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large cnc turning

Large CNC Machining: The Essential

Producing large parts with traditional methods is not always feasible, but large CNC machining makes machining these parts possible. Besides, many industries, including mining, agriculture, construction, and oil and gas, require large machining.

Large CNC Machining involves making products of large diameter weighing up to 100 tons. The CNC machines used for this process often have many large-diameter machining equipment and parts, as well as simple and complex shapes. Furthermore, before committing to fabrication, there is always a simulation of the large machining capabilities. This helps improve quality while reducing the cost of production.

So, what exactly is Large CNC Machining? What are the applications of the parts produced through this process? What are the factors to consider machining large parts? Keep reading as we answer these questions and shed more light on Large CNC machining.

What is Large CNC Machining?

what is large cnc machining
Large CNC Machining

This is a CNC machining process used in making large machine parts. It is a subtractive process like conventional CNC machining, but it is not as straightforward. In this process, the computer directs different machine tools to remove parts from a large workpiece during the machining process.

There are four main steps to the Large CNC machining process;

Design Creation Through Computer-Aided Design (CAD) software

This first step involves creating a model design of the Large machine part. This model could be either 2D or 3D. Software is used for this process, with design dependent on product requirements. CAD model design shows operator critical features and other features necessary for effective machinings like tolerance, threads, and construction lines.

Conversion of CAD files into Numerical Codes The CNC equipment can Digitally Read

Since CNC machines do not understand CAD models, it becomes imperative to convert the model to a format they can interpret effectively. This conversion involves the use of CAM software.

This software converts CAD models to CNC-compatible formats and instructs the CNC machine on machining parameters such as cutting sequences. Other instructions include rotational and linear movement, toolpath, machine speed, and the workpiece.

Preparation and Positioning of the Tooling and Workpiece

Having transformed the CAD models into codes, the next step in the process is preparing for machining. Preparation involves selecting the adequate CNC machine for the process, choosing the tooling, and configuring operations. 

The type of CNC machine and process chosen depends on design complexity, budget, and workpiece material. 

Automated Part Generation

This is the final step in CNC machining. It involves beginning the machining process. However, before kick-starting the process, it is important to carry out one final check to ensure the attachment of important cutting tools. 

Application of Large CNC Machined Parts

Many industries use Large CNC machining to produce their parts and large components. However, the most common industries include; Automotive, Aviation, Energy and Power Generation, Mining, and oil and gas. In more detail, let us examine these industries and their capacity and demand for large parts.


Although the automotive industry machines their prototype vehicles using small-scale CNC machining, they favor large CNC machining in real-time production. This is especially true when making vehicle components like engines, shafts, cylinder heads, and gearboxes.


The aerospace sector is another industry that uses large CNC machining for producing parts. There are many reasons this sector employs large CNC machining. First, its high accuracy and precision. Another reason is the ease of producing replacement parts and upgrading machine parts.

Energy and Power Generation

There is a need for large parts of energy generation to be sufficient. Only large CNC machining has the capability of manufacturing these parts. The application of Large CNC machining in the energy and power generation industry includes the production of wind turbine casing and power generation engines.


Equipment used in the mining sector usually has a large size for optimal lifting capacity. They also have high strength, which allows them to withstand mining stress without breaking down. This makes large CNC machining ideal for use in this industry.

Engineers use large CNC machining for making mining industry steel parts such as ranging arms, gear racks, and gearboxes. 

Oil and Gas

The oil and gas industry is another sector that uses large parts and equipment. This equipment, often found in drilling stations, includes steel parts gearboxes, fracking pumps, and connecting rods.

Large Part CNC Machining Considerations

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Large Part CNC Machining

Engineering large parts are not as easy as making smaller parts or materials due to the difference in size. Therefore, before machining large parts, a lot of factors must be taken into consideration. These considerations include;


There are many factors involved in engineering a high-quality design. Understanding these factors is the first step in making a top-quality design. Design factors to consider include;

  • Temperature: Temperature is an important consideration when making large parts. This is because heat is a major byproduct of CNC machining. This heat, which could be due to friction experienced during the process, may change the dimensions of the workpiece. 
  • Working Area: CNC machinery for machining large parts should have a working area, table, or zone. This area allows efficient machining of these parts with minimal distortion.
  • Accuracy and Speed: Professionals in the large-part machining field do not complete the process in a single pass. Instead, they make incremental changes to the design. This type of design, although time-consuming, improves the accuracy of the design. It also eliminates the risks of expensive modifications and delays.


Large CNC machining requires preparing and planning to avoid reverse engineering at the end of manufacturing. You should also note that many components and equipment are needed to machine large parts.

Consequently, it is important to machine large parts in locations with facilities and capabilities to accommodate the weights of this equipment. Here are factors to take into consideration when planning;

  • Collision: Due to the size of the parts, a collision is likely to occur between one part and other materials. This is why optimizing CAD files to eliminate collisions is important. Also, check the ratio of the case interior to that of the design.
  • Weight: The larger the part being machined, the heavier and more difficult it is to work on. This is why it is important to include weight support in planning.
  • Loading Devices: Although these devices do not cut large parts, they are still important. This is because they help load and offload heavy components and those difficult to move.


The tools used in machining standard-diameter parts are quite different from that used in large-diameter machining. Although both tools work the same way, their area of operation sets them apart. Therefore, before undertaking large CNC machining, it is best to get machining tools like cast iron and steel, ideal for large diameters. These tools include; large turnings, large CNC mills, large drilling machinery, large boring machines, etc.

Machining Process

Aside from machining, Knowledge of the right tools and appropriate settings is one of the major considerations in machining. The reason is that a successful large CNC machining process utilizes different equipment and techniques. Common large CNC machining processes include;

multi axis machining
Multi-Axis Machining

This involves machining using a machine that can move along different directions or multiple axes. These axes include; X, Y, and Z axes and the A and B rotational axes. Machining large parts using a multi-axis travel machine results in more efficient machining than using 3 or 4 axes machines. This is mostly because the multi-axis machine processes large part sections from different angles and directions.

contour boring
Contour Boring

Contour boring is a process used to finish uneven surfaces because of the ability of the contouring tool to machine hard-to-reach sections. Using this tool helps smoothen radii and workpiece angles to create quality as well as consistent finishes across the surface of the large part.

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Large Diameter Boring

This process involves rough boring, milling, and finishing. It is a multi-step process that involves boring through metal by carefully centering the cut. The benefit of this boring is that it keeps the material intact by disrupting it minimally.

AT-Machining’s Large Part CNC Machining Capabilities

At AT-machining, large-part CNC machining is one of our numerous capabilities. We have different fabrication services on offer to clients to ensure the success of their large-part machining projects. Our CNC machining capabilities and services include;

Horizontal & CNC Boring

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Horizontal CNC Boring

With our multi-axis horizontal boring mill’s capacity, our Large CNC horizontal machining centers, fully equipped with the right tools, can produce large parts. It also makes complex ones with ± 0.0005 inches precision tolerances. 

CNC Vertical Milling and Planner

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CNC Vertical Milling And Planner

At AT-Machining, we have a vertical machining center with a variety of planner mills as well as three and four-axis CNC machines that can handle any precision machining your project needs. We also do this while maintaining high quality, meeting and surpassing industry standards. 

CNC Turning

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CNC Turning

We have a collection of vertical, horizontal, and CNC lathes in our machining center capable of handling components, castings, and alloys with very large diameters and lengths. The horizontal turning machine makes horizontal machining easier. At AT-Machining, we have a ± 0.001-inch tolerance for CNC turning operations, ensuring the production of parts with high quality.

Other Large CNC Machining Services

Aside from Large CNC machining, AT-Machining offers secondary services such as product assembly, heat treating, plastics manufacturing, hardening, welding, blasting, and repair, as well as other CNC machining services. We are a manufacturing company that takes pride in producing high-quality parts, making us a one-stop shop for all your machining services.


Large-part machining is quite different from smaller-part machining in that the parts are oversized and often require careful handling. Due to their size, they require unique machining considerations, which would help reduce distortions. 

Working with professional machining brands like AT-Machining that have the right equipment helps ensure the machined parts meet tight tolerances. Contact AT-Machining today for your Large CNC machining services.

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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.