The History of CNC Machining
Learn about the origins of this versatile manufacturing process.
CNC (Computer Numerical Control) machining refers to the process of manufacturing a part by the removal of material with a cutting tool that is under automated control as opposed to manual control by a machinist. This cutting tool can either be held stationary, with the part moving, or the tool can be rotated and moved into a piece of stationary material. CNC machining is often performed on metals but can also be employed with plastics and composites.
CNC machining has revolutionized the manufacturing industry since it was first introduced in 1952 in the form of the Cincinnati Milacron Hydrotel. Since then, advanced robotics systems have been incorporated into the machines to dramatically improve productivity and ultimately reduce the labor requirements for the manufacturer of components.
This article will cover CNC machining's history, how CNC machining works, and some of the more common use cases for this process.
CNC (Computer Numerical Control) machining refers to a type of subtractive manufacturing that is designed for manufacturing a part automatically by either advancing a spinning cutting tool mounted on a spindle into the work material (CNC mill) or by mounting the raw stock onto a spindle and moving it into a stationary tool (CNC lathe). The main function of a spindle in a CNC machine is to provide rotational motion to allow for the cutting of material.
An operator is required to set up the part to be machined by generating a list of instructions that tell the machine where to move the tool, at what speed, and how deep to cut the material per pass. This code was originally written by hand but is now handled by advanced software systems. Once the program instructions have been entered into the machine controller, the operator places the raw material into its starting position and initiates the machining sequence. The CNC machine then performs the planned manufacturing process steps. CNC machines have varying degrees of automation. Fully automatic machines can even load raw material and unload finished parts by means of a robot arm, as shown in Figure 1 below:
Robotic hand machine tool.
Image Credit: Shutterstock.com/asharkyu
John T. Parsons was the first person to invent and build an NC (Numerical Control) machine. The NC machine was designed to operate directly off a set of punch cards that tell the machine where to move. This concept laid the groundwork for the further development of the CNC machine. A team of researchers working at MIT (Massachusetts Institute of Technology), led by J.F. Reintjes, developed the first prototype CNC milling machine. Richard Kregg then collaborated with MIT to develop the Cincinnati Milacron Hydrotel, the first commercially available CNC machine. Cincinnati Milacron became one of the first manufacturers of CNC machines.
The CNC machine was created to allow for the machining of complex shapes that could not be manufactured with traditional manual milling techniques. CNC machining allowed for mathematically developed profiles that trace out a complex non-linear curve to be machined, which would be difficult if not impossible to accomplish with manual machining.
The objective of CNC machining is to produce precise parts in a repeatable manner with as little human intervention as possible. This ultimately results in lower cost per part while maintaining high levels of quality.
NC (Numerical Control) machines were developed before CNC (Computer Numerical Control) machines. NC machines were programmed with punch cards and later by magnetic tape. Ultimately, no computer is used, and the principal is similar to old automatic pianos that used punch card rolls to play music. These instructions were read by the machine, which then manufactured the part.
The first use of the CNC machine was to machine helicopter blades using mathematically developed aerofoil shapes in 1949.
Almost every industry makes use of CNC machining in some form. However, the primary users of CNC machining are listed below:
- Automotive: Combustion engines require exact tolerances to operate efficiently. For example, the cylinder head and gearbox are typically manufactured using CNC machining.
- Aerospace: The aerospace industry uses CNC machining extensively due to the requirements for repeatable and precise machining. Some typical applications include turbine blades, rocket combustion chambers, and hydraulic manifolds.
- Medical: The medical industry often requires components that have complex geometries with small tolerances to fit up to and align with human limbs and joints. This is a perfect use case for CNC machining, and some typical components include hip joints, surgical tools, and prosthetic limbs.
- Electronics: Electronic components require extreme precision. For that reason, CNC machining is used extensively in this industry. Some typical applications include consumer product enclosures to protect sensitive electronics, heat sinks, and wafer chucks and wafer carriers for electronic components like semiconductors.
CNC machining began gaining popularity in the late 1960s. In 1976, the first CAD (Computer Aided Design) systems were made available that allowed for the creation of 3D models that were then used to develop machine G-code. This allowed easier access to CNC technology. By 1989, CNC machining was considered the standard for large-volume manufacturing and production.
CNC machining has allowed increased manufacturing productivity by speeding up the machining process through automation. It has also allowed for increased quality and dimensional repeatability, ultimately creating more reliable and safer parts. CNC machining has also reduced the cost of manufacturing advanced components by reducing the overall labor requirements. , which ultimately allows manufacturers to offer products to consumers at a lower price point.
CNC machines make use of a programming language called G-Code (Geometry Code). This code is a relatively simple programming language that lists out a series of XYZ coordinates to where the tool must move and indicates the desired tool speed. There also exists a series of M-Codes (Machine Codes) that allow the operator to specify machine functions such as turning on coolant, changing a tool, and stopping the spindle, for example.
Yes, CNC machining is considered an advanced manufacturing technique because it automatically makes parts with little to no human intervention.
CNC machining covers a very broad range of machines with different capabilities. However, at the most basic level, CNC machines can be broken down into CNC lathes and CNC mills. A CNC lathe will spin the material into a stationary cutting tool, whereas a CNC mill will spin the cutting tool into stationary material. It must be noted that many variations of these tools exist, with some performing the functions of a lathe and a mill in the same machine. The number of degrees of freedom is also used to classify the type of CNC machine. For example, a 3-axis CNC machine can move the tool back and forth on the XY plane, as well as up along the z-axis. For more information, see our guide on the 12 Types of CNC Machines.
NC (Numerical Control) refers to the process of programming a machine with a set of machining instructions either on a punch card or on a magnetic tape. NC was developed in 1949 and is the predecessor to modern CNC (Computer Numerical Control). A machine will be said to have CNC control if it takes in a set of computer-generated codes to tell the machine where to move the tool and at what speeds in order to machine the final part.
The article reviewed the origins and history of CMC machining and its evolution from NC machining. To learn more about CNC machining and how you can use it for your projects, contact a Xometry representative.
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