INFORMATION SHEET
TRADE : OUTCOME No: LESSON No:
DATE : TIME :
TITLE : Reamers,tappers and dies.
OBJECTIVES/TOPICS : At the end of this lesson you shall be able to
• Explain reaming and tapping.
• Explain the classification of dies.
• Explain different types of tapers, reamers and dies.
• Explain the use of different types of tapers, reamers and dies.
Descriptions:
Tap :
A tap has threads like a bolt.It has three to four flutes cut across the threads. It can cut threads on
the inside of a hole. The flutes on the threads form the cutting edges. It is a multi point cutting
tool. It will dig into the walls of the hole as the lower part of the tap is slightly tapered. The shank
of the tap is square shaped to enable it to be held by a tap wrench.
Tapping is the operation of cutting internal threads by means of a cutting tool called
‘tap’. Tapping in a drilling machine may be performed by hand or by power. When the tap is
screwed into the hole, it removes metal and cuts internal threads which will fit into external
threads of the same size.
Taper Tap
This tap is tapered off for 8 to 10 threads, and is used first, cutting to the full thread gradually.
Intermediate Tap
This tap usually has three or four threads chamfered. The second tap can finish a through hole.
Plug Tap
This tap has a full sized, untapered thread to the end, and is the main finishing tap. In the case of a
blind hole, a plug tap must be used.
Reamer:
The tool used for enlarging and finishing a previously drilled hole is known as a reamer.
It is a multi tooth cutter and removes smaller amount of material. It gives a better fnish and
accurate dimension.
The size of hole made by drilling may not be accurate and the internal surface will not
be smooth. Reaming is an accurate way of sizing and finishing a hole which has been
previously drilled by a multi point cutting tool known as reamer.The surface obtained by
reaming will be smoother and the size accurate. The speed of the spindle is made half that of
drilling. Reaming removes very small amount of metal ( approx 0.375 mm). In order to finish
a hole and bring it to the accurate size, the hole is drilled slightly undersize.
Types of Reamers:
There are following types of reamers:
· Hand Reamer
· Machine Reamer
· Chucking Reamer
· Fluting Reamer
· Expanding Reamer
· Adjustable Reamer
· Shell Reamer
Dies:
A die cuts external (male) threads, which may be right or left handed. A dies is made of high quality
tool steel, suitably heat treated.
Types of dies:
The dies may be classified according to the type of press operation and according to the
method of operation.
According to type of press operation:
According to this criterion , the dies may be classified as cutting dies and forming dies.
1: Cutting Dies:
These dies are used to cut the metal. They utilize the cutting or shearing action. The
common cutting dies are : blanking dies , perforating dies , notching dies , trimming ,
shaving and nibbling dies.
2: Forming Dies:
These dies change the appearance of the blank without removing any stock. Theses dies
include bending, drawing and squeezing dies etc.
According to the method of operation:
According to this criterion, the dies may be classified as : single operation or simple
dies , compound dies , combination dies , progressive dies , transfer dies and multiple
dies.
Questions:
REFERENCE :.
