When we talk about 3D Printing, it is an additive manufacturing process that adding material layer by layer by a 3D printer. What about subtractive manufacturing, if there are any? Definitely. CNC Machining is the most typical subtractive manufacturing and a highly versatile and robust method to manufacture metal and plastic parts. The machining tools of the CNC machine is moving and cutting materials under computer control automatically, producing parts with extreme precision and mechanical properties. In this article, we will introduce the basic principles of CNC Machining, CNC machines, and advantages and limitations of the technology.

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Part 1. What is CNC Machining?

CNC stands for Computer Numerical Control. CNC Machining is a subtractive manufacturing process that controlled by pre-programmed computer software. And the software leads the movement of CNC machine and remove materials of the parts. Complex machinery was controlled through the whole process, including grinders, mills, lathes, and CNC routers. These machining tools are used to shape, cut, and create various prototypes of which materials can be metal, plastics, and even wood.

CNC Machining plays vital role in modern manufacturing industry for one major reason that it produces high quality and reliable parts for small to medium batch production. To satisfy manufacturing needs and deliver ideal solutions to manufacture parts with different geometries, there are two main types of CNC Machining systems, CNC Milling and CNC Turing. Let's learn more about these two types step by step in the following sectors.

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Part 2. How does CNC Milling work?

CNC Milling is the most common and popular machine in CNC manufacturing. CNC Milling machines utilize rotary cutters to remove material from a part mounted on the machine bed. There are different types of CNC Milling systems, the most common type is 3-axis CNC machine. 3-aixs means the system has 3 linear degrees (the X, Y, Z axes) to produce parts. While the advanced one is 5-axis CNC machine, which owns 5 degrees of machining freedom and is suitable for creating parts with highly complex geometric geometries. Besides, 5-aixs CNC Machining is ideal for simplifying manufacturing steps. Let's take a look at how CNC Milling system produces custom part form a CAD model.

1. Like 3D Printing needs slicer software to covert the STL file so that 3D printers can read and understand each layer data of the model, the first step for CNC Milling is to convert the CAD file into a language that the machine can work with, that's G-code.

2. The operator will place the material that is cut to a specific size on the machine bed. Normally, the piece of the material is always called the blank or workpiece. Then it is time to mount the workpiece on the machined bed or by a vice.

3. As the computer controls the CNC cutting tools to move to the pre-set coordinates, so precise positioning and alignment of the workpiece is significant to manufacture high-accuracy parts. Special metrology tools, probes, for instance, are ideal solutions for this step.

4. Then, the workpiece is ready for machining. The machine uses professional cutting tools and rotating the at high speeds to remove material from the workpiece. However, at the very first steps, the machine removes at a relatively low speed and accuracy to gain an approximate geometry.

5. Sometimes, the model is not being to achieve full features by single setup from the cutting tools, to flip the workpiece is necessary.

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Part 3. How does CNC Turing work?

CNC Turning machines, or we call CNC lathes remove material from workpiece mounted on rotary chucks by utilizing stationary cutting tools, which is an ideal solution to producing parts that are symmetrical about a central axis. Therefore, CNC lathes usually make cylindrical parts. But if CNC Turning systems equipped with CNC Milling tools, non-cylindrical parts can be manufactured as well. It can be a versatile solution for manufacturing. Combining high productivity and efficiency of CNC Turning with machining capabilities of CNC Milling, the system is being able to manufacture parts in a variety of geometries with rotational symmetry. Let's see how does CNC lathes work exactly.

1. The first step before machining as same as CNC Milling, that is to generate G-code from a CAD model and import the G-code file in the machine control system.

2. By mounting the workpiece, the lathe is rotating at a high speed while the stationary cutting tool following the line to remove materials from the workpiece.

3. If holes are existed in the original design, holes can be created by internal cutting tools and center drill along the center axis of the part.

4. Like CNC Milling, if operate needs to flip the part, the machining process will be repeated.

Both CNC Milling and Turning need to deburr the machined parts to remove small defects manually. And the parts may send for post-processing for special surface finishes or colors, etc.

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Part 4. Common Cutting Tools of CNC Machining

There are a wide range of cutting tools of CNC Machining in order to manufacture parts with diverse geometries. Let's introduce some common cutting tools in CNC Milling process. There are flat head, bull, head, ball head, drills, threading taps, face milling cutters, and slot cutters. Flat head, bull, head, and ball head are tools to machine groves, cavities, slots, and other vertical walls. Slot cutters are used to cut T-slots other undercuts by removing material from the sides of a vertical wall. Drill is the ideal tool to create holes efficiently. Threading taps are used to create threaded holes. If you need to remove materials from the large and flat surface, face milling cutters is what you need.

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Part 5. Advantages and Disadvantages of CNC Machining

Pros

1. CNC Machining produces parts with very tight tolerance, which means the technology can create parts with extreme high accuracy.

2. Most materials that can be applied in CNC manufacturing are tend to have good mechanical properties, making the parts are high-quality and suitable for high-end applications, aerospace, engineering, and automobile, etc.

3. CNC Machining is the most cost-effective manufacturing process to produce metal parts from single prototypes to even up to hundreds of batch production.

4. The technology tends to create final parts with no defects, and the final parts can be used directly in applications.

5. CNC Machining needs less workers to operate as most of the process is automatically, which save personnel cost and enhance personnel safety.

Cons

1. The start-up and installation costs are high because CNC machines can be very expensive and it needs professional staff to operate the machine.

2. It takes time to train staff to operate the machines.

3. Lead time of CNC machined parts are relative longer than 3D printed parts.

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Part 6. CNC Machining Services at Wenext

With massive in-house manufacturing capabilities, Wenext provides dedicated CNC Machining services on demand. We offer CNC Milling and CNC Turning to meet diverse needs of producing parts with various complicated geometries. Besides, parts can achieve different surface finishes, such as polishing, plating, sand-blasting, coloring, laser etching, heat treatment, anodizing, etc. Upload your CAD files directly on our instant quoting engine, and get a quote seamlessly. Before delivering the CNC machined parts in a short lead time, we will go through strict inspection for each part, ensuring that our customers will receive the flawless parts with accurate specifications. For more information, send an email to hello@wenext.com.