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What Is CNC Turning?
CNC turning is a highly efficient manufacturing process that operates on the principle of the CNC lathe machine. This effective subtractive machining technique uses specialized cutting tools to remove material from a rotating workpiece held in a chuck to create the desired shape.
The CNC turning center maintains a fixed position while the workpiece material spins at high speed. A turret mounted with a cutting tool moves to the workpiece material at a computer-programmed speed to remove excess material and create the preferred shape.
However, a computer program commands the turning of the machining center or the lathe allowing it to form the desired shape. The turret can hold various special rotating tools. However, the more tools it holds, the higher the options for complexities on the machined part.
There are various CNC machining centers. Some have one spindle compared to some with two spindles –a main and a sub-spindle. The main spindle machines a part partially and passes it to the sub-spindle to add other features.
There are four main types of CNC turning centers. Each has varying power and speed capability, tooling and spindle option, and outer diameter limitations. These are:
- Vertical turning centers
- Horizontal turning centers
- Vertical lathes
- Horizontal lathes
How Does CNC Turning Work?
Although the CNC turning operation works on the CNC lathe machine principle, it can be pretty complex. However, here is a simplified step-by-step breakdown of the process from the design phase to manufacturing. These steps include:
Step 1 – Changing the CAD Design File to CNC Program
The first step to a CNC turning work involves preparing a CAD file for translation into machine language. However, this preparation does not include advanced programming. It only requires some completed engineering drawing of your design. As such, using software like SolidWorks or AutoCAD helps to capture the 2D drawings of your design electronically.
Moreover, you can convert an electronic design in the CAD file format to a CAM program. Also, you can export the drawing in the CAM format using the exact software tools mentioned earlier. The manufacturing engineer can then test the manufacturability of the component using the software.
Step 2 – Prepare the CNC Turning Machine
Setting up the CNC turning center comes after the CAD design file conversion. There is a need for a machinist or operating personnel even though the machining process is automated. However, to prepare the CNC turning lathe effectively, here are some steps to follow:
- Ensure you put off the power, as the CNC machining can be dangerous. Hence, you must be very careful and check the power switches to ensure the power is off.
- Mount the part onto the chuck. The chuck holds the machined part in place during the turning operation. So, not loading the workpiece properly can result in machining complications which could be dangerous.
- Load the turret properly. The turning operation comprises several tools. As a result, you have to choose the right tool for desired finish. The turret holds as many tools as possible, allowing seamless turning operation.
- Maintain proper calibration. You have to place the workpiece and the tool in the correct angles/ positions to ensure that all design requirements are met.
- Uploading the CNC program is the last step before beginning the turning operation. You have to upload the CNC code into the turning machine.
At this stage, there are two variables you have to keep in mind. The turning speed is the first variable. It determines the speed at which the workpiece spins. On the other hand, you need to consider the feed rate, the speed at which the cutting tool moves along a revolving workpiece or bar material.
An expert machinist must be able to determine these values because wrong estimations often lead to bad results—additionally, inappropriate estimates in certain materials result in uneven finishes or fatal damage to the workpiece.
Moreover, it would help to sketch out the shape with a high feed rate and low turning speed. Similarly, you can use a high turning speed and a lower feed rate to achieve smooth finishes and create parts with precise tolerance needs.
Step 3 – Manufacture the CNC Turned Parts
The production of the desired part is the final step of the CNC turning operation. However, there are various turning operations depending on the desired results. In addition, the machined part’s complexity often determines the number of cycles required. Calculating the time for these cycles helps to determine the overall time spent on the component, which is vital for CNC machining cost calculation.
Generally, the turning cycle often includes:
- Loading Time – A cycle may need other alternatives to load the workpiece onto the machinery even though it is part of the machine setup.
- Cutting Time – It covers the time used to cut the workpiece. Factors such as cutting depth and feed rate determine the cutting time.
- Idle Time – Any machining operation that has nothing to do with cutting is an idle operation. For instance, time spent changing the tool’s movement, setting the turning center, etc., is idle time.
More importantly, note that the raw material used in the turning operation often affects the manufacturing process result. A component formed from metal will vary in surface roughness and functionality from that obtained from plastic.
What Are the Advantages of CNC Turning?
The CNC turning process offers a wide range of benefits for your manufacturers and business owners. These high-quality CNC turning machines help improve productivity and reduce production costs. In addition, this cutting process fulfills the precise tolerance requirements of most applications. Here are some of these benefits in detail:
Flexibility
The CNC turning machine possesses turning centers of various sizes, which allows the flexibility of your application. These CNC machines use computer numerical control, which helps its accessible accommodation of adjustments in task execution.
The machine operator can easily finish your components by applying the required programming adjustments to your CAM program or creating something completely different. As a result, if you need many unique parts, you can depend on precision CNC turning services.
Accuracy
CNC turning centers execute precise measurements, eliminating human errors using CAM or CAD files. Trained machinists can achieve extremely high accuracy with the help of next-level machinery for prototyping or the execution of the whole production cycle.
Since the turning center has been preprogrammed, the cutting tool delivers an accurate cut each time. Consequently, the production run’s final product is the same as the first piece.
Versatility
Versatility is another advantage CNC machining businesses get from using the CNC horizontal turning center. These CNC lathe machines can create parts from plastic, glass, metals, and composites.
As a result, it is the go-to solution for various manufacturing needs. Additionally, you can integrate CNC machines with several tooling options, enabling them to execute multiple machining operations.
Faster Results
CNC turning machines are essential for active manufacturing businesses that aim to gain ground in a highly competitive market. When you use CNC turning centers to execute program-specified tasks, there are lower chances of errors. Consequently, these CNC turning services help to manufacture parts faster without compromising the final product’s quality.
The CNC turning machines help businesses to achieve business objectives and mass production irrespective of the requirements. More importantly, you can get the desired components faster and in larger volumes while satisfying your customers’ needs.
Excellent Tolerance
Manufacturers and engineering experts often turn to CNC turning to produce machined parts with incredibly high tolerance. CNC turning offers an excellent surface finish and high tolerances than most techniques.
As a result, manufacturers commonly use this process to add precision rotational features to components whose basic structure has been formed using a different procedure.
Cost Effective
Cost-effectiveness is one benefit that attracts most machining businesses to this process. CNC turning operation helps machining businesses save a great deal of money while offering high-quality products. This is because the process improves scalability, the efficiency of production, and assembly without wasting material.
In addition, this process saves costs as it does not require purchasing new tools to create parts. Similarly, it prevents all expenses due to accidents or work hazards.
Safety
CNC machine shops purposely comply with strict safety rules and regulations to ensure complete safety. The CNC turning operation requires less labor since the turning machine is computer-controlled (automated).
As a result, the machinist is only there to supervise the operation of the machine. Also, the lathe body is semi-closed or fully covered with protective devices. This helps to prevent particles from flying from the processed workpiece, thereby safeguarding the crew from harm.
No High Skill Requirements
CNC turning operation does not require a highly skilled operator to manage the CNC machine. A machinist can complete a course and become certified to operate a CNC turning machine. Consequently, this helps to reduce further costs of production.
Which Materials can CNC turn?
CNC machining processes are compatible with a wide range of materials. However, many of these materials are best machined with a CNC lathe or turning center. Nevertheless, it would help to note that metals are the primary materials used for turning.
These common CNC machining materials include:
- Cast iron
- Alloy steel
- Stainless steel
- Carbon steel
- Zinc
- Aluminum
- Magnesium
- Copper
Other compatible materials include:
Nevertheless, it would help to note that these materials require varying turning centers or lathes due to specific requirements such as feed rate and turning speed.
Is Your Project a Good Fit for CNC Turning?
There are several variables to consider when finding the proper manufacturing process for your project. These factors help to determine if the procedure is suitable for your project. This section explores certain aspects that’ll help determine if CNC turning is the most cost-effective process for your project.
Here are some factors to look at:
- What is the volume of parts required long-term or short-term? CNC turning centers are typically perfect for prototyping to short-run volumes.
- What is the highest outer diameter (OD) of the part? For instance, the CNC turning center at AT Machining has a maximum outer diameter of for collected parts is 2.5 inches.
- Parts exceeding 2.5″ outer diameter are chucked individually. Consequentially, it contributes to the price of turned parts depending on the volume.
- Parts below 1.25″ outer diameter and medium to high volume may be ideal for the Swiss Screw Machines.
- Factors like lead time and projected volume are primary to making the best choice between machining a part using a 32mm Swiss Screw Machine or a CNC turning center. Similarly, you may consider using taper turning when machining cylindrical parts.
Conclusion
CNC turning is a reliable and versatile process that helps several businesses to save money without compromising the quality of machined parts. It would help to note that precision-turned parts are typically superior in quality compared to those machined with alternative techniques. As a result, the CNC turning process gives your business the competitive edge to stay ahead in the marketplace.
AT-Machining is the ideal manufacturing partner whenever you need CNC machining services. We offer reliable machining solutions and advice to make the best decision for your manufacturing project. Reach out to us today for help with your project requirements.
