manufacturing from Solid Models” where the latest version of EdgeCAM by Pathtrace is featured. Because of the effectiveness of CAD/CAM, it is now the conventional method for programming used today.
The Mazatrol Conversational Programming chapter has been expanded to include programming examples and study questions and an example program is created using MazaCAM off-line programming software by SolutionWare. Many new machine tools come standard with some form of Conversational Programming.
The appendix contains many useful charts, techniques and math formulas used for line-by-line programming for user reference and the glossary of terms has been expanded to include more definitions.
The purpose of this book is to expand the reader’s current knowledge of CNC programming by providing full descriptions of all program functions and their practical applications. The book contains information on how to program turning and milling machines, which is applicable to almost all control systems. In order to provide clear explanations about one unified system, the controller model referenced here is one of the most widely accepted, popular numerical control systems used worldwide.
Third Edition by Ken Evans
1.Recognize the importance of Safety when working with CNC Machines.
2.Become familiar with Tool and Work holding methods for CNC Machining.
3.Learn how to calculate proper Feeds and Speeds for CNC Machining.
4.Learn how to plan for CNC programming by using Process Planning Documents.
5.Become familiar with Coordinate Systems and their use in CNC Programming
6.Learn terminology and acronyms associated with the CNC Basics.
7.To learn the ABC’s of CNC program format.
As you begin to learn about CNC Programming, it is important to first become aware of and learn how to practice safe working habits. You should not operate any machine without first understanding the basic safety procedures necessary to protect yourself and others from injury, and the equipment from damage. Most CNC machines are provided with a number of safety devices (door interlocks, etc.), to protect personnel and equipment from injury or damage. However, operators should not rely solely on these safety devices, but should operate the machine only after reading and fully understanding the Safety Precautions and Basic Operating Procedures outlined in the maintenance and operation manuals provided with the equipment. The following are some Do’s and Don’ts that should be practiced when working with CNC Machines.
Safety Rules for NC and CNC Machines
Do’s:
•Wear safety glasses and safety shoes at all times.
•Know how to stop the machine under emergency conditions.
•Keep the surrounding area well lighted, dry and free from obstructions.
•Keep hands out of the path of moving parts during machining operations.
•All setup procedures and loading or unloading of workpieces must be performed with the spindle stopped.
•Follow recommended safety policies and procedures when operating machinery, handling parts or tooling, and when lifting.
•Machine guards should be in position during operation.
•Wrenches, tools and parts should be kept away from the machine’s moving parts.
•Make sure fixtures and workpieces are securely clamped before starting the machine.
•Cutting tools should be inspected for wear or damage prior to use.
Don’ts:
•Never operate a machine until properly instructed in its use.
•Never wear neckties, loose fitting long sleeves, wristwatches, rings, gloves or unrestrained long hair, when operating any machine.
•Never attempt to remove metal chips with hands or fingers.
•Never direct compressed air at yourself or others.
•Never operate an NC/CNC machine without first consulting the specific operator manual for the machine.
•Never place hands near a revolving spindle.
•Electrical cabinet doors are to be opened only by qualified personnel for maintenance purposes.
A large investment has been made to purchase CNC equipment. It is very important to recognize the need for proper maintenance and a general upkeep of these machines. At the beginning of each opportunity to work on any Turning or Machining Center, verify that all lubrication reservoirs are properly filled with the correct oils. The recommended oils are listed in the operation or maintenance manuals typically provided with the equipment. Sometimes there is a placard (plate) with a diagram of the machine and numbered locations for lubrication and the oil type is found on the machine. Most modern CNC machines have sensors that will not allow operation of the machine when the Way or Spindle oil levels are too low. Pneumatic (air) pressures need to be at a specified level and regulated properly. If the pressure is too low, some machine functions will not operate until the pressure is restored to normal. The standard air pressure setting is listed in Pounds per Square Inch (PSI) and a pressure regulator is commonly located at the rear of the machine. Refer to the operator or maintenance manuals for recommended maintenance activities.
Coolant Reservoir
The Coolant tank level should be checked and adjusted as needed prior to use. A site glass is normally mounted on the tank for easy viewing. Use an acceptable water-soluble coolant mix, synthetic coolant or cutting oil. Periodically
