How CNC Machining Will Benefit Your Production Process

Computer Numerical Control (CNC) machining is a subtractive manufacturing process in which the movement of factory tools and machinery are being dictated by a pre-programmed computer software that can be run in repetitive, predictable cycles, and with little involvement from operators. With this manufacturing process, three-dimensional cutting tasks to remove layers of materials from a workpiece can be accomplished in a single set of command, unlike the manual control in which the operators have to guide the commands of the machining tools through levers, buttons, and wheels. CNC machining is suitable for a wide range of materials such as metals, plastics, wood, glass, foam, composite, and machining of parts and prototypes for industries such as telecommunications, automotive, aerospace, construction, agriculture, etc. Most materials can be machined with CNC if they can withstand the machining process – specifically the material’s hardness, tensile and shear strength, and its resistance to chemical and temperature.

To activate a CNC system, a two or three-dimensional computer-aided drawing of the desired cuts is conceived. These desired cuts are programmed into the software by translating it into computer code and dictating it to the corresponding tools and machinery which will in turn do the tasks as often as specified. Depending on the program, a CNC machine can cut in more than one direction simultaneously. These programs are fed to the computers through small keyboards and retained in its memory. The programmers write and edit the code themselves because CNC machining relies heavily on programming, and the language behind CNC machining is referred to as the G-code (general or geometric code) – which controls the behaviors of the machine in terms of its speed, feed rate, location, and coordination. After inputting the program, the operator performs a trial run on the CNC machine to ensure that there are no mistakes in the coding. Initiating the program prompts the CNC machine to begin the CNC machining process, and this processing can be performed in-house if the company has their own CNC equipment or out-sourced to CNC machining service providers.

The evolution of CNC began with NC, which means numerical control. The earliest numerical control machines were first introduced by the US Air Force mechanics in the 1940s, in which motors were used to control the movement of the tools. Then, these machines were enhanced as technologies advanced until it led to the birth of CNC machining. It makes the work of many industries easier, making CNC machining one of the most used machining across the manufacturing industry.

Despite being dictated by pre-programmed computer software, CNC machining can be used differently according to what the various CNC machines are expected to do. Some of the most common mechanical CNC machining operations are: drilling, turning, and milling.

• CNC Drilling – Drilling is a machining process which produces cylindrical holes in the workpiece through rotating multi-pointed drill bits. There are several types of drill bits, such as: spotting drills for producing shallow or pilot holes, peck drills for reducing the amount of chips on the workpiece, screw machine drills for producing holes without a pilot hole, and chuckling reamers for enlarging previously produced holes. When it comes to CNC drilling, the CNC machine feeds the rotating drill perpendicularly to the plane of the workpiece’s surface to produce vertically-aligned holes with diameters which is similar to the diameter of the drill bit employed for the drilling operation. Aside from this, the use of specialized machine configurations and workholding devices can also perform angular drilling operations. The CNC drilling process has operational capabilities such as counterboring, countersinking, reaming, and tapping.
• CNC Turning – Turning is a machining process in which a single-pointed cutting tool is used to remove unwanted material from a rotating workpiece. The machine for CNC turning, which is called the CNC lathe, feeds the cutting tool in a linear motion along the surface of the rotating workpiece to produce the desired cylindrical parts with internal and external features. There are different types of lathes available, such as turret lathe, engine lathes, and special purpose lathes. Depending on the needs for the end product, the design of the turning tool varies and some of these tools can be used for roughing, finishing, facing, threading, forming, undercutting, parting, and grooving applications.
• CNC Milling – Milling is a machining process in which rotating multi-bladed cutting tools are used to remove material from a stationary workpiece. It is either vertically or horizontally oriented and unlike the manual milling in which the machine feeds the workpiece in the opposite direction to the cutting tool’s direction, the CNC machine feeds the workpiece to the cutting tool in the same direction as the cutting tool’s rotation in CNC milling. The CNC milling process has basic mills that are capable of three-axis movements, however, technological advances made way for creating additional axes. There are different types of mills such as hand milling, plain milling, universal milling, and omniversal milling machines.

CNC machining is very beneficial to various manufacturing industries because it is fully automated, which makes the production faster and easier. It also provides flexibility because when there is a need to add new prompts to pre-existing programs, it can be done through revising the code. With the computer-aided (CAD) software, the dimensions for a given part are set into place for the computer-aided manufacturing (CAM) software to convert it into an actual finished product. The pre-programmed software allows the CNC machining to be consistent in parts production that is difficult if done manually. The endurance of CNC machines is also an advantage because it can operate as much as needed, except for when it undergoes maintenance or repair. It also provides a safe environment for the operators because they are not going to come into direct contact with the sharp tools, unlike in manual machinery. In addition, there is not much of a need for operator intervention in CNC machining because of its automation and this reduces the likelihood of mistakes caused by operator fatigue or human error. The CNC machining, however, requires having skilled and knowledgeable CNC machinists and programmers to operate the machinery. Aside from that, the cost of CNC machining may be a little higher compared to other fabrication methods but it is advantageous in terms of labor cost, speed, production rate, and accuracy. So as long as the machining is not just used entirely for small and simple operations, the cost can be an advantage in the long run. Therefore, CNC machining is usually the best choice for big and competitive industries.

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