Overview and characteristics of CNC machining

Overview of CNC machining

CNC technology originated from the needs of the aviation industry. In the late 1940s, a helicopter company in the United States proposed the initial idea of CNC machine tools. In 1952, the Massachusetts Institute of Technology developed a three-coordinate CNC milling machine. In the mid-1950s, this CNC milling machine has been used to process aircraft parts. In the 1960s, the CNC system and programming work became more and more mature and perfect, and the CNC machine tools have been used in various industrial sectors, but the aerospace industry has always been the largest user of the CNC machine tools. Some large aviation factories are equipped with hundreds of CNC machine tools, including mainly cutting machine tools. The CNC machining parts include the integral siding of the aircraft and the rockets , Girder, skin, frame, propeller and aircraft engine casing, shaft, disc, blade and mold cavity of the combustion chamber of liquid rocket engine, etc. In the early stage of the development of CNC machine tools, CNC machine tools with continuous trajectory, continuous trajectory control, also known as contour control, requires the tool to move relative to the parts according to the specified trajectory. Later and vigorously develop the point control CNC machine tools. Point control is when the tool moves from one point to another, as long as it accurately reaches the target regardless of the route.

Characteristics and benefits

At the beginning of the CNC machine tool, the aircraft parts with complex surface are selected as the processing object to solve the key to the ordinary processing method. The biggest characteristic of CNC machining is to use the perforated belt (or tape) control machine tool for automatic machining. Aircraft, rocket and engine parts have different characteristics: zero aircraft and rocket zero, large component size and complex surface; engine zero, small component size and high accuracy. Therefore, the aircraft, rocket manufacturing department and engine manufacturing department are different. In aircraft and rocket manufacturing to use continuous control of large CNC milling machine, and in engine manufacturing Continuous control of CNC machine tools, also use point control of CNC machine tools (such as CNC drilling machine, CNC boring machine, machining center, etc.).

CNC machining has the following advantages:

1.Basically reduce the number of tooling, processing complex parts do not need complex tooling. To change the shape and size of the parts, we only need to modify the part processing procedures, which are suitable for the development and modification of new products.

2.Stable processing quality, high processing accuracy, high repetition accuracy, to meet the processing requirements of the aircraft.

3.Under the condition of multiple variety and small batch production, the production efficiency is high, which can reduce the production preparation, machine tool adjustment and process inspection time, and reduce the cutting time due to the use of the optimal cutting amount.

4.Routine processing methods are difficult to process complex surfaces, and even can process some processing parts that cannot be observed.

The disadvantage of CNC machining is that the machine tool equipment is expensive and requires the maintenance personnel to have a high level.