10 Types of Turning Operations You Should Know

10 Types of Turning Operations -Yonglihao Machinery

Today, turning is a very common method of metal machining. Turning is on the lathe, the use of workpiece rotation and tool linear or curved motion to change the shape and size of the blank, it is a general manufacturing cylindrical parts processing technology.

In production, a CNC lathe can do many turning operations. So, you must learn different turning operations and their features for making parts. The choice of different turning operations can not only enhance the efficiency of parts processing but also improve the quality of parts processing. Next, this article will introduce 10 turning methods. They will help you choose the right one for your project. Now let’s get started!

Table of Contents

Turning

Turning can be categorized into two types: rough turning and finish turning. Rough turning operations are designed to machine a workpiece to within a predetermined thickness by removing the maximum amount of material in the shortest possible time without regard to accuracy or surface finish. Precision turning requires the machining of workpieces with a smooth surface finish and dimensions that require high precision.

Different parts of a turned part may have different outside dimensions. The transition between two surfaces of different diameters may have a variety of topological features, i.e., steps, tapers, chamfers, and contours. To create these features, it may be necessary to perform multiple cuts with small radial depths of cut.

1. Step turning: A tool is utilized to create two surfaces with an abrupt change in diameter between them. A shape resembling a step is created at the end.

2. Taper Turning: Taper turning creates a ramp transition between two surfaces of different diameters due to the tilting motion between the workpiece and the cutting tool.

3. Chamfer Turning: Chamfer turning creates an angular transition between two surfaces with different turning diameters that originally had square edges.

4. Contour Turning: To create the desired contour on the workpiece, it is necessary to use the contouring tool several times. However, molding tools can produce the same contour shape in a single pass.

Turning of metals with CNC lathes-Yonglihao Machinery

Facing

Face machining is the operation of machining the end of a workpiece perpendicular to the axis of rotation, which is done to obtain a smooth surface. This type of machining is essential to achieve accurate end faces and to improve the aesthetics of the workpiece. During end-face machining, the tool is moved radially along the workpiece by removing a thin layer of material and then obtaining a suitable part length and a smooth part surface.

Face machining is used for two main purposes, one is to prepare the workpiece for subsequent turning operations and the other is to obtain a smooth, accurate surface to ensure assembly of the workpiece.

Grooving

Grooving is a turning operation that cuts a groove in a workpiece. The size of the groove cut is related to the width of the cutting tool. Machining wider grooves requires the tool to make multiple cuts.

There are two types of grooving operations, external grooving and face grooving. In external grooving, the tool moves radially to the side of the workpiece and removes material in the direction of the cut. In face grooving, the tool machine grooves the surface of the workpiece.

A grooving tool, also known as a grooving insert, is a specialized cutting tool designed to cut a specific groove profile. Its performance directly affects the quality of the grooving process.

Turning operations on metal shafts in the lathe-Yonglihao Machinery

Parting

Parting, also known as cutting, separates the part from excess material when the part machining cycle is complete. It requires the use of a cutting tool to first create a narrow groove before finally separating the part. It requires precise cutting by the operator, which involves proper alignment and excellent tool control to prevent damage to the part. Part collectors are typically used to collect removed parts.

Drilling

Drilling refers to the use of a drilling tool to remove excess material from the inside of a workpiece and then form a hole of the desired size. Drilling results in a hole with a diameter equal to the size of the drill bit used. The drill bit is usually located in the tailstock or lathe tool holder. However, with prolonged use, the drill may wear out. Then, it may produce a hole with a smaller diameter than the drill size.

Therefore, it is necessary to pay constant attention to the time and number of times the drill tool is used, and when it appears that the diameter of the hole in the processed workpiece becomes smaller, it is necessary to replace the drill tool with a new one in time.

Turning operations on metal shafts in the lathe-Yonglihao Machinery

Boring

Boring, also known as internal round cutting, is the enlargement of a forged, cast, or drilled hole. In boring, the tool enters the workpiece axially, then removes material along the inner surface, and finally forms a different shape or enlarges the existing hole.

Boring can be categorized as rough, semi-fine, and fine boring. Finish-bored holes have a dimensional accuracy of IT8 to IT7 and a surface roughness Ra value of 1.6 to 0.8 μm.

Boring can improve the hole’s accuracy and surface smoothness. It can also straighten the original hole’s axis. Since it cannot create holes, it can only be performed after drilling is completed and is a finishing process for completed holes.

Reaming

Reaming is a method of removing trace metal layers from the walls of workpiece holes with a reamer, which improves the dimensional accuracy of the workpiece and the quality of the hole surface. Reaming is an operation to enlarge the size of the workpiece hole. It is a method of finish machining, that is widely used in the production process, and it is a relatively economical and practical processing method for some smaller holes.

In the reaming operation, the reamer enters the workpiece axially through the end and enlarges the existing hole to the diameter of the tool. Reaming removes a minimum amount of material, is usually performed after drilling, and results in a workpiece of very accurate dimensions and a high finish on the surface of the hole. The reamer is fixed to the tailstock spindle while the workpiece rotates at a very slow speed.

Turning operation cutting tools show-Yonglihao Machinery

Tapping

Lathe tapping is the use of tools to machine the internal hole of a workpiece into the desired internal thread shape. Tapping operations on the lathe generally have the following steps:

1)Selection of tapping tools: tapping operation on the lathe requires the selection of suitable tapping tools. Commonly used tapping tools are taps, tapping knives, and tapping lathes. Different tools are suitable for tapping different materials and specifications.

2) Setting parameters: Before starting the tapping operation on the lathe, some basic parameters need to be set. The first is to select the appropriate feed rate and spindle speed. The feed rate should be determined according to the material and the specification of the tapping tool. The spindle speed should be set according to the diameter of the tapped hole and the hardness of the material.

3) Perform tapping: first of all, carry out trial tapping on the lathe to determine whether the spindle speed and feed speed are appropriate. In the tapping process, regularly invert the tap to discharge chips to prevent chip blockage. When carrying out formal tapping, you need to pay attention to the direction of the feed wheel to ensure smooth and not jittery. In addition, choose the appropriate coolant according to the hardness of the material and the specifications of the tool. For different materials, use proper lubrication and coolant to minimize friction and heat.

So, picking the right tool, setting the right parameters, and mastering the correct techniques can improve tapping efficiency and quality.

Threading

Threading is a turning operation in which a tool is moved along the side of a workpiece to cut threads on the outer surface. Threads are uniform spiral grooves with a specified length and pitch. To obtain deeper threads, the tool needs to make several passes along the side of the workpiece to obtain the desired thread size.

Threads can be turned on a lathe with either a form-turning tool or a thread-combing tool. Using a forming cutter to turn threads is common for making a few threaded workpieces. The cutter is simple. Using a thread comb cutter to turn threads is fast, but the tool is complex. It is only suitable for making short lengths of threads with fine teeth in medium and large batches.

High Precision Turning Operation-Yonglihao Machinery

Knurling

The purpose of knurling is to create a serrated or diamond-shaped pattern on the surface of a workpiece or part. Knurling helps to facilitate the gripping of the machined part and increases clamping friction and the visual appearance of the machined part.

The most common knurling patterns are straight and reticulated. Knurling cutters consist of a roller and a cutter body. Since the knurling process involves the roller rolling the metal layer of the machined surface, causing it to deform plastically to form the pattern, the radial pressure generated during knurling is high.

Conclusion

Turning is vital in CNC machining. Ten methods of machining parts are provided above. It is widely used in many fields of mechanical engineering. If you would like more professional help, please contact Yonglihao Machinery, we have extensive experience and expertise in the CNC machining industry. We can provide the best CNC turning solutions for all your prototyping and production needs. Satisfy your various parts needs.

FAQ

Rough turning is the roughing process in machining. It mainly cuts the excess material on the surface of the workpiece. The workpiece is usually not highly accurate. Finishing turning is the finishing process in the machining process, which needs to ensure the dimensional tolerance, shape, and position tolerance, surface roughness, and other corresponding requirements of the product. Roughing accuracy is up to IT12 ~ ITll with a Ra of 50 ~ 12.5 μm. Finishing accuracy is up to IT8 ~ IT6 with Ra of 1.6 ~ 0.8 μm.

Choosing the right grooving process can optimize grooving results. It can also improve efficiency and quality. For the general shape of the groove, direct cutting can be used; in the face of deeper grooves, it is necessary to use the pecking cycle instruction for chip processing; wider grooves are selected to groove + transverse turning method for processing; circular grooves are processed as far as possible by using the rounded head of the turning tool and the tip of the tool arc semi-fine compensation instruction for processing.

Cutting can lead to cutting deformation being relatively large, cutting force being large, cutting heat concentration, cutting tool rigidity being relatively poor, chip removal being more difficult, and other shortcomings. Therefore, the quality of cutting directly affects the surface and shape of the part. The cutting process is critical to size and shape.

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