1. Metric and Imperial Programming CNC lathes typically use either metric or imperial units for programming. The unit of length is specified using a dedicated command. For example, in the FANUC-0TC system, G20 sets the machine to imperial units, while G21 activates metric units. Upon startup, most CNC systems default to metric units, ensuring consistency in machining operations. 2. Diameter and Radius Programming (1) Diameter programming: In this method, the X-axis coordinate values in the NC program represent the diameter of the part, as shown on the drawing. (2) Radius programming: Here, the X-axis coordinates are based on the radius of the part. While both methods are valid, diameter programming is more commonly used due to its simplicity and ease of interpretation. Most CNC systems default to diameter programming for convenience. a) Diameter programming b) Radius programming Figure 1: Classification of CNC Turning Programming a) A: (30.0, 80.0), B: (40.0, 60.0) b) A: (15.0, 80.0), B: (20.0, 60.0) 3. Front Tool Post and Rear Tool Post CNC lathes can be equipped with either front or rear tool posts, each with different layouts. As shown in Figure 2: Figure 2: Front and Rear Tool Posts on a Lathe (1) Front tool post: Positioned in front of the Z-axis, it follows the traditional layout of horizontal lathes, featuring a horizontal guide rail and a four-station turret. (2) Rear tool post: Located behind the Z-axis, it has an inclined guide rail that allows better visibility during cutting, easier chip removal, and more space for additional tools. This design is common in multi-functional CNC lathes. 4. Tool Nose Radius Compensation In CNC turning, the tool tip is often assumed to be a sharp point for easier programming. However, real-world cutting tools have a rounded nose. To account for this, the CNC system uses tool nose radius compensation. Fig. 3: Imaginary Nose and Nose Radius The tool nose radius is entered into the tool compensation table. During operation, the CNC system automatically adjusts the tool path to account for the actual radius of the cutting edge. Indexable inserts are commonly used in CNC machining, and their nose radii are fixed. Choosing the right insert type helps ensure accurate machining results. Tool nose radius compensation commands include: These commands must be used with linear motion (G01) to activate or deactivate the compensation. The direction of the tool movement determines whether G41 or G42 is applied. 5. Initial State of CNC Machine Tools Upon power-up, the CNC machine enters its initial state, also known as the default configuration. This typically includes absolute coordinate mode, metric units, no tool compensation, and the spindle and coolant pump turned off. This setup ensures a safe and consistent starting point for all machining operations. Three Seats Electric Car,Electric Tricycle For Elderly,Low Speed Car,Electric Vehicles YUMBOMOBILITY LTD , https://www.yumbomobility.com
