Page 140 - CITS - Fitter - Trade Theory

FITTER - CITS

MODULE 8

LESSON 22 : Introduction to broaching machine

Objectives

At the end of this lesson you shall be able to
• define the broaching machine and its types
• state the process of broaching
• state the different categorized of broaching machine on their design and functionality
• state the safety precaution while operating broaching machine.

• Introduction of broaching machine: Broaching is a machining process that uses a toothed tool called a
Broach, to remove material.
There are two types of broaching machine: -
1 Linear machine
2 Rotary machine
1 Linear machine:
A linear rotating broaching machine, also known as a rotary broaching machine or wobble broaching machine,
is a type of broaching machine that combines linear and rotational motion to perform the broaching operation.
In this type of machine, the broach tool is held stationary while the workpiece is rotated and advanced linearly
against the broach. The broach tool has a slightly offset axis compared to the workpiece rotation axis, causing it
to wobble as it cuts, hence the term “wobble broaching.”
This method is commonly used for producing hexagonal or other polygonal shapes on the end of cylindrical
workpieces, such as bolts or shafts, with high precision and efficiency. It’s often preferred for its ability to create
complex shapes with minimal setup time and tool wear.
2 Rotary machine:
A rotary broaching machine, also known as a rotary or rotary table broaching machine, is a type of broaching
machine that utilizes rotary motion to perform the broaching operation. In this machine, the broach tool is mounted
on a spindle or tool holder that rotates at high speed while being pressed into the workpiece.
The workpiece is typically held stationary or may rotate at a slower speed. As the broach tool rotates, it cuts into
the workpiece, producing the desired shape or profile. Rotary broaching is commonly used for creating internal or
external features such as splines, keyways, hexagons, squares, or other polygonal shapes.
Rotary broaching machines are valued for their ability to produce precise and accurate features quickly, making
them popular in manufacturing applications where high precision and efficiency are required.
Process: -
The broaching process involves using a broach tool—a long, multi-toothed cutting tool—to remove material in a
controlled manner. Here’s an overview of the broaching process:
1 Setup: The workpiece is securely clamped into the broaching machine or fixture. Proper alignment and posi-
tioning are crucial for accurate cutting.
2 Selection of Broach Tool: The appropriate broach tool is selected based on the desired shape or profile to be
machined. Broaches come in various types, including keyway broaches, spline broaches, and surface broaches.
3 Insertion of Broach Tool: The broach tool is inserted into the broaching machine’s spindle or holder. In some
cases, the workpiece may be moved against the stationary broach, while in others, the broach rotates against
the stationary workpiece.
4 Engagement: The broach tool engages with the workpiece, starting the cutting process. The teeth of the broach
progressively remove material with each pass.
5 Cutting Stages: The broaching process typically involves multiple cutting stages or passes. Each pass removes
a predetermined amount of material until the final desired shape or depth is achieved.

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CITS : CG & M - Fitter - Lesson 21