1. Metric and Imperial Programming CNC lathes typically use either metric or imperial units for length measurements, depending on the system settings. These units are set using specific command codes. For example, in the FANUC-0TC system, G20 is used to switch to imperial units, while G21 activates metric units. Upon startup, the machine defaults to metric units by default, ensuring consistency in most modern manufacturing environments. 2. Diameter and Radius Programming (1) Diameter programming involves using the X-axis coordinate value as the diameter of the part. This method is commonly used because it simplifies programming and reduces the chances of errors. (2) In radius programming, the X-axis coordinate represents the radius of the part. While this can also be effective, diameter programming is more widely adopted due to its ease of use. Most CNC systems default to diameter programming unless otherwise specified. a) Diameter programming b) Radius programming Figure 1 CNC Turning Programming Classification 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 The tool post layout in CNC lathes comes in two main configurations, as shown in Figure 2. Figure 2 Front Tool Post and Rear Tool Post (1) Front tool post: Positioned in front of the Z-axis, this layout resembles traditional horizontal lathes. It uses a horizontal tool slide and a four-position turret. (2) Rear tool post: Located behind the Z-axis, this design allows better visibility of the cutting process and easier chip removal. It provides more space for additional tools, making it ideal for multi-functional CNC lathes. 4. Tool Nose Radius Compensation In CNC turning programming, the tool tip is often assumed to be a sharp point for simplicity. However, in reality, the tool has a rounded nose with a specific radius. To ensure accurate machining, the CNC system compensates for this radius. Fig. 3 Imaginary Nose and Nose Radius When programming, the known tool nose radius is entered into the compensation table. During execution, the system automatically adjusts the tool path to account for the actual radius. This ensures that the final part meets the required dimensions. Indexable inserts are commonly used in CNC machining, and each insert has a fixed nose radius. Choosing the right insert type determines the appropriate radius for the tool. Tool nose radius compensation commands include: - G41: Left-side tool nose radius compensation - G42: Right-side tool nose radius compensation - G40: Cancels the tool nose radius compensation These commands must be applied during linear movements to ensure proper function. The direction of the tool movement determines whether left or right compensation is used. 5. Initial State of CNC Machine Tools The initial state of a CNC machine refers to the default configuration after power-up. This includes absolute coordinate mode, metric units, no tool compensation, and the spindle and coolant pump turned off. This setup ensures a safe and predictable starting point for any machining operation. Understanding these defaults is essential for setting up and running CNC programs effectively. Full Closed Cabin Scooter,Full Colosed Tricycle,Full Closed Scooter,Cabin Scooter YUMBOMOBILITY LTD , https://www.yumbomobility.com
