Shaping our tools to shape the world has now become a thing of past. Now our machines are shaping it. Being wrist deep in wood or metal shavings and having swollen hands with scars of imperfection on them, but still struggling to bring the creations to life. This is what a mechanical engineers work looked like before they met CNC machines. It is a major advance in machining, and is a vast improvement over non-computer type machining that requires manual control. In modern CNC systems, the design of a mechanical part and its manufacturing program is highly automated. Consequently it automatically controls machining tools (drills, boring tools, lathes) by means of a computer. A CNC machine operates on a piece of material (metal, plastic, wood, ceramic, or composite) to transform it to precise specifications.
Types of CNC machines
CNC machines are further classified as following types:
Drills: it works by spinning a drill bit and moving the bit about and into contact with a stationary block of stock material.
Lathes: they are designed for precisely machining relatively hard materials. These rigid machine remove material from a rotating workpiece via the (typically linear) movements of various cutting tools, such as tool bits and drill bits.
Milling Machines: Milling machines are probably the most common CNC machine in use today. They involve the use of rotary cutting tools to remove material from the stock unit.
Routers: Routers are generally used for producing larger dimension parts and more commonly built with the idea of cutting wood, plastics and sheet metal in mind. Routers also are most commonly found in a 3 axis Cartesian coordinate setup (X, Y and Z). A 3 axis set up will allow cutting of profiles, pocketing and 3 dimensional relief machining.
Almost any material can be used in a CNC machine. It really depends on the application. Common materials include metals such as aluminum, brass, copper, steel, and titanium, as well as wood, foam, fiberglass, and plastics such as polypropylene.
4 Steps to use CNC
First step is to design the part you want to build. CAD software are used to create 3-d or 2-d models. Further CAD software assist you with accurate drawing; be that converting your hand drawn sketches to a digital version, also known as Computer Aided Drawing, or designing something from scratch. These drawings are used for analysis and CNC machining production. There are different software for creating CAD designs and almost all software has the capability to create a precise model for CNC production.
CNC machine can also be coded manually but there might be a mistake in doing so. As code contains a lot of information in it and works using one instruction at a time so if something is interpreted wrong then it might ruin the whole geometry of the part you want.
Next comes Computer-aided manufacturing (CAM). Computer-aided manufacturing (CAM) is the use of software to control machine tools and related ones in the manufacturing of workpieces. Without CAM, there is no CAD. CAD focuses on the design of a product or part. How it looks, how it functions. CAM focuses on how to make it. You can design the most elegant part in your CAD tool, but if you can’t efficiently make it with a CAM system then you’re better off kicking rocks. When a design is complete in CAD, it can then be loaded into CAM. This is traditionally done by exporting a CAD file and then importing it into CAM software. Once your CAD model is imported into CAM, the software starts preparing the model for machining. Machining is the controlled process of transforming raw material into a defined shape through actions like cutting, drilling, or boring.
Last but surely not the least, comes telling the machine what to do. So you need to provide it with the G code. Which contains contains the instructions for the machine to operate at certain angles, for a specified time, repetitive cycles, coordinates and rotation speed of the tool being used. Now, this G-code is the instruction for the computer, controlling different tools, to generate the desired parts. This code works in small parts. Each line of the code has the information about the part that is to be generated from a raw material block.
CNC machines have helped industries in increasing in the quality of products as well as offering high flexibility. It increases the productivity and reduces the lead-time. The production is economical in nature and decreases the amount of scrap generated and is the way forward for manufacturing industry. I hope this article was helpful for you to learn the basics of CNC machine and has given you a idea of how to use it.
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