“CNC Turning revolutionizes manufacturing by producing precise, symmetrical parts. It supports complex needs in medical, military, electronics, automotive, and aerospace industries.”
The cnc lathe machining helps produce complex parts for medical, military, electronics, automobile, and aircraft applications. This article briefly discusses the ten most common operations that can be done on a lathe. A lathe can perform numerous operations to produce parts with desired properties. “turning” is a general term for machining on a lathe. Still, it is only one of the many possible operations. Multiple operations can be carried out on a lathe depending on the tool ends and the relative motion between the tool and the workpiece.
The common types of cnc lathe turning are facing operation, grooving operation, parting operation, threading operation, drilling operation, tedious operation, knurling operation, and tapping operation. This article entails information about commonly employed types of turning operations.
What Is Turning: A Brief Overview
CNC turning
Machining is the primary process on a lathe; the main operation carried out is turning. Turning is a metal cutting process in which a cutting tool is fed against the rotating workpiece to remove material from its outer periphery. The main objective of turning machining is to reduce the diameter of the workpiece to the required size. There are two main types of turning: rough turning and finish turning.
Rough turning deals with removing a large amount of metal faster to achieve the required thickness of a particular component with less concern for accuracy and surface finish.
Finish turning, on the other hand, helps achieve a better surface finish and dimensions. Steps, tapers, chamfers, and contours may be used when changing from one surface to another of different diameters. Several passes at a small radial depth of cut are expected to be made to obtain these features.
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How Does the Turning Process Work?
Turning is a machining operation in which a cutting tool is fed parallel to the axis of the rotating workpiece to impart the desired shape to it. The steps for turning machining include
- Preparation: Put the workpiece on the lathe and take the right roughing or finishing tool, depending on the feed type required.
- Setting Parameters: Select the correct speed and feed rate suitable for the material and the width of the cut to be made.
- Initial Cut: Switch on the lathe and then switch the light cut to the required length on the right side of the workpiece.
- Pause and Measure: Switch off the lathe with the cross-feed screw handle, not in motion. Determine how much material has to be removed from the workpiece by measuring the workpiece.
- Material Calculation: Find out how much of the material has to be removed to obtain the desired part size.
- Final Adjustments: Finally, inspect the turned workpiece for any defects and correct them to achieve the best results in accuracy and quality.
Essential Tools and Equipment for Turning
Turning is a fundamental metal-cutting process that uses various tools and machines to improve precision and efficiency. Here are the critical components involved: These are the significant parts that are involved:
Lathe Machine
The turning tool, the lathe machine, is the leading equipment used in turning processes. Some operations using lathes include turret lathes, special purpose lathes, and computer numerical control lathes.
Single Point Cutting Tool
Turning involves single-point cutting tools made of high-speed steel or carbide. The tool’s design influences the turning process, such as the cutting edge’s angle and the tool’s hardness.
Chuck
The chuck is used to grip the workpiece while the latter rotates to ensure it is well-positioned and aligned.
Tailstock
The tailstock holds the workpiece when turning between centers to guarantee it is in the correct position.
Feed Mechanism
The feed mechanism is usually determined by a lead screw, which determines the speed at which the cutting tool feeds on the workpiece, the quality of the cut, and the rate at which it is done.
Key Parameters in Turning
The parameters mentioned below must be regulated to optimize the turning process. Knowledge of these factors can improve the quality and productivity of the operation:
Cutting Speed
Cutting speed is measured in meters per minute or feet per minute and is the speed at which the cutting tool or the workpiece travels. It affects the quality of the cut that is made, the life span of the tools used, and the productivity of the work done. Key considerations include:
- The type of material used in the making of the tool and the hardness of the material.
- Cutting tool material
- Desired surface finish
Depth of Cut
The depth of cut is the amount by which the tool penetrates the workpiece. It influences the cutting tool’s production rate, surface finish, and wear. Important considerations are:
- Reducing the chances of getting cuts that are either too shallow or too deep
- The type of material used and the hardness used to make the item.
- Tool capability
Feed Rate
Feed rate is the tool’s advance along the workpiece per revolution. It influences the quality of the finish of the workpiece, the tool wear, and the production rate. Key factors include:
- A faster feed rate for higher production rates
- Alterations of the material and the tool to obtain the optimal result
Other Important Parameters
- Tool Geometry: Rake and relief angles are used on the cutting tool to decide the cutting action and surface finish.
- Workpiece Material: Due to the dissimilar nature of the material, it becomes obligatory to alter the speed, feed rate, and tool.
Types of CNC Turning Operations
Turning operations are significant in CNC machining to produce complex parts in the medical, military, electronics, automotive, and aerospace industries. Here are ten different types of turning operations explained step by step, starting with straight turning:
- CNC Tapping
CNC tapping
Tapping derives its name from the tool used in the operation. A hole has been drilled in the workpiece through which the tapping tool is inserted axially. With the help of a tailstock spindle, the tapping machine holds the workpiece on the faceplate and rotates it on a fixed faceplate. Tapping forms threads in holes, which are helpful in assembly applications in aerospace, home appliances, and automobiles. Through holes are properly tapped to provide the proper standards for fixing components to be easily assembled and disassembled.
Drilling the hole is essential to tapping and must be done accurately. Inadequate drilling may result in the reduction of the material strength around the hole and the creation of stripped threads or compromised components.
- CNC Threading
CNC threading
Threading is the process of producing a thread on the surface of the workpiece by using a cutting tool. It cuts spiral grooves called threads on the workpiece, which have standard lengths, pitch, and depth. Deeper threads need the tool passed through the rotating workpiece more than once. The threading tool is shaped like the thread to fit into the slot. It is essential to set up the machine correctly to get consistent deeper threads, as the machine has to start grooving from the correct location. Thread cutting creates threads on nuts, and selecting the tapping tool and workpiece material is critical.
- CNC Boring
CNC boring
Boring is similar to turning in that it employs a single-point cutting tool to increase the size and finish of an existing hole in a workpiece. The tool, generally a thin rod with a cutting edge, enhances the hole’s surface and precision and smooths the cylindrical surface. Boring refines the hole by cutting out unwanted material from the hole to allow for fitting other parts, such as shafts and bearings. Boring can be done radially or axially because the boring process commences along the centerline.
- CNC Knurling
CNC knurling
They are knurling forms of diamond shapes or serrations on the surface of a workpiece to make it aesthetically appealing and to get a better grip on the workpiece to avoid slipping during handling. The knurling tool has cylindrical wheels with teeth rolled against the workpiece to produce the required patterns. Knurling is utilized in tools where a firm grip is needed, and the tool is easy to handle, such as handles and knobs. However, the process can reduce the outer surface strength of the workpiece because of the pressing action of the knurling tool.
- CNC Reaming
CNC reaming
Reaming is the process that is done after boring to make a hole larger to a specific size and shape. The fluted reamer, a cutting tool, is inserted in the axial direction. Only a tiny amount of material is cut gradually to make the hole’s diameter equal to the reamer’s. Reaming is useful when achieving high surface finish and close tolerances, such as in manufacturing bearings and valves are needed.
- CNC Drilling
Precision CNC drilling
Drilling is making a hole in the workpiece material by cutting the excess material with the help of a drilling machine. The diameter of the drilling machine and the diameter of the hole are equal. Correct positioning of the drilling machine, mainly using a lathe machine or a tailstock drill holder, is vital to get the most appropriate holes. Drilling is a basic, effective, and universal method.
- CNC Facing
CNC facing
Facing decreases the dimensions of a workpiece by cutting a material from its surface. In the machining process, if the workpiece length is longer than necessary, facing reduces the required length. The facing machine smoothes the ends of cylindrical items, while the cutting tool is parallel to the workpiece’s circumference. Facing is necessary for components that must be positioned and assembled, but it eliminates a lot of material.
- CNC Grooving
CNC grooving
Grooving, also called necking or processing, results in the formation of narrow slots in the workpiece. The width of the cutting tool defines the size of the cut, and if the cut is more comprehensive, it will need to be done in several passes. Grooving operations include:
- Face Grooving: Forms a cut on the interior surface of one of the faces of the workpiece.
- External Grooving: The cutting tool oscillates along the radial direction of the workpiece to make a skinny slot on the outer surface.
These operations are basic in creating parts with required characteristics and dimensions, which are critical in determining the quality of the final product.
- CNC Parting
CNC parting
Machining is a process of removing material from a workpiece to obtain a desired shape. Parting is an essential last operation in manufacturing used to separate a finished component from the bar stock. A tool with a specific geometry enters the rotating workpiece and gradually cuts it until it gets to the center, and the part falls off. A part catcher is commonly used to avoid the scattering of the parts. This step comes after the workpiece has been machined to the required size and shape of the workpiece.
This operation benefits industries where many similar items are manufactured from a single material bar. It enhances productivity since the whole part-making process is done in a single operation at the CNC turning center. However, it is crucial to accurately program the parting line to prevent uneven surfaces on the parts or producing too much scrap.
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Comparing Rough Turning Vs. Finish Turning
Rough turning is the first process of turning operations where a large quantity of material is removed from the workpiece. This process rapidly brings the workpiece near to its final form, which is beneficial for further operations. The primary benefit of rough turning is that it is a fast process of removing large amounts of material, which increases efficiency. However, the components produced during rough turning may not be as accurate as the fine turning ones.
Rough vs finish turning
On the other hand, finish turning concentrates on rubbing the workpiece slightly to get the desired dimensions and surface finish. This is the last process of machining that is essential to ensure that the component has a very smooth surface, close flatness, the right thickness, and the correct dimensions. Some conditions that may affect the quality of the surface finish during finish turning include the state of the cutting tool, the built-up edge, and the kind of chips produced. This process helps achieve the necessary machining standards on the workpiece before it is finished.
Choosing the Right Turning Operations: Factors to Consider
In the application of CNC turning in projects, selecting suitable turning operations is very vital to the outcome of the project. Here are some factors that will help in the decision-making process:
Material Characteristics
The machinability of materials also differs from one material to the other. Some relatively soft metals to pressure include aluminum; these materials give a smooth cut, but the mechanical strength is most probably compromised when deep cuts are made on the material. On the other hand, materials like steel can be machined to deeper depths without affecting much of the material’s strength. This knowledge assists in attaining the best results and durability of the material where specific turning operations are to be performed.
Accuracy Requirements
Each turning operation that the CNC performs has its tolerance levels that can be attained. Amongst the operations, turning and facing are most appropriate for producing accurate cylindrical shapes and flat surfaces. On the other hand, processes such as drilling or knurling may introduce minor errors due to factors such as the bending of the tool or oscillation. Thus, choosing the operations that will provide the required dimensional accuracy while not altering the design specifications is vital.
Surface Finish
As mentioned before, turning operations per se have different effects on the quality of the surface finish. As a rule, turning and facing are superior to drilling or knurling. In addition, other operations like reaming and polishing may be applied to enhance the surface finish of the hole. Understanding how surface finish influences functionality and appearance allows one to select the right turning operations for the application.
Shape and Feature Requirements
Turning processes are categorized based on the kind of form or characteristic produced. Forming bends the components into cylindrical ones, facing flat surfaces, and threading forms external or internal threads. The alignment of the operation with the target outcome is the key to achieving production efficiency and the part’s correct specifications. Moreover, several operations can be integrated into a single cell, which enhances the use of CNC turning; it is also possible to manufacture complex parts without much translation of the workpiece.
Materials Suitable for Turning Processes
Turning processes are suitable for all materials, mainly metals, but can also be applied to some plastics. The available metal choices are steel, brass, aluminum, nickel alloys, and titanium. The plastics appropriate for turning operations include polycarbonate, PEEK, PEI, and PP.
In the case of turning, the material to be used is determined by its ability to be machined to the required surface finish when cutting solid materials such as steel, the right tools are used, such as high-speed steel or carbide tools, which are ideal for high-power applications and cutting forces specific to a particular operation.
Some well-known materials are aluminum and titanium, which are highly suitable for smooth surface finishes and for machining various shapes and sizes. Because of this, they are ideal in several manufacturing processes that demand accuracy and adaptability.
Design Strategies for Optimal Turning Results
Concerning the choice of turning processes, Below are the main strategies that can be used to enhance the productivity of the manufacturing process and ensure the quality of the outcomes:
Maintain Uniform Wall Thickness
The turning process is critical to the uniformity of the thickness of the walls in part designs. It is not only a party establishing the cost of production and the time it takes to achieve it but also a critical component of running the final product.
Simplify Designs
It should be made as easy as possible in design to avoid becoming complex. The complexity of the designs increases the likelihood of encountering some machining difficulties, reducing the production rate and increasing the time taken to produce the products.
Standardize Thread Sizes
In turning operations, it is recommended that standard thread sizes be used; this means that it will take a shorter time to set the machines, and the special tools are relatively expensive. It also enhances the quality and efficiency of products produced in the production line.
Optimize for Single Setup Machining
Those parts produced in one operation should be produced that way because it is most effective on the shop floor. It also raises the speed of production and the quality of the process because there are few tool changes and setup modifications.
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Differences Between Turning Centers and Lathes
Turning centers and lathes are fundamental tools in machining processes, each offering unique advantages. A turner center and lathe are some of the most fundamental tools that are used in the machining processes, and both of them have their advantages:
Turning Centers (Prolean’s Advanced Solution): Prolean’s turning centers have provisions for turret-cutting tools for automatic tool changes, chips, and coolants. These machines are most appropriate in multi-axis operations, making it possible to cut shapes with very high accuracy. They are helpful in applications that require accuracy and flexibility and are widely applied in industries that require automation.
Lathes: Although lathes are used in turning operations, they use stationary cutting tools to cut the rotating material. Lathes are used in production processes that call for accuracy, which means that the operators should be very competent in avoiding oscillations. They are applied in workshops where straightforward cutting processes can be accomplished using basic procedures, and they are less sophisticated than turning centers.
Alternative Machining Technologies to Turning
Beyond turning, several alternative machining methods offer unique capabilities. Apart from turning, other processes in machining have unique characteristics, which include;
Milling: The milling processes used rotary cutting tools to secure non-rotating work pieces into various forms and shapes. In the turning operation, the workpiece rotates, while in the milling operation, the cutting tools rotate and can produce complex shapes and fine surface finish.
Grinding: Grinding uses abrasives to get very smooth surface finishes and high levels of accuracy in dimensions. It is the best in mold making, especially when finishing complex materials and attaining small limits on cylindrical, flat, or conical surfaces.
Turning Solutions with Prolean
Prolean has the best flexible cnc turning service to meet the highest manufacturing requirements. Modern computer numerical control (CNC) machines and a skilled workforce are employed to provide the best finish on intricate parts and surfaces. The quality and efficiency assurance of Prolean ensures that the firm delivers reliable and cheap solutions in prototyping and production to various industries.
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