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Everything You Should Know About Complex CNC Machining!

The industrialization has brought a massive advancement in the technology world. CNC machining is one of those advancements.

It offers the most convenient mechanism used in subtractive manufacturing technology.

In CNC machining, various cutting machines help extract the parts of solid metal or plastic. As a result, it enables you to create simple and complex parts.

This article will examine the setup of CNC machines for complex parts. You will have an overview of CNC technology’s fundamental principles.

So, let’s start!

5 axis machining

Why Should You Use CNC Machining for Creating Complex Parts?

CNC machined parts can often vary in complexity. It ranges from simple planar features to demanding, complex curved geometries. Thus, it’s vital to choose the correct CNC machine.

Different types of CNC machines with different features are available in the market. But, a very few of them can be beneficial for complex parts.

china cnc machining complex impeller min

The part’s complexity will determine the type of CNC machine you can use. It includes a CNC lathe, a three-axis CNC machine, or a five-axis machine.

Depending on the part geometry, complexity, and dimensions, you can choose the machine. Moreover, you can also consider tolerances, end-use of the product, and material.

A more complex part will need more consideration. That includes its design, specific dimensions, and requirements.

So, design engineers should always, where possible, work to create simple, easy-to-produce parts. The simpler the design of your part, the easier it will be to manufacture.

Mechanical designers often create designs that have fewer components while offering performance. It can drive costs down while also ensuring efficiency and higher output.

A) 3-axis

The 3-axis machining comes in two types: CNC milling and CNC turning.

Both methods let the tool move in three (x, y, and z) axes close to a fixed workpiece. Both processes remove material from a fixed workplace using different cutting techniques.

Also, it is a subtractive machining process. It uses a cutting tool rotating at high speed to achieve better accuracy and a smooth finish.

The tool features a spindle that can move along three linear axes. Besides, there are two rotational axes.

3 axis machining

CNC milling is the most used CNC process. It can help you produce the most simple geometries. Besides, the start-up machining costs are also low with the ease of setup and operation.

But, 3-axis CNC milling has some limitations when geometries become more complex.

As you can notice, there are only three axes to work within this machine. Besides, it can perform two rotational motions only.

Thus, there may be areas the cutting tools will not be able to reach. Thus, there are design restrictions for 3-axis CNC milling.

Next, we will discuss five-axis machining. It will help you figure out the main difference between the two machines.

B) 5-axis

We call it 5-axis indexed milling, multi-axis machining, or 3 + 2 machinings. It works by rotating the workpiece around the B and C axis to the required position. The workpiece then remains stationary.

5 axis machining

The tool makes the desired cuts by moving its three linear axes. Both axes will re-orientate the workpiece when changing the cutting location.

The main benefit of this method is that it eliminates the need to reposition the workpiece. It reduces the manufacturing time. Moreover, it increases the accuracy of parts with complex geometries.

5-axis continuous CNC milling machines are like 5-axis CNC milling machines. Here, the workpiece rotates around two axes (B and C) during operations. The workpiece and cutting tool can use a rotation axis to move in five different axes.

It produces smooth contoured surfaces with high accuracy. That makes this method popular in the aerospace industry.

But this method needs expensive machinery and high-level machinists. So, it increases the cost.

Milling-turning centers or Mill-Turn machines are also helpful in producing complex parts. It includes a combination of CNC milling and CNC turning machines.

Here, the workpiece can rotate at high speed on a rotation axis. After turning operations, the machine sets at a precise angle for milling operations.

Such machines and their cutting tools help improve the productivity of CNC turning. These multi-functional CNC machines are ideal for parts that need many machining operations. One complete cycle of machining can allow faster part production with improved accuracy. Moreover, there is no need for extra setups.

It helps produce more complex parts at a much lower cost than other 5-axis CNC machining options.

What Factors Should You Consider During Complex CNC Machining?

1) The Dimensions and Size of the Part.

Size does not decide the part’s complexity but can be a factor. Remember that more significant planar parts are less challenging than smaller, complex parts.

Thus, dimensional stability plays a crucial role when making parts with intricate shapes.

2) The Cutting Tool.

Consider the size of individual parts, which influences the size of the cutting tool used. A larger, high-speed cutting tool can cut material fast, reducing the machining time.

You can choose from bigger and shorter cutting tools. Of course, their performance depends on the tool head and spindle speed.

3) The Processing Time.

The number of operations, interventions, and tests will also impact the part complexity. The processes may be complex and time-consuming, depending on the geometry and finishes.

For example, a complex part may need several reorientations and manual interventions. So, five axes and mill-turn machines may be the most suitable machine.

4) The Tolerance.

The part tolerances can decide the choice of CNC machine you should use. Besides, it can also affect the cost and lead time. The achievable tolerance is also affected by the cutting material, machining speed, and tooling.

The higher the tolerance, the more your part will cost. Remember, tighter tolerances allow for more precision when making parts with complex shapes.

It may also involve other processes, operations, tools, and machines, thus increasing costs.

What Type of Finishes Can CNC Machines Produce on Complex Parts?

Now, let’s talk about different finishes you can achieve on complex parts. You can check out our surface finishing service to understand all finishing methods.

A) Bead Blasting

Bead blasting is nothing but a manual process. It needs a skilled machinist to perform the finishing operation.

This process helps achieve a smooth satin or matte surface finish. Machinists often use it to remove tooling imprints, spots, and imperfections.

bead blasted

It is crucial to consider the thin layer of material removal. More so if your part has features with tight tolerances.

B) Mirror Polishing

As the name suggests, mirror polishing gives a mirror-like finish. This mechanical process uses finer abrasives to remove imperfections.

Complex parts need this finishing. That’s because it makes the part smooth and reflective, free of scratches.

al6061 cnc milling polished

C) Electropolishing

Electropolishing is another method that provides corrosion resistance. It acts as a corrosive cleaning process.

We need to pass a current through the workpiece immersed in electrolytes in this method. Thus, it offers a smooth surface on intricate parts.

copper c1100 part 3 axis cnc milling polishing 24k goldplating (2)

D) Anodising

Anodising is nothing but an electrochemical process used for giving a coating finish. The anodic coating, i.e., a regular oxide layer, protects the workpiece from corrosion.

al7075 beadblast hard anodizing

Besides, it allows you to include different colors. The layer formed in this process is non-conductive. Most factories prefer to use Hard anodizing and Sulphuric anodizing.

Should You Carry Out CMM Inspection for Complex Parts?

CMM means a coordinate measuring machine. It is a device that we use to measure the physical geometric properties of an object.


A machine operator can use this machine to examine the part’s dimensions. Then, the operator can determine whether the part meets tolerance conditions.

Of course, CMM inspection is crucial when making complex parts. If you need high-precision parts with the best quality and accuracy, go for a CMM inspection. This process also offers precise results since there is no room for human error when processing parts.

This inspection also involves checking the surface finishing of the complex parts.

It helps you confirm that your parts are correct according to their design and drawings.

How To Use a CNC Machine to Make Complex Parts?

Step 1: Design Your Part

The first step involves designing your part. You can follow the standard CNC machining design guidelines when creating a drawing.

Step 2: Export CAD Files

You can export CAD (computer-aided design) files in a proper format. The most common ones include IGS, PARASOLID, and STEP.

You can use STL files if you work on a 3D printing project. Make sure you avoid using OBJ files. That’s because they cannot provide accurate geometric data.

Our post, ‘CAD File Formats for CNC Machining,’ outlines all the above formats.

Step 3: Send the Drawing in a PDF Format

This step may not be mandatory. But we recommend sharing engineering drawings of each part in a PDF format.

A PDF drawing is helpful when your part has tolerances, acute dimensions, or thread holes. You can highlight specific areas in this drawing, such as a threaded hole.

pdf format

Step 4: Get a Free Quotation for Your Part

Your task ends once your design files are ready. After that, you can request a free quotation to manufacture your complex parts.

You can send your drawings to our customer executives. Our design engineers and production staff will review your project.

We work on a range of CNC machining services. So, our team will help you streamline the manufacturing process of your complex parts.

Would you like a significant lead time and reasonable pricing for your complex parts? Request your free quotation now!


As you can see, CNC machining is the ultimate solution for creating complex parts. You have to use a suitable machine and drawing to achieve better results.

No matter how complex the part is, you can still achieve better finishing. You have to pick the right computer numerical control (CNC) machine.

Our skilled engineers have the required expertise in this field. For any query related to CNC machining services, get in touch!

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Hey there, I’m Sam!

From AT-Machining, I’m a CNC Machining Expert in this field for more than 20 years.  We offer cost-effective machining services from China. Ask for a quote for your ongoing or upcoming projects now!

Best Regards, Sam, Co-Founder

AT Machining

On-demand CNC Machining With Custom Finishes. You Design It, We'll Make It.