Chapter 1 - Machine Tools.ppt 96l1r

INTRODUCTION TO MACHINE TOOL DESIGN

By Prof. P. Laxminarayana MED,UCE,OU

Processing  Before we get started, realize that tools and machines are used in three major types of processing:  Material Processing  Energy Processing  Information Processing  For the purposes of this Unit, we will be looking at tools and machines used in material processing .

Machine Tools  All specialists would be lost without their tools of trade. Imagine a dentist without a dental drill or bricklayer without a tape measure!  It is the same in engineering and technology.  Without the proper tools, tasks cannot be accomplished correctly.  Within this unit, we are going to discuss some common machine tools that are used in the field and the safety precautions behind them

Machining  It has already been stated that machines are artifacts that amplify the speed, amount, or direction of a force. They transmit or change the application of power, force, or motion.  Specifically, machine tools are machines that are used to make other machines.  Machining is a separating process based on the motion of a tool against a work piece .

Characteristics  Machine tools have some common characteristics:

 A method of cutting materials to desired shape and size.  A series of motions between the material and the tool, causing the tool to cut the material.  of the tool and the work piece

Cutting Tool  Most cutting actions require a cutting tool.  Two basic types of cutting tools are used in all hand tools and

machines. They are single-point and multiple-point.  The single-point tool is the simplest cutting device available. It has a cutting edge on the end or along the edge of a rod. Common single-point tools include knives, chisels, and wood planes.  The multiple-point tool has a series of single-point tools arranged on a cutting device. Most often, these single-points are arranged in a pattern. For example, a circular saw has teeth evenly spaced around the circumference of the blade (Wright, 2004).

Motion  Cutting motion is the action that causes material to be removed from the work. It causes the excess material to be cut away.  Feed motion is the action that brings new material into the cutter. It allows the cutting action to be continuous.  Cutting and feed motions can be:  Rotating – uses round cutters or spins the work around an axis  Linear – moves a cutter or work in one direction along a straight line  Reciprocating – moves the tool or the work back and forth (

 The final element present in all machine tools is for the tool and the work piece.  Chucks are attachments used to hold and rotate drills and router bits.  Arbors are spindles or shafts that are used to hold table saw blades and milling putters

Types of Machine Tools  Hundreds of different machine tools exist, however they can be grouped into six categories:  Turning Machines  Sawing Machines  Drilling Machines  Shaping Machines  Planing Machines  Grinding Machines

Turning Machines  Turning machines use a process in which a work piece is held or rotated on an axis.  This action is produced on machines called lathes.  All lathes produce their cutting motion by rotating the work piece.  Linear movement of the tool generates the feed motion, and is primarily used to machine wood and metal

Sawing Machines • Sawing Machines use teeth on a blade to cut material to a desired size and shape. • Sawing Machines can be grouped according to the type of blade they use and the methods used to produce the cutting action. This grouping identifies three basic types of saws: • Circular Saws- use a blade in the shape of a disk with teeth arranged around the edge. • Band Saws – use a blade made of a continuous strip (or band) of metal with teeth on one or more edges. • Scroll Saws use a straight blade that is a strip of metal with teeth on one edge

Drilling Machines • Drilling machines produce or enlarge holes using a rotating cutter. • Generally, the cutting motion is produced as the drill or bit rotates

Other Machines • Shaping and planing machines are two metal working machine tools that produce flat surfaces. They should not be confused with the wood working shaping and planing machines which operate on the same principles as sawing machines. • Both the metal shaper and the metal planer use single point tools and reciprocating motion to produce the cut. • Grinding machines use bonded abrasives (grinding wheels) to cut the material. • These wheels have random cutting surfaces that remove the material in the form of very small chips.