In this article, you’ll learn what is Punch tool? and the different types of punches. How they are used in the workshop? explained in detail. Also, download the PDF file of this article at the end.
What is Punch Tool?
After you are done drawing marking lines on a job by scriber or surface gauge, you need different types of punches to make these markings permanent, because there is the possibility of the lines marked with a scriber getting destroyed.
In various industries, they have been using different types of punches in their workshops for a long time. Commonly, a punch is a rigid metal rod with a pointed tip at one end and a dull end at the other.
Typically, punches are available according to their shape of the point. If you are seeking a type of punch for your work, here are some types of punches and their expected use.
Types of Punch Tools
Types of punches are as follows:
- Centre punch
- Prick punch
- Solid punch
- Transfer punch
- Drive punch
- Pin punch
- Roll pin punch
- Hollow punch
- Dot punch
- Bell punch
- Letter stamps
- Tablet punch
- Automatic punch
#1 Centre Punch
These are made of high carbon steel. These are made hard and given temper treatment. Their point is made at a 90° angle and the handling part is knurled. Its length is from 35 mm to 125 mm and its width is from 4 to 12 mm.
Their use is generally made to make a centre at the drilling point so that the drill bit’s point can rest there properly. If this centre is not made by the centre punch, there are chances of slipping of the point and drilling at the wrong point. This type of centre has been illustrated in Figure.
#2 Prick Punch
This is also made of high carbon steel, prick punch is also made hard and tempered. Its point is made at a 30° angle. It is used for marking on jobs of thin metal sheets or to make holes in them. It has been shown in Figure.
#3 Solid Punch
Solid punch is used for boring holes in blacksmithy and sheet metal operations. These are used in different measurements according to the jobs. These are produced of high carbon steel, hardened, and tempered.
While using these in hot jobs it is essential to cool them in cold water. These are used in rough works because holes made with a solid punch are not exactly according to measurements and are not clean.
#4 Transfer Punch
The standard length of such a punch is 4 inches, which is sufficient to move the location of the hole through a pattern or template on the material. A transfer punch is of a specific outer diameter that is non-tapered.
By using the transfer punch you can tight the tolerance of an actual hole and, when struck, it suitably transfers the center of that hole to another surface. This can also be used to fit the drilling and tapping holes in a template to bolt an object to a surface.
#5 Drive Punch
And the sides of this punch will taper the face, in some conditions, you have to use a punch with a straight shank. A straight shank punch is more likely know as a pin or drift punch.
#6 Pin Punch
These types of punches are somewhat different from other punches. It is comparatively larger in length. Instead of being pointed in shape, these are parallel. It is used for tight-fitting pins.
Pin punches can fully turn the rivets and pins out of a hole until they exit the hole, which cannot be done by the other punches. A pin punch has been shown in Figure.
#7 Roll Pin Punch
The roll pin punch is made with a small projection in the center of the pin tip to hold the periphery of the roll pin. The tips of these types of punches are not flat and are used to drive roll pins. It is also known for spring punches.
While using a roll pin punch, ensure that the shank axis of the roll pin punch is consistent with the axis of the roll pin. Do not close the roll pin punch with one side. Whenever you hit a roll pin punch, hit it right on top of its head or it may bend the shank.
#8 Hollow Punch
It is a special type of a hardened steel punch with hollowness as shown in Figure. It is used for cutting holes in metal, cardboard, fabric. These are available in different sets for holes of different sizes.
As they are hollow, the metal which is cut with them falls out through the grooves built on its side. Thus, we can make a number of holes in little time and the holes are quite clear.
#9 Dot Punch
This is by and large similar to the Centre Punch. The main difference is that its point is at a 60° angle. It is used to make permanent the marking done by scribes so that these lines do not obliterate at the time of work. Basically, its length is from 80 mm to 100 mm and its thickness from 3 mm to 5 mm. It has been illustrated in Figure.
#10 Bell Punch
As per its name, it is like a small bell, in shape. Its size is considered according to the circumference of the bell. It is used to find out the center of round jobs and for light marking.
In this circumference, a punch is fixed with the help of a spring, which is like a center punch. For using it its head is hit with a hammer and because of the punch spring, it raises alone.
#11 Letter Punch
The letter stamps are in the form of a reverse image, making the final result quickly readable, although they can be produced as a positive image. It is also known as a number or letter stamp.
These types of punches are used to convert the print of a letter or number into a workpiece. This is necessary for dye or mold making and ensures that the finished product will be readable.
#12 Tablet Punch
This punch is also known as tablet press. Unlike most punches, tablet press punches have a curved end of the desired tablet shape. This tablet press has lower and upper punches to compress the powder between them.
#13 Automatic Punch
This is also a special kind of punch. It is made of high carbon steel which is hardened or tapered. There is no need for a hammer for using this punch.
The main punch is fitted with its body with a spring. Spring remains settled through a lever head. When marking is to be done, its lever head is pressed. Through this pressure, the main punch would be pressed and do the marking.
The blow of the punch can be limited or controlled with the lever head. Its main punch is built at a 60° or 90° angle. This type of punch has been illustrated in Figure.
Precautions of Using Punch
In order to ensure correct and accurate marking with any type of punch, the following precautions should be taken:
- Selection of punch should be made according to the make-up of the job or metal.
- A light hammer should be used for a light punch.
- Do not use an ordinary punch or a hard metal.
- Use a punch after seeing its angle.
- If the point of the punch is damaged, it should be repaired and then the punch should be used.
- Hollow punch should not be used on thick sheets.
By using the punch in your workshop you can create holes in a variety of shapes. Punching is a cost-effective process for making holes in metal workpieces. Now that we know everything about punches but if you have any doubts you can ask in the comments.
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