Chapters 21, 22, and 23 cover a lot. Chapter 21 covers the following: defining numerical control, describing the difference between incremental and absolute positioning methods, explaining the operation of numerical control (NC), direct and/or distributed numerical control (DNC) and computer numerical control (CNC). work and how computer-aided programming and manual programming are carried out. Chapter 22 covers the definition of the term "industrial robot", the term "automation", describing several automated production systems (APS), and discussing the use of robotics in APS. Chapter 23 covers the need for quality control, the difference between the two basic quality control techniques, how nondestructive testing works, and methods for ensuring quality control during and after machining. In Chapter 21, the material covered is numerical control, positioning methods, how numerical control (NC), direct and distributed numerical control (DNC) and computer numerical control (CNC) work, and how programming works computer and manual. “Numerical control is not a machining process, but the operation of the machine tool through a series of coded instructions” (Walker, 2004, p. 399). The NC instructions contain so-called alphanumeric data which is transformed into electric current and can then activate the servo motors. They are connected to the machine power supply and to the lead screws which provide the energy necessary for the cutter. The instructions tell the servos when to start, where they should move, and how far they should move. The same program controls feed rate, cutting speed, coolant flow and sometimes even tool changes. CN morphed into CNC and are both a form of DNC. The CNC is what is used...... middle of paper ......st for part defects. Laser inspection is another method, the laser detects tool wear and attempts to compensate for it. This is an effort to prevent imperfections in certain parts from occurring. Eddy current inspection is based on the fact that resistance in the coils is caused by imperfections in the part. There are various eddy current tests that facilitate the inspection and completion of the part and maintain the quality control effort. As presented, chapters 21, 22 and 23 provide a lot of information. Chapter 21 concerns numerical controls and the operation of NC, DNC and CNC. Chapter 22 is about robots and how they work in industry. Chapter 23 covers the importance of quality control and the different ways to achieve it. ReferencesWalker, J. (2004). Fundamentals of machining. Tinley Park, IL: The Goodheart-Willcox Company, Inc..