Lathe Machine Operations and Lathe Cutting Tools

Lathe machines create sophisticated parts for medical, military, electronics, automotive, and aerospace applications. Read on to find out the top 10 machining operations performed on a lathe.

A lathe is capable of performing numerous machining operations to deliver parts with the desired features. Turning is a popular name for machining on a lathe. Nevertheless, turning is just one kind of lathe operation.

The variation of tool ends and a kinematic relation between the tool and workpiece results in different operations on a lathe. The most common lathe operations are turning, facing, grooving, parting, threading, drilling, boring, knurling, and tapping.

Lathe Machine Operations

A lathe is a machine that rotates the piece on the axis in order to perform various operations like cutting, facing, knurling, deformation, and more.

Metal spinning, thermal spraying, woodturning, and metalworking are the common operations performed with a lathe machine.

The general operations done with the lathe are grooving, turning, cutting, grinding, sanding, etc. In order to operate the lathe first, you must know the feed rates, cutting speed, depth of cut, and how the tool is used.

Each lathe operation has its own factors that must be considered before starting work.

The factors should be used properly so that mishandling and mishaps are avoided in any type of lathe operation. With every cut desired the speed, depth, and feed of the lathe are changed for reasons of precision.

Types of Lathe Operation

The working of the lathe machine changes with every operation and cut desired. There is a lot of operation used for using the lathe machine. Some of the common lathe operations are:

#1. Turning.

Turning is the most common lathe machining operation. During the turning process, a cutting tool removes material from the outer diameter of a rotating workpiece.

The main objective of turning is to reduce the workpiece diameter to the desired dimension. There are two types of turning operations, rough and finish.

Rough turning operation aims to machine a piece to within a predefined thickness, by removing the maximum amount of material in the shortest possible time, disregarding the accuracy and surface finish.

Finish turning produces a smooth surface finish and the workpiece with final accurate dimensions.

Different sections of the turned parts may have different outer dimensions. The transition between the surfaces with two different diameters can have several topological features, namely step, taper, chamfer, and contour. To produce these features, multiple passes at a small radial depth of cut may be necessary.

• Step Turning. Step turning creates two surfaces with an abrupt change in diameters between them. The final feature resembles a step.
• Taper Turning. Taper turning produces a ramp transition between the two surfaces with different diameters due to the angled motion between the workpiece and a cutting tool.
• Chamfer Turning. Similar to the step turning, chamfer turning creates angled transition of an otherwise square edge between two surfaces with different turned diameters.
• Contour Turning. In contour turning operation, the cutting tool axially follows the path with a predefined geometry. Multiple passes of a contouring tool are necessary to create desired contours in the workpiece. However, form tools can produce the same contour shape is a single pass.

#2. Facing.

The facing is a turning operation used to make the end surface of the workpiece flat and smooth. Almost every lathe machine operator performs a facing operation before any other operation.

Here is the step-by-step process to perform the facing operation:

First, clamp your workpiece on the lathe chuck, and move your cutting tool near the end surface of the workpiece. Set the depth of cut as per your requirement. Now start the motor and slowly feed the cutting tool inwards.

#3. Grooving.

Generally, you can perform two types of grooves on a lathe machine: OD grooves and ID grooves. You have to use different grooving tools for each operation.

Unlike turning operations, where you cut workpiece in multiple directions, a grooving tool is normally used to cut in a single direction only. Well, of course, there are some exceptions such as relief grooving which takes place at 45°, where the cutting insert angle and the infeed angle must be identical (usually at 45°).

#4. Parting.

Parting is a machining operation where you cut your workpiece into two pieces with the help of a thin and long parting tool that looks like a blade.

Sometimes you have a long bar, but you only need a small piece of that bar to make a workpiece. In this situation, the parting operation will be the best option to cut out any size of the piece from the raw bar.

#5. Threading.

Threading is a turning operation in which a tool moves along the side of the workpiece, cutting threads in the outer surface. A thread is a uniform helical groove of specified length and pitch. Deeper threads need multiple passes of a tool.

#6. Knurling.

Knurling operation produces serrated patterns on the surface of a part. Knurling increases the gripping friction and the visual outlook of the machined part.

This machining process utilizes a unique tool that consists of a single or multiple cylindrical wheels (knurls) which can rotate inside the tool holders.

The knurls contain teeth that are rolled against the surface of the workpiece to form serrated patterns. The most common knurling pastern is a diamond pattern.

#7. Drilling.

Drilling operation removes the material from the inside of a workpiece. The result of drilling is a hole with a diameter equal to the size of the utilized drill bit. Drill bits are usually positioned either on a tailstock or a lathe tool holder.

#8. Reaming.

Reaming is a sizing operation that enlarges the hole in the workpiece. In reaming operations, reamer enters the workpiece axially through the end and expands an existing hole to the diameter of the tool.

Reaming removes a minimal amount of material and is often performed after drilling to obtain both a more accurate diameter and a smoother internal finish.

#9. Boring.

Boring is a cutting operation where you use a single-point cutting tool or a boring head to produce conical or cylindrical surfaces by enlarging an existing opening in a workpiece.

Boring operation is used to enlarge holes or to cut a tapered hole. The surface formed by this operation is called a bore.

#10. Tapping.

Tapping is the process in which a tapping tool enters the workpiece axially and cuts the threads into an existing hole.

The hole matches a corresponding bit size that can accommodate the desired tapping tool. Tapping is also the operation used to make a thread on nuts.

Lathe Cutting Tools

A lathe is a machine that rotates the workpiece about an axis of rotation to perform various operations such as turning, undercutting, knurling, drilling, facing, boring, and cutting, with lathe cutting tools that are applied to the workpiece to create an object with symmetry about that axis.

For general purpose work, the tool used is a single point tool, but for special operations, multipoint tools may use. Watch the below-mentioned video to get understand lathe machine operation.

In lathe machine work, different operations require different types of lathe cutting tools, according to the process of using the lathe cutting tools. which are as follow,

Types of Lathe Cutting Tools​

There is a wide range of lathe tools that can be classified according to materials, structures and purposes or uses.

• Turning Tool: Turning tools are designed for removing the materials from the stock, a rough turning tool is used to remove the maximum amount of material and the finishing turning tool is serve for good surface quality, just remove a small amount, to make the piece more accurate.
• Boring Bar: A boring bar is required when you want to make an existed hole bigger, a boring bar can easily bore into the hole that is already drilled, and widen its diameter. It can enlarge the hole quickly and process it in the proper size to fit other components correctly.
• Chamfering Tool: Chamfer is a transitional edge between two faces of an object, also defined as a form of the bevel. The chamfering tool is used to create a bevel or furrow on the part. A chamfer can be used to smooth sharp or hazardous edges on a workpiece.
• Knurling Tool: Knurling tools are used to produce knurled lathe parts, through creating or pressing a pattern onto a round section, used as a grip for a handle, also usually created on fasteners like nuts. A knurling tool is designed with a specific pattern.
• Parting Tool: A parting tool refers to a narrow-bladed tool used in turning or planing or for cutting a piece in two, or defined as a tool used for cutting off pieces from the main body of stock being machined, it is manufactured in many forms.
• Thread Cutting Tool: Thread cutting tools are used to cut a thread on the lathe part. In external thread cutting, the piece can be held in a chuck or mounted between two centers, in internal thread cutting, the part is held in a chuck, the tool moves across the part linearly, taking chips off the workpiece with each pass.
• Facing Tool: A facing tool is used for facing operation on the lathe to cut flat surface perpendicular to the piece’s rotational axis, the tool is mounted into a tool holder that rests on the carriage of the lathe, during the process, the facing tool will feed perpendicularly across the rotational axis of the part.
• Grooving Tool: A grooving tool is usually a carbide insert mounted in a special tool holder, it’s designed to an insert with multiple tips, often ground to the dimensions and shape required for a particular job, including cutting a slot and complete other work.
• Forming Tool: Forming tools are made flat or circular in shape when used in the lathe. Simple forming tools have cutting edges ground to the shape of the groove, undercut, or thread to be cut.
• Shoulder Turning Tool: A square shoulder is turned by a knife-edge turning tool or facing tool. A beveled shoulder may be turned by a straight turning tool having a side cutting edge angle and zero nose radius. A filleted shoulder is turned by a straight turning tool with a nose radius corresponding to the fillet radius of the work.
• Counterboring Tool: The counterboring operation can be performed by an ordinary boring tool. The tool cutting edge is so ground that it can leave a shoulder after turning. A counterbore having multiple cutting edges is commonly used.
• Undercutting Tool: Undercutting or grooving tool has a point and form of the cutting edge exactly similar to the form of the required groove. Clearance angle is given at all the sides of the tool. For the recessing groove cutting edge, the longitudinal feed is employed. The front clearance angle depends upon the bore of the work.

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