NC Milling Machine Guide
Contents
NC milling machines are the combination of a traditional milling machine and the NC (numerical control) system. In the following, we are going to put the focus on what NC is, the types, and the pros and cons of the NC system.
What is Numerical Control?
Numerical control, commonly known as NC, is commonly used in machine tools. It is an early form of automatic machining, which works based on the control of programming. This is a mechanism where the system commands a machine through numbers. The commands are translated into codes by the programmer so that the machine tool can understand and execute.
Where is NC Technology Used?
The NC technology is applied to operations such as assembly, inspection, drafting, sheet metal working, and more. However, it is more significantly used in machining sectors including milling, turning, drilling, etc. because of the motion control it provides. The motion control is carried out by 3-axis machining.
NC 3-axis Machining
The three basic motion controls are point-to-point control, straight cut control, and contouring control system. These three types of motion are defined by the X, Y, and Z-axis. On an NC milling machine, the X and Y axes refer to the longitudinal and traverse motion of the worktable, and the Z-axis refers to the vertical movement of the tool. The NC milling machine can perform the 3-axis machining more efficiently and accurately compared to the manual control machines.
NC and CNC, Saad Fahim
Advantages
NC system is best applicable under some circumstances. First of all, NC machining can handle batch production and repeat orders. Though not so flexible as CNC machining, it is effective when it comes to dealing with repetitive operations. NC milling machines are also useful when removing a large amount of material from the starting workpiece.
Compared to the conventional manual milling machines, the NC mills reduce the nonproductive time (setup time) while improving the accuracy and repeatability. Therefore, the production lead time is much shorter. Furthermore, it allows for more complex part geometries but requires lower skill-level operators.
Disadvantages
The disadvantages include higher investment costs and maintenance effort. An NC milling machine costs higher than a manual-control machine. Since the machine is more sophisticated than its manual counterparts, it takes more skills to maintain and more components to inspect. The other advantage is that, because the NC system is harder to program, it needs more skilled programmers.
Though they are more expensive and take more effort to care for compared to manual machines, they are actually less expensive and complicated than CNC machines. On this note, the NC machines provide a good choice for relatively intricate tasks and a lower budget.
Types of NC Systems
The conventional NC machines are hardwire-controlled. The control is carried out by punched paper (or plastic) tapes or cards. Tapes tend to deteriorate and thus cause misreading. On the other hand, the tapes are loaded/unloaded manually and the freedom to programming is not enough for today’s needs. Therefore, two more advanced NC types are developed: CNC and DNC.
CNC
Computer numerical control (CNC) is a type of NC system whose machine control unit is based on a microcomputer rather than on a hard-wired controller. It can work with various forms of program input such as magnetic, diskettes, RS communication, just to name a few. The major advantage of CNC is that it allows for great freedom to programming and the system communicates with the machine tool through software.
DNC
DNC today refers to Distributed Numerical Control. It represents a network consisting of a central computer connected to machine tool control units (CNCs). DNC is needed when the available memory of the machine control unit is too small to contain programs. DNC allows multiple units to store programs and distributes them as required to the machine tool to perform complex tasks.
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