Posted on Jan. 9th, 2019 | By Hailey, WayKen Project Manager
The introduction of numeric control has revolutionized the manufacturing industry through the use of CNC machining. The modern computer integrated manufacturing techniques are capable of producing complex geometries with high efficiency and at a lower cost rather than a conventional manufacturing process.
The manufacturers are now able to produce complex geometries with better accuracy and machining in lesser time as compared to conventional manufacturing methods. The modern integrated manufacturing techniques such as CNC which involves the use of the computer for tasks like drilling, boring, cutting operations serves as a favorable option for both prototyping and production of industrial and domestic products all around the world.
CNC machining is a manufacturing process involving the programmed CAD model is used to dictate the machining tools in order to produce products. The design and manufacturing of the mechanical parts in modern CNCs is highly automated. In CNC machining, the desired cuts and other techniques are programmed and fed into the machine which then carries out the specified tasks. Many industries are engaging the CNC machines for faster production of precise and highly efficient parts.
The modeling of the desired part or geometry is done on the modeling software. Modern modeling software has aided in the use of rapid prototyping techniques due to their easy interface which enables domestic as well as industrial customers to design the required geometry. The designed model defining the dimensions of the required geometry is then converted into the manufacturing directives by using CAM (Computer Aided Manufacturing) software. The transformation of the directives into specific commands such as G and M-codes is necessary for the particular machine to produce the component.
The motion of the tool on CNC is controlled along different axes. Modern CNC machines being employed are using the 5-axes machining. 5-axes machining enables the working tool to move along 5 different axes at the same time enabling machining of complex parts with complete efficiency and accuracy.
Manufacturing Directives: G-codes and M-codes
CNC machines are controlled by software using the numeric method. The language behind the programming of CNC is called G-codes and M-codes which are responsible for machine speed, feed rate, coordination and tool speed etc. The manufacturing directives created by the CAM software are in the form of G-codes and M-codes. They are basically based on the Cartesian coordinate system. After the 3D model is conceived and converted into the manufacturing directives, the operator gives a trial run to it ensuring that the codes are error free. In case of any error, new codes are generated by the CAM software by the amendments required.
G-codes are the manufacturing directives used to command some movements of the machine and tools. The format of the code is letter G followed by two or three numeric digits. G-codes for lathe and milling operation may differ from each other. Following are some G-codes and their functions:
- G00: Rapid Motion Positioning
- G01: Linear Interpolation Motion
- G02: Interpolation Motion-Clockwise
- G03: Circular Interpolation Motion-Counter Clockwise
- G04: Dwell (Group 00) Mill
- G10: Set offsets (Group 00) Mill
- G12: Circular Pocketing-Clockwise
- G13: Circular Pocketing-Counter Clockwise
Whereas M-codes are miscellaneous codes which are not responsible for the movement of machine or tool. The format of the code is letter M followed by two or three numeric digits. Following are some M-codes and their functions:
- M02: End of Program
- M03: Start Spindle - Clockwise
- M04: Start Spindle - Counter Clockwise
- M05: Stop Spindle
- M06: Tool Change
- M07: Coolant on mist coolant
- M08: Flood coolant on
- M09: Coolant off
- M10: Chuck open
- M11: Chuck close
- M13: BOTH M03&M08 Spindle clockwise rotation & flood coolant
- M14: BOTH M04&M08 Spindle counterclockwise rotation & flood coolant
These manufacturing directives are also responsible for the decision of the correct tool and feed speed for the smoother and efficient run of the machine. Wrong programming can lead to wrong speed which can damage the tool, spindle and the raw material being used for the part.
Types of CNC machines
CNC machining can be of different types depending upon the operation required by the manufacturer. Following are some of the types:
1. CNC Lathes
CNC lathe can perform the machining operations involving the cuts in a circular direction with a variety of tools which can be used depending upon the part’s specifications. CNC lathes can produce complex designs with precision and high velocity that would not be possible on the manual lathes. Most CNC lathes are two axes lathe machines which can function in X and Y coordinates.
2. CNC Milling
Milling is another CNC operation. It is an operation of producing complex and flat shapes with the use of multi-tooth cutting tools. Cutting tool’s axis of rotation is perpendicular to the feed direction. CNC milling is guided across various distances by the manufacturing directives. CNC machined parts are better in finishing as compared to manual milled parts. CNC milling and lathe are almost similar except with the differences in the G-codes and the axes where milling tool can be guided in 3 axes as compared to lathe tool that can be guided only in two axes.
3. Water Jet Cutters
In CNC machining, the water jet is used when there is need of cutting some hard material such as metals. In water jet cutting, high-pressure water jet produced by the nozzle is used to cut the material into the required size. Sometimes water is mixed with some sand particles in order to increase the pressure. Many parts are cut into the required shape by using water jet cutters. The water jet is used as an alternative for the parts which are not resistive to heat produced by different CNC cutting operations.
3. Plasma Cutters
Plasma cutters are employed to cut the hard parts with plasma torch. In order to produce the required heat and velocity, plasma torch is generally produced by the combination of electrical arcs and compressed air. Plasma cutter is used to cut hard material such as metal, plastics etc.
4. Electric Discharge Machining
EDM is another CNC operation that can be used to mold the raw material into the desired shape with the use of an electric spark. The section of the workpieces can be removed by current discharge between the two electrodes. Wire EDM and Sinker EDM are the two operations that can be performed by CNC machines.
Introduction of Artificial Intelligence in CNC
AI (Artificial Intelligence) is basically the system or operation of algorithms that are optimized automatically as they undergo some processes. The field of manufacturing is witnessing revolutionary changes after the introduction of Artificial Intelligence in the CNC machines improving its performance.
Artificial Intelligence reduces machine downtime. As the machine runs, it develops faults which sometimes are difficult to be detected thus reducing the productivity depending upon the industrial scale. With the introduction of AI in CNC machines, the machine will be able to self-diagnose the fault with the help of AI software saving many hours of machine downtime. Moreover, the introduction of AI in CNC will also aid in quality control by maintaining the consistency of the output. The output will be continually monitored and checked with automatic adjustments made in order to produce consistent products. This will have an impact on the cost and efficiency with higher accuracy and less wastage of the raw material.
Advantages of CNC Machining
There are many advantages of CNC machining over the conventional manufacturing process. Therefore mostly manufacturers are employing this rapid manufacturing technique in order to obtain precise and accurate parts in lesser time. Following are some of the advantages of CNC machining:
One of the most significant advantages of CNC machining is speed over conventional machining. This advantage is particularly apparent when mass production of components take place as the computer can repeat the programme as many times without any interruptions.
2. Precision and Accuracy
Accuracy is another reason of favor of CNC machining over conventional machining. The best machine settings provide tolerances of 0.001” due to the autonomous nature of the machine. Such fine tolerances are demanded in the automotive industry where the failure of any critical component can result in serious consequences especially in self-driving cars.
The job of the CNC machine can be repeated without any discrepancy so the parts produced are identical and accurate. So this technology is particularly useful in mass production where error-free identical parts can be reproduced.
CNC machining has wide applications in production of industrial and domestic products. CNC operations are mostly used in metal removal industries such as aerospace industries, automotive industries etc. where these machines are used to remove the excess material from the raw material in order to obtain the desired product. CNC machines are also used in these industries in order to create parts with complex geometries.
Moreover, CNCs can be used in metal fabrication industries where various operations are performed on a thin metal sheet such as cutting, drilling, boring etc. with accuracy. These machines are also used to produce various tiny components of motherboards and circuits which can only be produced with such accuracy with the help of CNC machining. These machines are also used to produce firearms and in EDM applications.
CNC machining is one of the most used and accurate rapid prototyping technique being employed by the manufacturers these days. CNC prototyping, this technique has an advantage over conventional manufacturing techniques in terms of speed, accuracy, and repeatability making it a favorable option for different industries such as automobile industry, aerospace industry and firearms industry etc.