Computer numerical machining is a popular manufacturing method because of its ability to support mass production of parts. Technological advancements in CNC machining have made it possible to produce parts with complex geometry by using CNC machine.
What is CNC?
CNC is an abbreviation for Computer Numerical Control. CNC machining is a subtractive manufacturing technique used to make a variety of parts and products with accuracy and repeatability. This process makes products for a range of industries, such as automotive, aviation, pharmaceutical, and electronics. By using CNC machines, manufacturers can make quality products from various materials such as composites, metals, and plastics.
Components of CNC Machine
Input Devices
Input devices provide a means by which the CNC program is loaded into a machine. These include a keyboard, wireless communication, and a USB flash drive. With the keyboard, you can input the G-code commands directly. The USB flash drive is used for transferring the program from a computer to a CNC machine.
Machine Control Unit
This is a combo of software programs and electronic hardware that interprets the G-code. It translates the G-code into instructions, which are executed by the machine to carry out the required machining processes. As a result, this makes it a vital CNC machine component.
This component also interprets data from the feedback sensors. In this way, it ensures the cutting tool is in an appropriate position once the movement is complete. In addition, this component controls the coolant activation and tool changers.
Tools
Commonly called machine tools, these refer to tools that perform any given process on the workpiece. Depending on your CNC machine, you can have a range of machine tools. For instance, CNC milling machines require spinning tools, whereas CNC lathes have stationary tools.
There are also 5-axis CNC machines that move both the workpiece and machine tool. As a result, these machines can produce complex parts. Depending on the type of machine, there are tool libraries, which are basically machine racks to keep your tools.
Feedback System
Although the driving system provides precision movements, there is a need for a closed-loop control system. This ensures the workpiece is moved to the required position and adjusts it accordingly. This is known as the feedback system.
Display Unit
Display UnitIdeally, this is a monitor that displays vital information to the CNC machine operator. There is a wide range of screens ranging from large HD screens to small ones displaying only the necessary information. You should note that the display unit plays a critical role in the way the operator uses the CNC machine. This is because it helps the user change machine parameters and input G-code.
Bed
The bed provides a place for mounting raw materials. A range of jigs are used to hold the workpiece securely. Usually, the bed has holes and slots where jigs are attached. Modern 5-axis CNC machines have beds both on the x-axis and y-axis.
Headstock
This component is found in CNC lathes. It contains the gears, main drive, and bearings. In most cases, it is enclosed and can only be accessed by removing inspection panels.
Tailstock
Just like the headstock, this is also a component of the CNC lathe. This component helps in supporting the workpiece, making it important for cutting workpieces such as shafts and screws.
How CNC Machine Works
Although there are a variety of CNC machines, their primary mode of operation is the same: a program converts the 3D model into instructions (G-code) for the CNC to interpret and create the part. After inputting the G-code and workpiece, the machine does not need any human intervention. These steps make up the CNC machining process.
Designing 3D Model
The process starts by creating a 3D CAD model following design principles that suit DFM’s philosophy. This is necessary to ensure the product will be manufactured efficiently on the CNC machine.
Conversion of CAD Files
After creating the CAD file, you need to export it to the CAM program. This will then convert the model into instructions that are interpreted by the CNC. As a result, a G-code file is generated.
CNC Machine Preparation
The operator prepares the CNC machine by setting up the workpiece and checking the availability of the required tooling. These machines have tool libraries and automatic tool changes. This means they can select the required tools automatically.
Machining Operation
Once the workpiece is placed correctly, machining starts. The machine selects the required tool and starts to cut the workpiece as per instructions.
Types of CNC Machines
Although there are many types of CNC machines, they are either CNC lathes or CNC mills.
CNC Lathe
This CNC machining process, in this case, cuts the workpiece by rotating it. Since it has fewer axes as compared to mills, it is more compact and smaller. The mode of operation involves cutting chunks from the rotating workpiece with the stationary cutting tool.
CNC Mills
These are the most common CNC machines and support a range of operations. Some of the operations include boring, slotting, facing, and chamfering. To support these processes, the machine uses multiple cutting tools. The main difference with CNC lathes is that CNC mills rotate and translate the cutting tool. This allows for the machining of up to five faces of the workpiece.
The common types are 3-axis and 5-axis CNC milling machines. With the 5-axis CNC, you can create complex parts.
Advantages of CNC
CNC machining continues to revolutionize manufacturing. This is because it minimizes manual work and delivers parts with desired levels of accuracy and consistency. These are some of the advantages of CNC machining:
High Production Speed
CNC machining allows you to increase your production as it gets rid of the limitations of human labor. As a result, it is suitable for mass production.
Consistency
With CNC machining, you can create parts that look and function the same. This is because there is no human error. With traditional manufacturing practices such as fabrication, you can have product rejections because of errors. This can be a waste of resources and time.
Cost
Automation, speed, precision, and efficiency of CNC machines minimize manufacturing costs. Also, automation reduces downtime and human labor required. As a result, you can produce more parts at a lower cost, giving you a competitive advantage over other manufacturers.
Material Versatility
The good thing about CNC machining is that you can manufacture parts from a wide range of materials, such as plastic, wood, metals, and alloys.
Limitations of CNC
Although CNC machining is an efficient and precise machining technique for making complex components, it has its share of limitations. These include:
- Tool capabilities – it is difficult for the tool to cut intricate features
- Tool shape – The shape of the tool impacts the final shape and cut
- Tool stiffness – Tool deflection is a common occurrence, especially when working with tight tolerances
- Workpiece stiffness – Some materials have superior mechanical properties, making machining quite challenging.
- Workholding – Workpiece movement during machining can result in inconsistent tolerances
CNC Size Considerations
When creating a part, you have to pay attention to these guidelines:
- Machine type – Make sure you assess the strengths and limitations of the type of CNC machine.
- Tool restrictions – Always consider the tool’s geometry, material, length, and whether it is a specialized tool.
- Design guidelines – You should take into account inner edges, thin walls, holes, and other features such as threads and tapped corners.
Applications of CNC
These are some of the industries where CNC machining is widely used:
- Automotive – CNC machining helps manufacture engines, frames, and other parts for vehicles, trains, and motorcycles.
- Metal fabrication
- Research and Development – Used in creating prototypes
- Electronics – Making of frames for appliances
- Automation – Manufacture of robot components such as robotic arms
- Medical – Making of parts and components for medical equipment such as MRI machines
Conclusion
CNC machining remains one of the top modern manufacturing processes that are widely used in various industries. Even with basic raw materials, CNC technology can turn them into mind-blowing products. Sourcing your CNC parts from reputable companies such as Sunrise Metal is key to achieving the needs of your project.