Views: 4 Author: Site Editor Publish Time: 2022-07-07 Origin: Site
Suppose you've ever watched an episode of How It's Made. In that case, you probably know what lathes and other metalworking machines can do.
As technology has advanced over the years, it has given rise to a high-precision computer-controlled manufacturing technology we call CNC machining.
A CNC machine (computer numerically controlled machine) is an electromechanical device that operates a tool around various axes, usually three or five, each with high-precision instructions from a computer program.
The first CNC machines were developed in the 1940s and 50s and relied heavily on perforated tape data storage technology. The code that controlled the machine would be manually punched into a data card and then entered into the system, and the data was then interpreted.
As technological capabilities only accelerated in the late 20th century, CNC machining technology developed rapidly, understanding how modern CNC machines work.
How CNC manufacturing works
CNC machining is one of two ways an engineer or manufacturer can generate a physical part from a computer-aided design (CAD) file, the other being 3D printing, called additive manufacturing.
The contrast between these two technologies is stark. CNC machining is a subtractive process in which material is removed from inventory. On the other hand, 3D printing is an essentially opposite additive process.
CNC capabilities before CAD
Machining converts raw materials such as aluminum, steel, or titanium into finished products or parts.
CNC machines relied on digital instructions, specifically called G-code, before the advent of modern computer-aided manufacturing and computer-aided design programs like Autodesk's Fusion 360, and machinists would manually write G-code to control these machines.
Comparing the capabilities of automated CNC machining with manual alternatives such as lathes and other machining techniques, you will see the advantages.
CNC machines run faster with greater precision and accuracy while allowing digital designs to be converted into physical parts. CNC machines are exact, measuring thousands of inches.
Standard machining can provide part tolerances of approximately plus or minus 0.005 inches.
Finishing can produce tolerances of approximately plus or minus 0.001 inches.
Specialized processes such as polishing can provide repeatable tolerances to plus or minus 0.00005 inches.
For reference, human hair is 0.00069 inches thick.
CNC Machines: Models and Features
Now that we understand the basics of CNC machining, we can begin to delve into its intricacies. Many designs or specific machining processes require the use of multiple tools for cutting. One tool cannot be used universally.
For this reason, machinists often build digital tool libraries that interface with physical CNC machines. These machines, usually costing hundreds of thousands of dollars, can automatically switch tools with digital instructions, making them the workhorses of manufacturing.
3- and 5-axis mobility for CNC machines
Basic CNC machining will move one or two axes, called the X and Y axes. You will often hear the terms 0.2.5 axis, 3 axis, and 5 axis CNC machines, which refer to the degrees of freedom the machine can cut into.
A 3-axis machine will move in the X, Y, and Z axes. The 5-axis machine can move in all three axes and two additional axes of rotation.
5-axis machines used to be used only for high-precision machining. Still, as they become more affordable, they quickly become standard in many stores.
Three types of CNC machining tools: drilling, lathe, and milling
You need to understand three traditional machining techniques to learn how to remove material from stock in a CNC machine.
Drills work by rotating the drill and moving the bit to make contact with a fixed stock.
Lathes perform the opposite function of drilling. The lathe rotates a block of material onto a fixed drill or tool to remove material in a circular or fluid path. Lathes have more limited shape capabilities than other technologies. Still, modern technology does allow these machines to make things like square holes or non-circular shapes.
CNC Milling Machines
The most common type of CNC machine is called a milling machine. Milling machines involve using rotary cutting tools to remove material from raw materials. These machines function similarly to drills, with tooling capabilities covering a wider variety.
Almost any material, from plastic to titanium, can be used in a CNC machine. Different materials have different properties, so machinists and engineers will overcome their unique challenges by changing machining variables such as tool selection, RPM, feed rate, and coolant flow, among other factors.
Longevity of CNC machining
CNC machined parts are all around you. They hold your car together and perform vital functions on the SpaceX rocket. If you want to produce high-precision metal parts for engineering designs, CNC machining is the only way.
CNC machining is arguably the most critical manufacturing process of the 21st century, and its capabilities have driven technological advancements worldwide. It is an industry that keeps up with technology, and machinists worldwide use CNC machining skills to change the world.