CNC (Computer Numerical Control) machines are widely used in modern manufacturing. These are computer-controlled tools designed to make precise movements in repetitive patterns. They were introduced to the industry in the 1940s and 1950s. As high-precision machines, they are used in various machining operations. Although CNC machining is very similar to 3D printing, the main differences are high precision, advanced speed, and cost. CNC machines are generally better for more precise, efficient, and high-quality projects. There are different types of CNC tools, and manufacturers mostly use them for projects that require high precision and accuracy. Hence it is important to choose the right machine for your project. However, before we discuss these tools, let’s take a closer look at the different types of CNC.
Types of CNC cutting machines for plastics and other materials
There are basically five broad categories of CNC machine tools, depending on the type of machine tool, precision and the nature of the project. These are:
- CNC milling machine
This is the most popular type on the market. A specific program in alphanumeric form is translated into a CNC (computer numerical control) milling machine. These machining operations use a programming language called G-code. Once programmed, a rotary cutting tool cuts the sheet metal into various shapes and sizes. Unlike other manually operated milling machines, CNC routing offers much greater precision.
- CNC router
Like most hand-operated routers, CNC equivalents can cut wood, plastic, steel, aluminum, foam and composites. However, you can cut more prototype models and advanced material shapes with a CNC. As with a CNC router, the Router works with digital computer controllers to produce more parts in less time, increasing productivity. Typically, industrial CNC routers have 3-axis machines, but technical and highly complex machining operations use 4-axis, 5-axis, and even 6-axis machines.
- CNC lathe
Using a different programming language, these machines can make more precise cuts. These are rotary machines that precisely cut three-dimensionally shapes and form materials. These machines are ideal for producing spherical or cylindrical workpieces.
- Plasma cutting machine
CNC plasma cutting machines are used for cutting heavy metals such as steel. They work on converting gas into plasma blown at high speed through the cutter. Properly heated plasma will melt almost any metal being cut by the machine, and the high pressure obtained in the process of using the cutter blows away any metal fragments at the cutting point.
- EDM machine
EDM machines can be virtual machines or wire machines. They use electrical discharge to cut sheet metal. Because of this, they create materials of specific shapes and sizes. In addition to these five types, there are other types of CNC machine tools on the market. With the advent of these machines, manufacturing has become more accessible, as more precise and accurate designs can be created in the shortest possible time.
Cutting tools have existed since ancient times. They are one of the oldest inventions in human history, and the ones we use today have radically changed. They involve the use of different types of saws. Originally we built them out of stone, so today’s metal tools have gained great value in manufacturing. Although all cutting tools serve the same purpose, cutting material uses are highly diverse.
Basically, for a cutting tool to be effective, it must meet the right criteria:
- It must be 30% to 50% harder than the material it is working with.
- It has a high thermal conductivity.
- Has a low coefficient of friction.
- Chemically inert and stable.
In practice, CNC tools perform a variety of cutting operations. Before considering which one to use for a particular operation, you need to know what plastics the manufacturer used to make the tool. Based on this material, we divide cutting tools into:
Carbon steel tools
These cutting tools are inexpensive and designed primarily for low-speed operation. They have a carbon content of 0.6 – 1.5% and small amounts of manganese and silicon. They are mainly used in twist drills, forming tools, cutters, and lathes.
High-speed steel (HSS)
It consists of high-carbon steel and an appropriate amount of alloying elements such as chromium, tungsten, and molybdenum. This combination increases hardness, wear resistance, and strength. This provides higher removal rates for metals and other materials.
These chemically inert tools resist corrosion and are up to ten times faster than HSS. Typically, the ceramic material is created from aluminum oxide and silicon nitride. Projects requiring the highest quality finishing operations often use this material.
Designed for high-speed operation, these carbide tools are extremely hard and can withstand temperatures up to 1,000 degrees Celsius. They are usually formed from tantalum, titanium, and tungsten. They are also used in operations that require a high quality surface finish.
CNC cutting tools
CNC cutting tools are available in a variety of shapes and sizes for various milling and turning operations. In addition to this, the workpiece must be machined with the right software and cutters. Some CNC cutters are:
Shank cutter – A rotary cutting tool that can be used to remove material. Although similar to drills, burrs are used for more general machining operations. Unlike drills, which cut into material axially, burrs are lateral tools that can cut in any direction. Due to their design, some burrs cannot cut fabric axially. In general, burrs have different types of end mills, each depending on the desired end product.
The different types of end mills are:
- Ball milling cutters: ideal for working with 3D contours, ball milling cutters have a rounded tip for perfect curved surfaces.
- V-groove cutters: these tools make a V-shaped cut. V-grooves can be 90o or 60o, depending on the angle of recess required by the material. Although they are commonly used for engraving marks on materials, they are ideal for projects requiring a sharp edge.
- Straight Groove Cylindrical End Mills: these CNC cutting tools are general purpose tools that provide excellent edge quality.
- Downcut and Upcut milling cutters: these spiral tools produce a smooth surface finish by moving chip residue downward or a rough surface finish by moving residue up and away from the designated area.
- The basic design of a spiral face milling cutter includes a groove (spiral groove), a cutting edge (tooth), a diameter, a shank, a cutting length and the tool’s overall length.
- Before proceeding to the machine, remember the need to design the cut in advance with the material’s thermal stability.
Below are the drills and cutters that are used for CNC cutting
Twist drills: These CNC rotary cutters have two grooves and two cutting edges. Due to their unique design, coolant quickly reaches the cutting point. Manufacturers often use these cutting tools to reduce production costs and perform operations with a top-notch finish. A twist drill consists of three main parts: shank, body, and tip.
Flying shear blade: These single-edged blades on milling machines, are general-purpose, provide excellent surface finish. The CNC cutter passes through the material’s surface, rotating clockwise, making the surface of the material smooth and flat. They are designed for CNC engineers looking for an excellent, precise finish.
Cutting coolants and cutting fluids
Usually not used in CNC cutting tools. Coolants and cutting fluids remove chips from the cutting area. They also provide additional benefits such as:
- They reduce thermal deformation of the workpiece.
- They improve tool life.
- They improve surface finish.
- Tool holders typically hold CNC cutting tools in place before they are installed on the CNC machine.
Why choose the right CNC tool?
Machining plays a vital role in the quality of your project. CNC cutting differs from traditional cutting techniques in many ways. Although CNC machines are expensive to buy, the wide spectrum of the use of computer-controlled machines must be considered. In fact, the quality of your project depends on the cutting tool used. The industrial world is highly competitive, and manufacturers and end users on the road to success must create the highest quality products through proper planning and precision cutting. Since cutters are the backbone of professional design, special attention should be paid to those small details that can improve your design. Higher productivity, high precision, accuracy, and machining efficiency are the driving forces required to produce first-class products. You can quickly achieve these advantages of CNC cutting with the right cutting tools, and a solid understanding of CNC cutting tools is the first step to success in a competitive industry.