Introduction:
As we all know, to perform a particular operation in any machine we need to use some attachments such as mandrels and rests. There are different Types of Mandrels and Rests used in the manufacturing industry. The Mandrels and Rests both are generally used in Lathe machines to perform operations on cylindrical jobs. Mandrels are used for hollow cylindrical jobs, whereas rests are used for solid cylindrical jobs.
Why do we need to use Mandrels or Rests?
Suppose you are going for a facing operation on a hollow cylindrical job, you generally hold the job with the help of a chuck, and then performed the operation. So what would be its effect? When you apply the depth of cut to the job, it may be misaligned from the lathe center and you see some error on the workpiece. Mandrels are used for holding and rotating the hollow jobs, as you can fit the mandrel inside the hollow job, and start the machine.
Due to the friction, the mandrel along with the job will start rotating. When you apply the depth of cut to the workpiece, as it compact in setup, it can’t be misaligned and you can get a good surface finish. The mandrel is placed in the center and rotated by the driving plate and lathe dog. Generally, all the Mandrels are made of High Carbon Steel and Mild Steel also.
What are Mandrels?
Mandrels are tools used in the process of turning or shaping materials on a lathe. The mandrel is used to hold the material in place, allowing the operator to work on it with precision. Mandrels come in many shapes and sizes and are made from various materials, such as steel, aluminum, and plastic. They are used in a wide range of industries, including manufacturing, woodworking, and metalworking. In addition to holding the material in place, mandrels can also be used to create internal shapes or contours on the material being worked on. They are an essential tool in the process of creating precise and accurate shapes on a lathe.
Types of Mandrels:
Mandrels are classified into 7-different types which are as follows:
- Plain Mandrel
- Step Mandrel
- Gang Mandrel
- Collar Mandrel
- Screwed Mandrel
- Cone Mandrel
- Expansion Mandrel
Plain Mandrel:
This is a very simple type of mandrel generally available in all the machine shops. Plain Mandrels looks like a solid cylindrical tapered bar whose one side is larger in diameter and the other side is smaller in diameter. At both ends of the mandrel, there is a slot, one is for the lathe dog, and the other one is a protected center hole for the dead center.
Step Mandrel:
This type of mandrel can be used for several jobs of different diameters. Step Mandrels are not just a hollow round bar. Different diameter step collars are fitted with it so that a single mandrel can be used for holding various diameters jobs.
Gang Mandrel:
This is a type of step mandrel. The only difference here is a number of equivalent hollow jobs can be machined at a time. It is used to reduce machining time and is generally used for mass production purposes. In a gang mandrel, a fixed collar is fitted on one side of the solid bar (mandrel) and then Jobs are placed through another side. Then a nut is used to tighten the jobs with the help of a washer.
Collar Mandrel:
Generally, this type of mandrel is used for a job diameter of over 90-100 mm. In this type of mandrel, there are two fixed collars attached at the two ends of the bars. We use this type of mandrel to reduce the weight and cost of the mandrel. If we used a solid bar, the cost and weight of the bar is very high. So instead of that, we can use a Collar mandrel.
Screwed Mandrel:
As the name denotes the peripheral area for this type of mandrel is threaded. A screwed mandrel is a tool used in metalworking and woodworking that consists of a threaded rod with a tapered end. It is designed to hold and support materials, such as wood, metal, or plastic, during the manufacturing process.
The tapered end of the screwed mandrel is inserted into a pre-drilled hole in the material, and then the threaded rod is turned to securely hold the material in place. The mandrel can be attached to a lathe or other machine to allow precision shaping and cutting of the material. Screwed mandrels come in various sizes and shapes to accommodate a range of materials and applications. They are often used in turning and drilling operations to hold materials in place while they are being worked on.
Cone Mandrel:
A cone mandrel is a type of mandrel used in metalworking and other manufacturing processes. It consists of a tapered rod with a conical shape that is used to hold and shape various materials during fabrication. The cone mandrel can be made from different materials, such as steel or aluminum, and can vary in size and shape depending on the specific application. They are often used in metalworking to shape and form tubes, pipes, and other hollow metal objects.
To use a cone mandrel, the tapered end is inserted into the opening of the material being worked on. The mandrel is then clamped in place and the material is shaped by pressing it against the mandrel while rotating it. The cone shape of the mandrel allows for a range of different shapes to be formed, from gentle curves to more dramatic angles. Cone mandrels are commonly used in metalworking industries such as plumbing, automotive manufacturing, and aerospace. They can also be used in jewelry making, woodworking, and other crafts.
Expansion Mandrel:
It is used for jobs of different diameters. The hollow job can be fitted on the sleeve and the job is tightened by the expanding nature of the sleeve with the help of two slots. After fitting the hollow job over the expansion mandrel, we need to push a pin through the center of the mandrel, so that the slots expand and fit with the workpiece.
How to use Mandrels?
Using mandrels on a lathe is a crucial skill for any machinist or woodworker. Following are the steps that are needed to keep in mind while working with mandrels:
- To use a mandrel, you must first select the appropriate size and type for your project.
- Next, attach the mandrel to your lathe according to the manufacturer’s instructions.
- Insert your workpiece onto the mandrel and tighten any screws or clamps to secure it in place.
- Once your workpiece is securely fastened, you can begin to shape, drill, or turn it with your lathe.
Always use caution and follow proper safety procedures when using a lathe and a mandrel. With practice and experience, you can become proficient at using mandrels to create high-quality, precise workpieces.
What is a Rest?
Rests is essentially a movable support that can be adjusted and positioned according to the required operation. The rest helps to stabilize the cutting tool and ensure that it remains in the correct position during use, which is essential for achieving accurate and precise cuts. There are various types of rests available for lathes, including the steady rest, follower rest, and traveling rest, each with its specific functions and applications. The type of rest used will depend on the material being machined, the size of the workpiece, and the type of operation being performed. A properly adjusted and positioned rest can significantly improve the quality and accuracy of the machining process.
Types of Rest:
There are two types of Rests we use in a workshop:
- Steady rest or Fixed Steady
- Follower reset or Travelling Rest
Steady Rest:
It is used when we perform machining or drilling operations by holding the job in the chuck. Steady rest is fitted on one side of the lathe bed at a fixed position, and it is used for the prevention of bending, which is applied by the cutting tool or under its (Workpiece) own weight. A steady jaw consists of three jaws that are 120 degrees apart from each other. Two of these jaws are adjustable and the other one is fixed. We can use more than one rest depending on the length of the workpiece.
Follower Rest:
Follower rest is generally used for the turning operation of a thin round bar. The follower rest is connected to the lathe carriage and that’s why it can be moved accordingly with the carriage. The follower rest is placed on the opposite right side of the tool post. We only need one follower rest to complete any length of the job as it moves accordingly with the tool post and gives continuous support to the job.
Conclusion
In conclusion, these are essential tools in the lathe machining process. A lathe machine is incomplete without these tools. The different types of mandrels and rests, including expansion mandrels, collet mandrels, and steady rests, are designed to accommodate different types of workpieces and ensure optimal precision and accuracy. The choice of mandrel or rest depends on the specific requirements of the project at hand. With the right mandrel or rest, a lathe machine can be used to produce precise and high-quality workpieces with ease.
Short Video on Lathe Machine Parts
Some More Resources for You:
Lathe Machine in Depth Overview
Drilling Machine Overview
Milling Machine in Depth Guide
