User:Amenreus/Sandbox

Shortcut of CNC means Computer Numerical Control. CNC are machines controled by computer.

History

History of CNC machines begans in 19th century. In this century was founded that with help of computer machining machines can make better and more accurate shapes. They founded that when they needed to make rotor blades for helicopter where is necessary to have the exact shape, but this shapes are difficult and their making is complicated. With CNC machines this process became much more easier. CNC machines for machining has experienced a boom in 19th centruy, when they were used not only for machining but in other branches too. They are now used for turning, milling, grinding, welding, cutting etc.

Kinds of CNC machining

Conventional

• Turning
• Milling
• Grinding
• Cutting
• Lapping
• Superfinishing
• Polishing

Unconventional

• Laser machining
• Plasma machining
• Electron beam machining
• Ultrasound machining
• Electroslag machining
• Water jet machining

Tools

Tools used for CNC machining are made from tool steel 19th class (by ČSN - czech national standard) and from cemented carbide. Cemented carbides are divided into categories by its chemical composition or by their use into class (by ISO 513):

• P - used for machining of carbon steel, tool steel, alloyed steel etc.
• M - used for machining of heat-resistant steel, corrosion resistant steel, heat resisting steel etc.
• K - used for machining of gray cast iron etc.
• N - used for machining of alloy of Al and Cu and other non-ferrous metals
• S - used for machining of special heat resisting alloy based on Ni, Co, Fe a Ti
• H - used for machining of hardened cast iron and refined steel

Programming

There are two ways how to program CNC machine. You can write whole program by yourself (useful for short and simple workpieces) or you can use CAD and CAM software (for complex workpieces).

CAD (computer aided design)

We use CAD programs for drawing 2D design or 3D model of workpiece which we want to make.

Programs

• SolidWorks
• SolidEdge
• Catia
• AutoCAD

CAM (computer aided manufacturing)

When we have complete model of workpiece we now can make step forward and start with programming machining process. First we have to convert 3D model to CAM program and then we can define all axis, operations, tools and parameters of machining. Then we have to generate machine code by postprocessor. Selection of postprocessor depends on type of machine control system for which we generate machine code (for example: Fanuc, Siemens, Heidnhaim, Emco, etc).

Programs

• SolidCAM
• SurfCAM
• AlfaCAM
• F2000
• S2000
• Heidnhaim
• Inventor

Use

CNC machines are commonly used in serial production or for machining of atypical parts. Special case of their using is flexible manufacturing system. Many CNC machining centers are connected to one central computer. Great advantage of FMS is its flexibility in change of parts production and its automatization.