Friday, October 30, 2015

The Different CNC Machines (part 2 of 2)

Electrical discharge machine

An electrical discharge machine (EDM) creates cavities in metals by emitting electric sparks. This process requires an electrode, coolant, a power source, and a tank. The cycle is accomplished by connecting the workpiece to one side of the power supply and then placing it in the tank. An electrode (made in the shape of the cavity required) is then connected to the other side of the power supply.

The tanks is then filled with coolant and the electrode is lowered until a spark jumps between the work and the electrode. As the coolant is a dielectric substance (resists electric currents), it requires a smaller difference in distance in order for a spark to jump through. This means that when the spark appears, the dielectric property has been overcome. The spark then dislodges material thereby creating a cavity in the shape of the electrode.

CNC systems

CNC systems are complex machines that transfer and store data regarding the operation mechanism of the machines. Motion programs include point to point control, straight cut control, and contouring control.

Point to point control means the control of the tools from one point to another in the coordinate plane. This method of control is commonly used in drilling and boring operations.

Straight cut control is the method by which a tool is moved in all axes of the machine. The tool also has the ability to move in a 45 degree angle.

Contouring control is the means to create a toolpath. It moves the tools by interpolating points or coordinates that make up the path for the tool to follow.

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