NAME OF LABORATORY: METAL CUTTING & CNC
LAB SUBJECT CODE: ME-603
NAME OF DEPARTMENT: MECHANICAL ENGINEERING
LAB MANUAL
OF
METAL CUTTING
AND
CNC MACHINES
(ME-603)
PREPARED BY:
DEEPANJALI GIRI
ASST. PROFESSOR
MECHANICAL ENGG. DEPTT.
LIST OF THE EXPERIMENTS
SNO / NAME OF THE EXPERIMENT / PAGE NOFROM / TO
1. / Study Of Lathe Machine With Various Operations.
2. / Study Of Types Of Grinding Machine.
3. / Study Of Horizontal And Vertical Milling Machine.
4. / Study Of Radial Drilling Machine.
5. / Study Of Principle Of Broaching Machine.
6. / Study Of Shaper And Quick Return Mechanism.
7. / Study Of Gear Cutting On Milling Machine.
8. / Study Of Gear Cutting Methods.
9. / Study Of Mechatronics.
10.
11
EXPERIMENT NO. 1
Object: Study of Lathe Machine with various Operations.
THEORY:
A lathe is a machine tool which turns cylindrical material, touches a cutting tool to it, and cuts the material. The lathe is one of the machine tools most well used by machining.
Lathes are machine tools which turn or rotate a lump of material to carry out various operations like drilling, facing, cutting, threading, reaming, grooving, sanding, parting, knurling, and boring along with the usage of cutting tools which are applied to the material to produce an object. The finished product will have symmetry about a rotational axis. The cutting tool moves parallel or perpendicular with respect to workpiece axis to create the desired shape. The typical lathe consists of a headstock, where the spindle is connected to hold the work piece to be machined, gears and speed changing levers. Opposite end of headstock is the tailstock which is a tool holding device. The bed is the base of the lathe which is connected with headstock and allows carriage and tailstock for parallel alignment. A compound rest carries a tool post on which the toolbit is mounted moves along lead screw as shown in Figure no.1, a material is firmly fixed to the chuck of a lathe. The lathe is switched on and the chuck is rotated. And since the table which fixed the byte can be moved in the vertical direction, and the right-and-left direction by operating some handles shown in Fig. 3. It touches a byte's tip into the material by the operation, and make a mechanical part.
Lathe head stock
Three Important Elements
In order to get an efficient process and beautiful surface at the lathe machining, it
is important to adjust a rotating speed, a cutting depth and a sending speed. Please note that the important elements can not decide easily, because these suitable values are quiet different by materials, size and shapes of the part.
Rotating Speed
It expresses with the number of rotations (rpm) of the chuck of a lathe. When the rotating speed is high, processing speed becomes quick, and a processing surface is finely finished. However, since a little operation mistakes may lead to the serious accident, it is better to set low rotating speed at the first stage.
Fig. 3.Lathe principal
Cutting Depth
The cutting depth of the tool affects to the processing speed and the roughness of surface. When the cutting depth is big, the processing speed becomes quick, but the surface temperature becomes high, and it has rough surface. Moreover, a life of byte also becomes short. If you do not know a suitable cutting depth, it is better to set to small value.
Sending Speed (Feed)
The sending speed of the tool also affects to the processing speed and the roughness of surface. When the sending speed is high, the processing speed becomes quick. When the sending speed is low, the surface is finished beautiful. There are 'manual sending' which turns and operates a handle, and 'automatic sending' which advances a byte automatically. A beginner must use the manual sending. Because serious accidents may be caused, such as touching the rotating chuck around the byte in automatic sending,
Cutting Tools for Lathe
There are various kinds of the cutting tools for a lathe. We must choose them by the materials and shape of a part. Three typical cutting tools are introduced in follows. Then we consider what is an easy process or a hard process.
Form of Typical Cutting Tools
Figure 5(a) shows the most well-used cutting tool called a side tool. It can process to cut an outside surface and an edge surface. Since the material is set at the right of lathe, then this tool can only cut the right of the material.
The cutting tool shown in Figure 5(b) is used at parting and grooving processes. Its pointed end is slim, then it is too weak. Don't add a strong side-force to the tool. This tool must send vertical direction only.
Fig no.5.Types of tools
The cutting tool shown in Figure 5(c) is called a boring bar. It is used to cut at an inside surface. It can make a big hole, which cannot be process by a drill, and an high accurate hole.
Advantages
Advantages of lathes are:
· Can perform various operations in a single lathe machine
· Can be operated along with other machine tools like drill press
· Workpieces of larger diameter can be processed in a lathe
· Good finishing of materials.
Applications
CNC lathes are widely used lathe machines in most manufacturing industries in order to perform lathe operations effectively thus reducing productivity time. Other widely used applications are in automobiles, electrical, electronics, defense, and escalator industries.
EXPERIMENT NO. 2
Object: Study of types of Grinding Machine.
Introduction:
The grinder is a machine that is used for fine surface finishing and the amount of material removed rarely exceeds a few thousands of an inch. These machines have been developed over the years to satisfy specific needs of the industry it serves, so grinding has become specialized, as has turning and milling. The most common types of grinders are the surface grinder, the universal tool and cutter grinder, and the cylindrical grinder
Surface grinding is probably the most fundamental of operations. Most shops have a surface grinder even if they don't have a universal cutter grinder of a cylindrical grinder. The basic machine has grinding wheel above the work area which can be fed downward in very small increments into a work piece which is being moved to the left and the right and in and out. This allows the wheel to contact all areas of the surface of the work piece. The grinder is usually equipped with a magnetic plate used to hold the work piece . It is sometimes referred to as a magnetic chuck, although it does not look anything like a lathe chuck . The magnetic chuck holds magnetic materials only. However steel clamps (a magnetic material) can be used to laterally clamp non-magnetic materials for surface grinding.
Theory:
The grinding machine consists of a power driven grinding wheel spinning at the required speed (which is determined by the wheel’s diameter and manufacturer’s rating, usually by a formula) and a bed with a fixture to guide and hold the work-piece. The grinding head can be controlled to travel across a fixed work piece or the workpiece can be moved whilst the grind head stays in a fixed position. Very fine control of the grinding head or tables position is possible using a vernier calibrated hand wheel, or using the features of numerical controls.
Grinding machines remove material from the workpiece by abrasion, which can generate substantial amounts of heat; they therefore incorporate a coolant to cool the workpiece so that it does not overheat and go outside its tolerance. The coolant also benefits the machinist as the heat generated may cause burns in some cases. In very high-precision grinding machines (most cylindrical and surface grinders) the final grinding stages are usually set up so that they remove about 200nm (less than 1/100000in) per pass - this generates so little heat that even with no coolant, the temperature rise is negligible.
Types:
These machines include the:Belt grinder, which is usually used as a machining method to process metals and other materials, with the aid of coated abrasives. Sanding is the machining of wood; grinding is the common name for machining metals. Belt grinding is a versatile process suitable for all kind of applications like finishing, deburring, and stock removal.
· Bench grinder, which usually has two wheels of different grain sizes for roughing and finishing operations and is secured to a workbench. It is used for shaping tool bits or various tools that need to be made or repaired. Bench grinders are manually operated.
· Cylindrical grinder which includes the centerless grinder. A cylindrical grinder may have multiple grinding wheels. The workpiece is rotated and fed past the wheel/s to form a cylinder. It is used to make precision rods.
· Surface grinder which includes the wash grinder. A surface grinder has a "head" which is lowered, and the workpiece is moved back and forth past the grinding wheel on a table that has a permanent magnet for use with magnetic stock. Surface grinders can be manually operated or have CNC controls.
· Tool and cutter grinder and the D-bit grinder. These usually can perform the minor function of the drill bit grinder, or other specialist toolroom grinding operations.
· Jig grinder, which as the name implies, has a variety of uses when finishing jigs, dies, and fixtures. Its primary function is in the realm of grinding holes and pins. It can also be used for complex surface grinding to finish work started on a mill.
· Gear grinder, which is usually employed as the final machining process when manufacturing a high precision gear. The primary function of these machines is to remove the remaining few thousandths of an inch of material left by other manufacturing methods (such as gashing or hobbing).
Fig no.1. Grinding operation
Grinding spindles Characteristics
Some important characteristics common to many grinding spindles are as follows:
· In most grinding spindles, there is an oil/air mist lubrication system with an effective heat dissipation method which helps in simplifying the spindle configuration.
· There is the standard spindle range for vertical grinding and horizontal grinding which is developed to enable vertical applications and horizontal applications.
· There is also spindle range for internal grinding and motorized main spindle ranges.
· Grinding spindles include special solutions to prevent or avoid dirt collection inside.
· The spindle design also considers the different vibration behavior of a rotating shaft from vertical and horizontal positions etc.
Grinding spindles: Uses
The grinding efficiency is measured in terms of material removal rate which is attained by employing ultra high wheel speeds. For any ultra high speed grinding machine tool, the spindle is a key component. The various uses of grinding spindles are given below:
· The grinding spindle is used for roughing and finishing flat, cylindrical and conical surfaces.
· The grinding spindle is used for finishing internal cylinders or bores.
· It helps in forming and sharpening cutting tools.
· It also helps in snagging or removing rough projections from castings and stampings.
· Another important task of grinding spindles is to cleaning, polishing and buffing surfaces.
Types of grinding machine spindles
All spindles are usually classified into three main categories-high frequencies, belt driven or motorized. Other popular types of grinding spindles are:
· Internal grinding spindles: Internal grinding is considered to be the most challenging of all grinding applications. Internal grinding means the precision grinding of the inside surface of the hole in a work piece, enlarging or finishing of the cylindrical opening or inside diameter in a workpiece.
· External grinding spindles: External grinding, which is also important to many manufacturing organizations, refers to grinding of the outer surface of a workpiece.
· Horizontal grinding spindles: Horizontal grinding spindles are designed to grind advanced materials, including wafer backside grinding operations, achieving a high degree of flatness while at the same time optimizing surface finishes. They are so called because the grinding process takes place in a horizontal way. On machines with horizontal spindle the motor-driven spindles are horizontal. In such machines the parts are guided through the grinding wheels vertically.
· Vertical grinding spindles: Vertical grinding , as the name suggests, fixes the workpiece on a rotary chuck in the machine base , similar to the orientation of the workpiece on a vertical lathe. The vertical grinding spindle travels up and down and side to side and at times may also swivel from above the workpiece. On machines with vertical spindle, the motor-driven spindles are vertical and the parts are guided through the grinding wheels horizontally.
EXPERIMENT NO. 3
Object: Study of Horizontal and Vertical Milling Machine
Horizontal milling machine:- The main parts of the horizontal mill are the; base, column, knee, saddle, table, spindle, overarm and arbor supports. Below you will find illustrations of a horizontal milling machines and it’s parts. Study these parts and be ready to answer questions concerning their names location and uses.
Column-The column of the milling machine, along with the base, are the major structural components. They hold, align, and support the rest of the machine.
Table-Holds and secures the workpiece for machining.
Saddle-The saddle is attached to the knee. The saddle provides the in and out, or Y axis table travel.
Knee-The knee supports the saddle and the table. The knee can be moved up and down for workpiece positioning.
Base- The base of the milling machine, along with the column, are the major structural components. They hold, align, and support the rest of the machine.
Spindle-The spindle holds the tool and provides the actual tool rotation.
Spindle Reverse Lever-The position of this lever determines the spindle direction. The three positions of the handle are; In, Middle, and Out. The middle position is the neutral position. Never move the spindle reverse lever when the spindle is turning.