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Okuma America Corporation
MACHINE DEFINITIONMACHINE DEFINITION
MACHINE DEFINITIONMACHINE DEFINITION
MACHINE DEFINITION
Rev. 8-21-01
Machine Tool
A machine tool is a power driven machine used to shape solid work by removing material
with a suitable cutting tool or by deformation of the metal.
Numerical Control Machine
A Numerical Control (NC) machine is a machine tool whose actions is controlled by direct
insertion of numerical data by way of coded instructions. An NC machine is positioned
automatically along a pre-programmed path by these coded instructions. These instructions
are letters, numbers, and other symbols that are translated into binary code.
Computerized Numerical Control Machine
A Computerized Numerical Control (CNC) machine is an NC machine that uses a computer
as the control system. A CNC is composed of two major components: the machine tool and
the Machine Control Unit (MCU). The CNC improved the handling of machine data (coded
instructions) which resulted in increased speed and accuracy of the machine tool.
A CNC needs at least four hardware items to exist:
1. Main Processing Unit - The main processing unit has a central processing unit (CPU)
which is the nerve center or main controller of the CNC and an Arithmetic/Logic Unit
(ALU) which handles all arithmetic and logical functions within the control. With the
miniaturization of electronic circuits, the CPU and ALU circuitry are built into the same
IC chip and have adopted the name microprocessor (µp).
2. Memory - The memory stores all data, whether temporary or permanent, that is used by
the microprocessor.
3. Servo System - The servo control system is needed to control axis movement and spindle
rotation.
4. Input/Output system (I/O) - This area of the (CNC) carries out the sending and receiving
of information to external devices.
The following information describes these four areas in more detail to give the student a
basic understanding of how a control functions:
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