HISTORY OF NC AND CNC

HISTORY OF NC AND CNC

The Origins of Numerical Control (NC)

The concept of Numerical Control (NC) emerged in the late stages of World War II to meet the U.S. Air Force's need for complex aircraft components. At that time, existing manufacturing techniques and conventional machines could not produce such intricate parts. To address this challenge, Parsons Corporation and MIT University collaborated on developing a solution.

In 1952, the Cincinnati-Hydrel company equipped a milling machine with Numerical Control (NC), marking the first successful application in this field. Following this breakthrough, NC machine production began, revolutionizing manufacturing.

Initially, NC programs were manually written and transferred to punched paper tapes via a tape punching unit. These tapes were then read by a paper tape reader, which sent signals to the machine’s motors. The motors, upon receiving the signals, would rotate the connected spindles to execute machining operations.

As computer technology advanced, NC machines evolved into CNC (Computer Numerical Control) machines. The introduction of onboard computers eliminated the need for paper tapes and significantly improved precision, flexibility, and automation.

What are NC and CNC?

NC (Numerical Control) Machines

NC machines operate based on alphanumeric codes, which are written in a structured sequence and interpreted by the machine. However, NC machines lack built-in computers and rely entirely on punched paper tapes to execute commands.

CNC (Computer Numerical Control) Machines

CNC machines are an advanced form of NC machines, integrating computerized control systems to manage machining operations. In CNC machines, NC codes dictate machine movements and actions, with each operation assigned a unique code.

For example, common CNC commands include:  GOO, G01, G02, G70, M03, M09, T0101, S2500, F0.25

Advantages of CNC Machines

Compared to conventional machine tools, CNC machines offer numerous benefits:

 Reduced Setup Time › Shorter preparation times before machining. Built-in Memory Storage › Programs and machine settings are saved for future use. Uninterrupted Data Retention › Even during power outages, data remains stored via backup batteries. Flexible & Easily Editable Programs › CNC programs can be modified in real time. Cycle-Based Operations › Frequently used machining cycles are pre-programmed,

reducing program length and error rates. Subprogram Utilization › Common machining operations are stored as subprograms, improving efficiency. Automatic Tool Compensation › When a cutting tool breaks, the CNC system automatically selects an alternative tool of a different diameter, without modifying the program. Optimal Speed & Feed Rates › CNC computers calculate ideal spindle speeds and feed rates for maximum efficiency. Superior Precision & Consistency › CNC machining ensures high accuracy and repeatability. Minimal Skilled Labor Requirement › CNC machines reduce dependence on highly skilled operators. High Operational Speed › CNC machines work continuously at maximum productivity levels. Lower Operating Costs › Electricity, material waste, and labor costs are minimized. No Need for Expensive Fixtures › Eliminates reliance on costly jigs, molds, and templates. Seamless Integration with Computers › CNC machines communicate with external systems for data analysis and remote monitoring. Pre-Machining Simulation › CNC programs can be simulated before execution, allowing error detection before actual machining begins. Automated Tool Changes › CNC systems automatically switch tools during machining processes.

Disadvantages of CNC Machines

Despite their advantages, CNC machines have some drawbacks:

High Initial Investment › CNC machines require significant upfront costs. Detailed Production Planning Required › CNC operations demand precise scheduling and programming. Higher Hourly Machine Costs › CNC machines have a higher operational cost per hour. Expensive Tooling & Accessories › Specialized cutting tools and fixtures increase costs. Strict Maintenance & Cleaning Requirements › CNC machines require regular servicing to maintain efficiency. Professional Maintenance Needed › Periodic inspections by trained specialists are essential to prevent malfunctions.