CNC Milling: Definition, Process, Benefits & Applications

The precision of CNC milling technology is unmatched, allowing for intricate designs and high-quality finishes that meet rigorous industry standards.

CNC milling is one of the most vital processes, applied in the manufacturing of many products that are in use today including smartphones to jet engines. It is regarded as a reliable and versatile machine that can be used for small parts production as well as for large-scale production of plastics and metals. Now let us look at some of the advantages of cnc milling, and uses of the CNC milling process.

What is CNC Milling?

CNC Milling

CNC milling is a material removal process in which the parts are machined with the aid of a computer numerical control system. CNC milling is a process of cutting out parts from a solid block with the help of machines that are computer-controlled and that are used to cut through metals, plastics, wood, and other materials to produce very complex parts. This guide looks at how CNC milling machines work, how they differ from other milling machines, and how one can design parts for CNC milling.

How do CNC Milling Machines Operate?

The CNC milling process involves a series of steps to transform a digital design into a physical component: 

1. Design Creation: Begin with creating a part with the help of CAD software like Autodesk Fusion 360. This design is the real design that is used in the real machining of the product. 
2. Generate Instructions: Employ CAM software in a way that will convert the CAD model into a form that the CNC machine will understand. This leads to G-code, which is a set of codes that describe the position and the function of the machine. 
3. Machine Setup: Secure the material even more rigid to the bed of the milling machine and control it with the help of the above-mentioned tools. Place the spindle and adjust the machine as per the requirement of the work that has to be done.
4. Milling Operation: The first operation of the CNC milling is that the G-code has to be fed into the CNC milling machine. The cutting tool of the machine will then swivel and trim the block to the desired shape and thickness.

CNC Milling as Compared to CNC Turning

CNC milling and CNC turning are both subcategories of CNC machining but they are used in different processes: 

• CNC Turning: CNC Turning is employed for cylindrical or conical surfaces with the help of a lathe machine which is used to hold the workpiece and rotate it. It is done by coming into contact with a single-point cutting tool for cutting, drilling, and threading operations. 
• CNC Milling: This technique involves the use of a milling machine to make flat surfaces and other shapes through the use of a multi-point cutting tool. It is also able to perform intermittent cutting operations and several operations at one time.

Types of CNC Milling Machines

• 3-Axis Milling Machines: These machines use a cutting tool that is controlled in three axes; the X, Y, and the Z axis to create simple geometrical shapes. It is cheap and suitable for a low variety of part types. 
• 4-Axis Milling Machines: These machines also have three straight movements and the fourth one known as the A-axis is a rotation movement to turn the workpiece. This feature is used in the machining of parts with cylindrical surfaces or side cuts on the part.
• 5-Axis Milling Machines: These advanced instruments give motion in three straight directions and two other circular directions. This capability allows the manufacturing of difficult parts in one clamping operation; they are ideal for complex shapes in aerospace, medical, and high-performance parts.

CNC Milling Operations

CNC milling comprises several processes that are suited for a certain application and result. Here’s a detailed look at common milling operations: 

Face Milling:

Face Milling

In face milling the cutter is referred to as a face milling cutter and it is mounted in such a way that it is perpendicular to the surface of the workpiece. It has several cutting edges which enable one to produce a smooth and good finish on the workpiece. Face milling is widely used in the manufacturing processes for making flat planes and for obtaining a high surface finish.

Plain Milling:

Plain Milling

Plain milling is also known as column and knee milling in which the cutter is mounted horizontally for the workpiece. This process is applied in the milling of flat and horizontal planes only. To obtain the required cut the table can be fed in longitudinal direction, crosswise, or in the vertical direction. Plain milling is most suitable where flat surfaces of the workpiece are to be milled. 

Angular Milling:

Angular Milling

Angular milling is employed in cutting flat surfaces in a way that they are inclined to the workpiece. Angular milling is different from plain milling in that the tools are mounted at a certain angle to produce the desired angle. In general, there are two kinds of angular milling cutters:  

• Single-Angle Cutters: These have teeth on the angular face and large flat sides appropriate for such angles as 45° or 60°. 
• Double-Angle Cutters: These have V-shaped teeth with conical faces and are used in cutting angles of 45°, 60°, and 90°. 

Form Milling: 

Form milling is employed in making features on a workpiece that may be curved or of irregular cross-section. In form milling, the type of cutters to be used are those that will suit the contour formed in the milling operation. This one is relatively slower than other milling methods because of the cutting action involved, however, it is important in the production of parts with complicated shapes such as concave or convex. 

Slot Milling:

Slot Milling

Slot milling is the process of making slots or grooves in the workpiece with a cutter that is narrower than the slot. This technique is most suitable in the fabrication of slots’ key ways or channels with a high degree of accuracy. 

Side Milling: 

Side milling is employed in cutting of vertical plane on a work piece. This is done by using a cutter to generate flat vertical surfaces. The depth control is done through the vertical feed screw of the milling machine and is adjusted according to the depth required. 

Gang Milling: 

Gang milling is an operation in which several cutters are mounted on a spindle in such a way that they can perform horizontal milling simultaneously on the surface. The method is also economical in the sense that several operations can be done on the workpiece in a shorter time.

CNC Milling Machines Parts

Precision CNC Milled Part

A milling machine has the following parts that are very vital in the operation of the machine; Here’s an overview of the main features:  

• Knee: The knee is an adjustable unit that is firmly secured to the column. It supports the saddle on which the operator sits and the worktable on which materials are placed at the same time. During the movement along the Z-axis, the knee also allows precise control of the height of the worktable and the position of the workpiece. 
• Column: The column is the largest and the strongest of all the parts of the milling machine and it is the most rigid of all the parts. It assists and enhances the machine in the sense that it embraces other parts and makes the machine rigid when in operation. 
• Saddle: The saddle is placed above the knee and below the worktable and it slides in the direction of the spindle of the machine. This movement enables the correct location of the workpiece and makes it possible to make horizontal adjustments during milling. 
• Worktable: The worktable is the table on which the workpiece is positioned and clamped for operations to be carried out on it. It is placed on the saddle and can normally be shifted in the vertical as well as in the transverse direction depending on the design of the machine. This adjustability is useful in several milling operations because the workpiece can be well-positioned and oriented in the best way possible. 
• Spindle: It is a rotating bar that supports and operates the machine tool or arbor of the machine. It is an electrically operated machine that causes the cutting tool to mill through rotation at high speeds to remove material from the workpiece. 
• Arbor: It is mainly used in horizontal milling machines; it is fitted in the spindle where it acts as a shaft. It allows the different milling tools to be attached and employed, which creates versatility in the type of cuts and shapes that can be produced. 
• Ram: In the vertical milling machines the ram is positioned on the top of the column and contains the spindle. It can be shifted to another place to enable the spindle to be placed at another place which makes the milling process more flexible and accurate.
• Machine Tool: The cutting tool is the cutting element and it is fixed on the spindle of the machine tool. It does the milling by cutting away material from the workpiece. Machining tools can be divided into a great many groups based on the kind of cut and material that is being worked on.

Choosing The Right CNC Milling Materials

Choosing the right material to be used in CNC milling is very important so that the work being done will produce the right results. Here are key factors to consider: 

Functionality: 

Select materials that are appropriate for the part that the material is to be employed in. For instance, stainless steel has higher corrosion resistance than carbon steel and therefore is preferred in areas where corrosion is likely to occur. 

Stress Load: 

The strength of the material is the stress level at which the material is unable to deform or crack. Where there will be high stress, it is advised to use high-stability and strength materials. 

Dimensional Tolerance: 

Conventional tolerance management ensures that the parts will fit in the right place and perform as expected. It should be possible to achieve the right degree of accuracy in the materials in a manner that enables the assembly and running of the equipment. 

Operating Temperature: 

The material used should not melt at the working temperature of the CNC milling machine and therefore the material should have a higher melting point than the working temperature of the CNC milling machine. This is done to avoid the deformation or damage of the parts during the machining, which is to be done on them. 

Cost: 

Price is one of the most crucial aspects that define the type of material that is to be used. This means that you should be able to vary the budget to the mechanical properties of the material to achieve the best performance at the least cost.

Common materials for CNC milling include

• Metals: Aluminium, stainless steel, tool steel, mild steel, brass, copper. 
• Plastics: ABS, polycarbonate, nylon.
• Others: Ceramics, composites, phenolics.

Pros and Cons of CNC Milling

Advantages: 

1. Precision and Accuracy: CNC milling machines are precise and can be used on a part with a tolerance level of 0. 0004 inches. CNC milling is an automatic process and as such there are no interferences from the operators and this makes the results accurate. 
2. Speed and Efficiency: CNC milling is faster as it uses a fly cutter than manual milling because it does not have time to change the tools and can continue working for several hours. In its operations, CNC milling is efficient and thus reduces the time taken to create a product and time to market. 
3. Material Versatility: CNC milling can be done on all forms of material including milling metal, plastic milling, and other composites. For this reason, it can be applied in a variety of applications from simple parts to more complex ones. 

Disadvantages: 

1. Material Waste: CNC milling is a subtractive process, this is in the sense that during the process of milling, the material is cut or shaved off to form the product. This is often the case and leads to more wastage than the additive manufacturing processes such as the 3D printing processes.
2. Maintenance Requirements: CNC machines are however sensitive and need to be maintained often so that they can function to the optimum. The costs and problems of maintenance may be high where the equipment is complex, especially in terms of design.

Applications of CNC Milling 

Because of the high precision and the ability to work with various materials that are linked to CNC milling, it can be applied in many fields: 

Aerospace: 

In the aerospace industry, CNC milling is applied in the manufacturing of parts from metals such as titanium and aluminum. CNC milling is particularly suitable in the production of aerospace components because of the high precision that is expected of the parts. 

Automotive: 

Some of the areas where car makers use CNC milling include the making of engine parts, suspension parts, and interior panels. The precision and the rate at which the CNC milling is done are very important to create high-quality automobile parts. 

Agriculture: 

CNC milling is used in the agricultural sector in the manufacture of some parts such as gears, shafts, and fasteners among others. It is used for the production of a large number of standardized products and also for the production of small special parts for tractors. 

Medical: 

Medical industries are also in a position to benefit from the accuracy of CNC milling in the manufacturing of prosthetics, implants, and other health-related products. CNC milling is crucial in advanced medical solutions since it is possible to create complex and individual parts.  

CNC Milling – Cost Drivers 

The cnc milling costs are influenced by several factors:

Design: 

Design is not cheap to come up with a CAD model, used in CNC milling. Among the costs that are likely to be incurred include the cost of designing the part, the cost of programming the machine, and the cost of checking the design. Most of the CNC milling services include such costs in their bids. 

Complexity: 

As the designs become more complicated, more sophisticated instruments are needed, and the time taken to develop them is longer than the time taken to develop simple designs, and therefore they are expensive. Higher complexity also requires better technology and the operating costs are also high for sophisticated cnc milling parts. 

Production Volume: 

This is so because higher production volumes are cheaper to produce due to factors such as economies of scale. The cost per part is lower with large volumes than with small volumes because of the high setup and processing time.

CNC Milling Machines 

3-Axis Milling Machines are the most basic type and move along three axes: X, Y, and Z These are basic shapes that are very useful for basic cutting designs. They are charged at forty US dollars per hour in Europe.

• 4-axis Milling Machines also have an additional axis that can be utilized to help turn the workpiece to make additional precise cuts. They ranged from $75 to $120 per hour in Europe but some services provided them at lower prices.  
• 5-Axis Milling Machines are of a type that has three linear axes and two rotary axes. This makes it possible to produce very intricate and fine components and subassemblies as well as those that are very large and heavy. It may range from $75 per hour and can reach $120 per hour, although some services are even cheaper. 

Material Costs 

Plastics are more manageable and cost-effective in most of the cases. Some of the most popular types are ABS, Delrin, and Nylon 6 and the cost of these blocks is from 17 to 30 US dollars. 

Metals are slightly costly and are offered in Aluminum 6061, Aluminum 7075, Stainless Steel 304, and others. It is possible to receive these materials in the form of a block for a price ranging between $25 and $90. 

Surface Finishing 

Other treatments like anodizing and powder coating improve the aesthetic value and the service life of the parts. All these processes are part of the total cost of CNC milling. 

Additional Costs 

Transportation cost depends on the distance, the level of urgency, and the weight of the material that is to be transported. This can impact the overall cost of your CNC milling project.

Prolean Tech: Best CNC Milling Solutions Provider

Before a part is sent to be milled by CNC, certain rules of DFM must be adhered to make the part machinable. At Prolean Tech, we make it easier for you to do so. When registering with us, you can receive an initial DFM analysis and a free quote in a short time. Our team of CNC milling specialists will assist you in getting the best out of your design to achieve the accuracy and quality of the parts that you require. So, hand over your milling project to trust Prolean’s cnc milling service, and see your ideas come to life.

Key Highlights of Prolean’s CNC Milling Services

• Precision First: Every project, regardless of scale, is executed with unparalleled accuracy.
• Material Versatility: From metals and alloys to plastics and composites, Prolean handles it all.
• Advanced Machinery: Prolean stays ahead of the curve with state-of-the-art CNC equipment.
• Skilled Artisans: A team of experienced professionals ensures every detail is perfect.
• End-to-End Solutions: From design consultation to final product delivery, Prolean has you covered.
• Customer-centric Approach: Bespoke solutions tailored to individual project needs.

Summing Up

CNC milling is an innovation that has changed the manufacturing sector. This method offers precision with versatility in creating intricate designs across various materials. It brings numerous benefits for vast applications in diverse industries. However, the right material, tools, parameters, and expertise are essential to obtain optimum results. 

As industries evolve and the demand for precision and efficiency rises, CNC milling continues to stand out as the preferred choice for many. Indeed, when one reflects on the question, “What is CNC milling?”, it’s clear that it’s not just a process but the Present and future of manufacturing.

FAQs

What is CNC milling?

CNC milling is a  computer-controlled method to carve and shape materials.

How does CNC milling differ from traditional milling?

CNC milling employs computerized instructions, ensuring higher precision and automation.

Which industries predominantly use CNC milling?

CNC milling has diverse applications across the industries, such as Aerospace, automotive, healthcare, and many more.

What materials can be used in CNC milling?

CNC milling can process metals, plastics, ceramics, and even some composites.

Why choose Prolean’s Metal CNC Milling services?

Prolean ensures top-notch quality, precision, and expertise in metal milling.

Can CNC milling handle complex designs?

Absolutely, especially with advanced 4-axis and 5-axis machines.