What is the introduction of CNC machining?

08 Apr.,2024

 

Table of Contents


Computer Numerical Control (CNC) machining is a manufacturing process in which pre-programmed computer software dictates the movement of factory tools and machinery. The process can be used to control a range of complex machinery, from grinders and lathes to mills and CNC routers. With CNC machining, three-dimensional cutting tasks can be accomplished in a single set of prompts.

 

The CNC process runs in contrast to — and thereby supersedes — the limitations of manual control, where live operators are needed to prompt and guide the commands of machining tools via levers, buttons and wheels. To the onlooker, a CNC system might resemble a regular set of computer components, but the software programs and consoles employed in CNC machining distinguish it from all other forms of computation.

If you’re interested in utilizing CNC manufacturing to produce various products, find out more about how CNC machining and CNC programming works. You might also want to know about the main types of CNC machinery and the kind of work it can do to see if it can meet your needs.

What is CNC Machining?

When a CNC system is activated, the desired cuts are programmed into the software and dictated to corresponding tools and machinery, which carry out the dimensional tasks as specified, much like a robot.

In CNC programming, the code generator within the numerical system will often assume mechanisms are flawless, despite the possibility of errors, which is greater whenever a CNC machine is directed to cut in more than one direction simultaneously. The placement of a tool in a numerical control system is outlined by a series of inputs known as the part program.

With a numerical control machine, programs are inputted via punch cards. By contrast, the programs for CNC machines are fed to computers through small keyboards. CNC programming is retained in a computer’s memory. The code itself is written and edited by programmers. Therefore, CNC systems offer far more expansive computational capacity. Best of all, CNC systems are by no means static since newer prompts can be added to pre-existing programs through revised code.

CNC Machine Programming

In CNC manufacturing, machines are operated via numerical control, wherein a software program is designated to control an object. The language behind CNC machining is alternately referred to as G-code, and it’s written to control the various behaviors of a corresponding machine, such as the speed, feed rate and coordination.

Basically, CNC machining makes it possible to pre-program the speed and position of machine tool functions and run them via software in repetitive, predictable cycles, all with little involvement from human operators. In the CNC machining process, a 2D or 3D CAD drawing is conceived, which is then translated to computer code for the CNC system to execute. After the program is inputted, the operator gives it a trial run to ensure no mistakes are present in the coding.

Due to these capabilities, the process has been adopted across all corners of the manufacturing sector, and CNC manufacturing is especially vital in the areas of metal and plastic production. Find out more about the types of machining systems used and how CNC machine programming fully automates CNC manufacturing  below:

Open/Closed-Loop Machining Systems

During the CNC manufacturing process, position control is determined through an open-loop or closed-loop system. With the former, the signaling runs in a single direction between the CNC controller and motor. With a closed-loop system, the controller is capable of receiving feedback, which makes error correction possible. Thus, a closed-loop system can rectify irregularities in velocity and position.

In CNC machining, movement is usually directed across X and Y axes. The tool, in turn, is positioned and guided via stepper or servo motors, which replicate exact movements as determined by the G-code. If the force and speed are minimal, the process can be run via open-loop control. For everything else, closed-loop control is necessary to ensure the speed, consistency and accuracy required for industrial applications, such as metalwork.

CNC Machining Is Fully Automated

In today’s CNC protocols, the production of parts via pre-programmed software is mostly automated. The dimensions for a given part are set into place with computer-aided design (CAD) software and then converted into an actual finished product with computer-aided manufacturing (CAM) software.

Any given workpiece could necessitate a variety of machine tools, such as drills and cutters. In order to accommodate these needs, many of today’s machines combine several different functions into one cell.

Alternately, an installation might consist of several machines and a set of robotic hands that transfer parts from one application to another, but with everything controlled by the same program. Regardless of the setup, the CNC process allows for consistency in parts production that would be difficult, if not impossible, to replicate manually.

CNC Machining is often the last step in metal manufacturing, or sometimes the only process involved. Compared to other metalworking techniques, CNC machining is capable of meeting the tightest tolerances, and producing the most accurate, precise products over and over again.

To understand the origins of CNC Machining, it's important to break the phrase down into three parts:

  • First, "machining," or the process of removing metal with the assistance of mechanical equipment, has been around for centuries. Machining processes include: turning, drilling, milling, shaping, broaching and grinding.
  • Next, "NC" stands for "Numerical Control." In traditional machining, a human operator must control the motion of a machine tool. Numerical control, first developed in the 1940s, governs the motion of machines automatically, through set instructions.
  • Finally, the "C" gets added. "Computer Numerical Control" designates a process by which an operator can write, adjust and implement instructions using a computer console. This addition, which took place in the 1950s, is what makes modern machining possible.

History of CNC Machining

In the late 1940s, John Parsons of Parsons Corp. in Traverse City, MI, developed a system to control machining equipment by feeding it punched cards with holes corresponding to coordinates. Starting in 1949, Parsons joined the U.S. Air Force at an MIT laboratory to further develop what was to become numerical control.

The team behind numerical control developed a process to produce aircraft parts that required a high degree of accuracy and precision, and took manual operators hours to work through. With the addition of numerical control, part after part could be produced with little human oversight.

The Advent of CNC

While early NC systems were revolutionary in their own right, there was still plenty of room for improvement. For starters, machine tools had to be programmed using a tedious process, and errors were common. Different companies developed different programming languages, resulting in confusion and incompatibility that, at first, stymied the growth of NC machining.

The U.S. Air Force stepped in once again, funding research at MIT to develop a universal NC programming language, which was first unveiled in 1959. Versions of the programming language, called Automatically Programmed Tools (APT) are still in use today.

In 1959 when APT was developed, computers weren't quite mainstream, but the technology grew quickly enough. Early NC machines could be programmed and controlled by small computers attached to each machine.

These days, many CNC machine shops make use of Distributed Numerical Control (DNC), which allows a programmer to control several CNC units from a central computer. Many CNC interfaces are built around user-friendly software, and require much less training to operate than their forebears.

The Future of CNC Machining

As global demand for CNC machined products grows and changes, a wide variety of innovations are currently taking place in the CNC machining industry.

Robotics - more than just mills and lathes, CNC is increasingly being applied to industrial robotics. In some factories, machines not only handle tasks like cutting and welding, but also transportation and assembly.

3D Printing - both a competitor to CNC machining and a complementary process, industrial 3D printing is also growing rapidly. While machining is a subtractive process–starting with solid stock and cutting away material to form a shape–3D printing is additive. In many cases, designers can 3D print a prototype, and use it as a pattern to configure CNC equipment. In other cases, products can be accurately and precisely 3D printed straight from design software.

At-Home CNC - The market for DIY CNC kits and inexpensive CNC machinery has grown exponentially over the past few decades. While they don't offer anything new in terms of processes, these at-home CNC stations make product development easier, faster and cheaper than ever. With the financial burden of metalworking vastly decreased, there's no telling what inventive products might come out of a hobbyist's garage.

Learn more about CNC Machining

Want to know more about CNC machining processes and equipment? Download our free ebook, CNC Machining Process Guide.

 Image of CNC punch tape operator courtesy of Three Quater Ten on Wikipedia

What is the introduction of CNC machining?

Introduction to CNC Machining