1. what are machine-tools used for? 2 ow are most machine-tools driven nowadays? 3. what facilities have all machine-tools? 4. how are the cutting tool and the workpiece cooled during machining? oped lately? of a range of products without the use of manual labour? 5. what other machining methods have been devel- кру 6. what systems are used now for the manufacture tok 7. what parts can be made with lathes? 8. how can the cutting tool be moved on a lathe? 9. how is the workpiece clamped in a lathe? 10. can we change the speeds of workpiece rotation in a lathe? 11. what is numerical control of machine tools used for?

1. Machine-tools are used for various operations in manufacturing or shaping materials. These operations include cutting, drilling, shaping, grinding, and more. Machine-tools are essential in the production of different products, such as cars, furniture, electronics, and appliances.

2. Nowadays, most machine-tools are driven by various power sources, including electricity, hydraulics, or pneumatics. Electric motors are the most common source of power for machine-tools. They provide the necessary rotational force to drive the cutting tools or move the workpiece.

3. All machine-tools have certain facilities to ensure their proper functioning and efficiency. These facilities include a power source, a control system, a working platform or bed, cutting or shaping tools, and coolant systems. The power source provides the necessary energy to drive the machine, the control system enables operators to give commands and adjust settings, the working platform provides stability for the workpiece, and coolant systems help in cooling the cutting tools and workpiece during machining.

4. During the machining process, cutting tools and workpieces are cooled to prevent overheating and to prolong tool life. This is done by using coolant systems, such as a stream of coolant liquid or air. Coolant systems help dissipate heat generated during machining, lubricate the cutting tool, and remove chips or debris from the cutting zone.

5. Apart from traditional machining methods like cutting and shaping, various other methods have been developed. These methods include electrochemical machining, ultrasonic machining, laser machining, and abrasive jet machining. Each of these methods has its specific advantages and applications in different industries.

6. In recent years, computer numerical control (CNC) systems have been widely used for the manufacture of a range of products without the use of manual labor. CNC systems are computer-based controls that automate the production process, allowing for precise and repeatable machining operations. These systems use programmed instructions to control machine movements, tool paths, and parameters.

7. Lathes are versatile machine-tools used for shaping cylindrical or round parts. With lathes, various parts can be made, such as shafts, bolts, screws, wheels, and more. Lathes allow for operations like turning, facing, threading, and drilling on the workpiece.

8. The cutting tool on a lathe can be moved in different ways. It can be manually moved by the operator using handwheels or levers. Alternatively, automated movements can be achieved using power-driven slides or computer numerical control (CNC) systems. These movements control the depth of cut, feed rate, and direction of the cutting tool.

9. In a lathe, the workpiece is clamped securely to prevent any movement during machining. This is usually done using a chuck or a collet. The chuck is a holding device that grips the workpiece tightly, allowing it to rotate concentrically with the lathe spindle. In some cases, additional support may be provided using a center or steady rest.

10. Yes, the speeds of workpiece rotation in a lathe can be changed. Lathes often have a variable speed mechanism that allows operators to adjust the rotation speed according to the requirements of the machining operation. This feature is crucial when different materials or operations demand specific cutting speeds.

11. Numerical control of machine tools, often referred to as CNC, is a technology used to automate the control and operation of machine tools. It involves using computer programming to control the movements and functions of the machine. CNC systems allow for precise and complex machining operations by providing accurate control over the cutting tool's movement, speed, and position. This technology enables efficient production, increased productivity, and improved accuracy in manufacturing processes.