More on CNC (Computer Numerically Controlled)

CNC Defined

CNC stands for Computer Numerically Controlled. CNC refers to how a machine operates, that is, its basic method of controlling movement, e.g., a CNC machine uses a stream of digital information (code) from a computer to move motors and other positioning systems in order to guide a spindle or other tooling over raw material.

A CNC machine uses mathematics and coordinate systems to understand and process information about what to move, to where, and how fast. Most CNC machines are able to move in three controlled directions at once. These directions are called axes and are given simple names such as X, Y and Z (based on the Cartesian Coordinate System). The X axis is always the longest distance a machine or a part of a machine must travel. X may be the movement from front to back, Y the movement from left to right, and the Z is almost always vertical movement (normally the spindle's positioning movement up and down). Superior Machinery sells many types of CNC Machines, from CNC Horizontals, CNC Verticals to CNC Lathes; they have over 182 CNC Machines to choose from.

A CNC machine must be able to communicate with itself to operate. A computer numeric control unit sends position commands to motors. The motors must talk back to the control that, indeed, they have acted correctly to move the machine a given distance. The ability of CNC machines to move in three (or more) directions at once allows them to create almost any desired pattern or shape. All of this processing happens very fast, accurately and consistently.

CNC Historical Development

CNC technology was developed in the United States in the 1950's for the US Air Force by metalworking machine tool builders. It was a major advance in the ability of machines to faithfully reproduce complex part machining steps more accurately without human intervention or variability.

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 manually controlled 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.

Proliferation of CNC

The price of computer cycles fell drastically during the 1960s with the widespread introduction of useful minicomputers. Eventually it became less expensive to handle the motor control and feedback with a computer program than it was with dedicated servo systems. Small computers were dedicated to a single mill, placing the entire process in a small box. PDP-8's and Data General Nova computers were common in these roles. The introduction of the microprocessor in the 1970s further reduced the cost of implementation, and today almost all CNC machines use some form of microprocessor to handle all operations.

The introduction of lower-cost CNC machines radically changed the manufacturing industry. Curves are as easy to cut as straight lines, complex 3-D structures are relatively easy to produce, and the number of machining steps that required human action have been dramatically reduced. With the increased automation of manufacturing processes with CNC machining, considerable improvements in consistency and quality have been achieved with no strain on the operator. CNC automation reduced the frequency of errors and provided CNC operators with time to perform additional tasks. CNC automation also allows for more flexibility in the way parts are held in the manufacturing process and the time required to change the machine to produce different components.

During the early 1970s the Western economies were mired in slow economic growth and rising employment costs, and NC machines started to become more attractive. The major U.S. vendors were slow to respond to the demand for machines suitable for lower-cost NC systems, and into this void stepped the Germans. In 1979, sales of German machines surpassed the U.S. designs for the first time. This cycle quickly repeated itself, and by 1980 Japan had taken a leadership position, U.S. sales dropping all the time. Once sitting in the #1 position in terms of sales on a top-ten chart consisting entirely of U.S. companies in 1971, by 1987 Cincinnati Milacron was in 8th place on a chart heavily dominated by Japanese firms.

Many researchers have commented that the U.S. focus on high-end applications left them in an uncompetitive situation when the economic downturn in the early 1970s led to greatly increased demand for low-cost NC systems. Unlike the U.S. companies, who had focused on the highly profitable aerospace market, German and Japanese manufacturers targeted lower-profit segments from the start and were able to enter the low-cost markets much more easily. As computing and networking evolved, so did direct numerical control (DNC). Its long-term coexistence with less networked variants of NC and CNC is explained by the fact that individual firms tend to stick with whatever is profitable and their time and money for trying out alternatives is limited. This explains why machine tool models and tape storage media persist in grandfathered fashion even as the state of the art advances.

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Featured Machines

Machine 6397, Haas VF4SSAPC, Super Speed VF4, 2006, Pallet Shuttle, 12,000 RPM Spindle, 4th Axis, 24 Pocket Side Mount Tool Changer, High Speed Tool Changer, 4th Axis, Programmable Coolant Nozzle, Visual Quick Code Programming System
Haas VF4SSAPC, Super Speed VF4, 2006, Pallet Shuttle, 12,000 RPM Spindle, 4th Axis, 24 Pocket Side Mount Tool Changer, High Speed Tool Changer, 4th Axis, Programmable Coolant Nozzle, Visual Quick Code Programming System

Machine 6624, Okuma LB 4000EX-II/1500 CNC Universal Lathe, OSP P300L, 2015, Like New Condition
Okuma LB 4000EX-II/1500 CNC Universal Lathe, OSP P300L, 2015, Like New Condition

Machine 6634, Cincinnati-Milacron T-40 CNC Horizontal Machining Center, 1989, Full 4th Axis, 90 ATC, 60" x 60" x 58"
Cincinnati-Milacron T-40 CNC Horizontal Machining Center, 1989, Full 4th Axis, 90 ATC, 60" x 60" x 58"

Machine 6733, Lanson GT2-LS280B Plastic Injection Molding Presss 2015, TECH1_Q8M Controller, Variable displacement pump, 1 x Core puller, 4 x Air blast
Lanson GT2-LS280B Plastic Injection Molding Presss 2015, TECH1_Q8M Controller, Variable displacement pump, 1 x Core puller, 4 x Air blast

Machine 6703, Mori-Seiki RL2500 Dual Spindle 4-Axis Chuckers, 2005, Gantry Loaders, MSX-501 Controls, Chip Conveyors, Expanding Madrels, Two (2) Available
Mori-Seiki RL2500 Dual Spindle 4-Axis Chuckers, 2005, Gantry Loaders, MSX-501 Controls, Chip Conveyors, Expanding Madrels, Two (2) Available

Machine 6711, Fadal VMC-4020 HT, 2004, Fadal 32MP Control, Cool Power
Fadal VMC-4020 HT, 2004, Fadal 32MP Control, Cool Power

Machine 6713, Craven 127" x 360" Heavy Duty CNC Lathe, Rebuilt in 2015, Fanuc 0iTC, 4 way Bed Construction, 2 Carriages, 75 HP Main Drive
Craven 127" x 360" Heavy Duty CNC Lathe, Rebuilt in 2015, Fanuc 0iTC, 4 way Bed Construction, 2 Carriages, 75 HP Main Drive

Machine 6706, Gardner SDG-2-20-23 Double Disk Grinder, Upgraded to handle 23" Wheels, 20 HP, Capacity for 4" parts
Gardner SDG-2-20-23 Double Disk Grinder, Upgraded to handle 23" Wheels, 20 HP, Capacity for 4" parts

Machine 6710, CAE Ransohoff Rotary Parts Washer, 1999
CAE Ransohoff Rotary Parts Washer, 1999

Machine 6730, Lodge & Shipley 2XE 3220W, 1976, 32" x 72", 50 HP, 2.56" Spindle Hole, Steady Rest, 4-Way Rapid Traverse, Taper Attachment, DRO, Tailstock
Lodge & Shipley 2XE 3220W, 1976, 32" x 72", 50 HP, 2.56" Spindle Hole, Steady Rest, 4-Way Rapid Traverse, Taper Attachment, DRO, Tailstock

Machine 6240, Lehmann Oil Field Lathe, Double Chucked, 30" Swing, 360" CC, 9.57" Spindle Bore, 24"/21" Chucks, Taper attachment, Tailstock, Soft bed in very good condition
Lehmann Oil Field Lathe, Double Chucked, 30" Swing, 360" CC, 9.57" Spindle Bore, 24"/21" Chucks, Taper attachment, Tailstock, Soft bed in very good condition

Machine 6741, Deckel-Maho DMC 100 U DuoBlock, 2005, Heidenhain Mill Plus IT V600, 1100 x 910 mm pallet, 10K RPM, 120 ATC
Deckel-Maho DMC 100 U DuoBlock, 2005, Heidenhain Mill Plus IT V600, 1100 x 910 mm pallet, 10K RPM, 120 ATC

Machine 6750, CY 1530 SL 2.0KW Fiber Laser, 2012, 59" x 118", AIR 3000 Chiller, Farr Gold Series Packaged Dust Collector
CY 1530 SL 2.0KW Fiber Laser, 2012, 59" x 118", AIR 3000 Chiller, Farr Gold Series Packaged Dust Collector

Machine 6751, Edel 4030 5-Axis CNC Gantry Milling Machine, 2008, 157" x 118" x 45", Heidenhain TNC i530, Through Spindle Coolant
Edel 4030 5-Axis CNC Gantry Milling Machine, 2008, 157" x 118" x 45", Heidenhain TNC i530, Through Spindle Coolant

Machine 6615, Schmid T630 Cold Forming Press, 2002, 900 Short Tons Total Force
Schmid T630 Cold Forming Press, 2002, 900 Short Tons Total Force