- published: 30 Jun 2014
- views: 785703
Numerical control (NC) refers to the automation of machine tools that are operated by abstractly programmed commands encoded on a storage medium, as opposed to controlled manually via handwheels or levers, or mechanically automated via cams alone. The first NC machines were built in the 1940s and 1950s, based on existing tools that were modified with motors that moved the controls to follow points fed into the system on punched tape. These early servomechanisms were rapidly augmented with analog and digital computers, creating the modern computer numerical control (CNC) machine tools that have revolutionized the machining processes.
In modern CNC systems, end-to-end component design is highly automated using computer-aided design (CAD) and computer-aided manufacturing (CAM) programs. The programs produce a computer file that is interpreted to extract the commands needed to operate a particular machine via a postprocessor, and then loaded into the CNC machines for production. Since any particular component might require the use of a number of different tools-drills, saws, etc., modern machines often combine multiple tools into a single "cell". In other cases, a number of different machines are used with an external controller and human or robotic operators that move the component from machine to machine. In either case, the complex series of steps needed to produce any part is highly automated and produces a part that closely matches the original CAD design.
Silent night, holy night,
All is calm, all is bright
Round yon virgin mother and child.
Holy infant so tender and mild,
Sleep in heavenly peace.
Sleep in heavenly peace.
Silent night, holy night,
Shepherds quake at the sight,
Glories stream from heaven afar,
Heavenly hosts sing alleluia;
Christ the Savior, is born!
Christ the Savior, is born!
Silent night, holy night,
Son of God, love's pure light
Radiant beams from thy holy face,
With the dawn of redeeming grace,
Jesus, Lord, at thy birth.