CIPET- DPMT III semester book
SEMESTER – III
MT 303 – MACHINE SHOP TECHNOLOGY - II
MT 303 – MACH
INE SHOP TE
Unit I Milling Machines (80 Hours)
Unit -II Surface Grinding machine - 20 hour
General use of surface grinding machines, Parts of surface grinding machines and their functions, Types and working principle - wet grinding and dry grinding, work and tool holding devices, grinding wheels – abrasives, bonds, grit, grade and structure of wheels – wheel shapes and sizes – mounted wheels – standard marking system – selection of grinding wheels – mounting the grinding wheels – glazing and Wheel loading – dressing and truing of grinding wheels – balancing of grinding wheels – diamond wheels - types and uses – speed and feed parameters – attachments –Plain surface- taper grinding – job accuracy – maintenance and safety.
CHNOLOGY -
General use of surface grinding machines, Parts of surface grinding machines and their functions, Types and working principle - wet grinding and dry grinding, work and tool holding devices, grinding wheels – wheel shapes and sizes – mounted wheels – standard marking system – selection of grinding wheels - balancing of grinding wheels – diamond wheels - types and usage – speed and feed parameters – attachments – concept of spark out – external and internal grinding- taper grinding – job accuracy – maintenance and safety.
Unit IV Tool and Cutter Grinder (16 Hours)
Types and working principle of Tool and Cutter Grinding Machine-Use of cutter grinding accessories and attachments-Nomenclature of Single and Multipoint Cutting ToolsSelections and Specification of Grinding Wheel for Cutter Materials-Method of Setting, Balancing, Truing, Dressing of Grinding Wheel -Procedure of forming of Grinding Wheels for sharpening of lathe & milling cutters.
Unit 1 : milling machine
Tage: milling machine,
About : milling machine
Milling is the machining process of using rotary cutters to remove material from a workpiece by advancing (or feeding) in a direction at an angle with the axis of the tool.It covers a wide variety of different operations and machines, on scales from small individual parts to large, heavy-duty gang milling operations. It is one of the most commonly used processes in industry and machine shops today for machining parts to precise sizes and shapes.
Milling can be done with a wide range of machine tools. The original class of machine tools for milling was the milling machine (often called a mill). After the advent of computer numerical control (CNC), milling machines evolved into machining centers (milling machines with automatic tool changers, tool magazines or carousels, CNC control, coolant systems, and enclosures), generally classified as vertical machining centers (VMCs) and horizontal machining centers (HMCs). The integration of milling into turning environments and of turning into milling environments, begun with live tooling for lathes and the occasional use of mills for turning operations, led to a new class of machine tools, multitasking machines (MTMs), which are purpose-built to provide for a default machining strategy of using any combination of milling and turning within the same work envelope.
about milling machine video
MT 303 – MACHINE SHOP TECHNOLOGY - II
Milling Machine: Parts and Working
Milling is a mechanical machine which is used to machined unsymmetrical job. It is widely used in tool and die making industries. It is a versatile machine. It can perform all operations like turning, facing, drilling, shaping, grooving, etc.
Milling Machine Parts:
There are mostly two types of milling machine used in mechanical industries. First one is horizontal milling machine and other one is vertical milling machine. The basic parts of these machine described as follow.
Base:
It is the foundation part of a milling machine. All other parts are jointed on it. It carries the entire load so it should have high compressive strength so it is made by cast iron. It also works as reservoir of cutting fluid.
Column:
Column is another foundation part of milling machine. It is mountain vertically on the base. It supports the knee, table etc. Work as housing for the all the other driving member.it is a hollow member which contains driving gears and sometimes motor for spindle and the table.
Knee:
Knee is the first moving part of milling machine. If is mounted on the column and moves along the slideways situated over the column. It is made by cast iron and moves vertically on slideways It moves up and down on sideways which change the distance between tool and workpiece It is driven by mechanically or hydraulically.
Saddle:
It is placed between table and the knee and work as intermediate part between them. It can moves transversally to the column face. It slides over the guide ways provided situated on the knee which is perpendicular to the column face. The main function of it is to provide motion in horizontal direction to work piece. It is also made by cast iron.
Table:
Table is situated over the knee. It is the part of machine which holds the work piece while machining. It is made by cast iron and have T slot cut over it. The work piece clamp over it by using clamping bolts. The one end of clamping bolt fix into this slot and other is fix to work piece which hold the work piece. It can provide three degree of freedom to work piece.
- It provides vertical motion by moving the knee up and down.
- It provides horizontal motion by the feed screw.
- It provides horizontal (transverse) motion by moving the saddle.
Overhanging arm:
It is situated over the column on horizontal milling machine. It is overhang over the column surface and other end supports the arbor. It is made by cast iron.
Spindle:
Spindle is the main part of the machine which hold tool at right place in vertical milling machine and hold arbor in horizontal milling machine. It is a moving part which is in rotary motion. It is motor driven and drives the tool. It has a slot on the front end of it. The cutting tool fix in that slot.
Arbor:
It is a mechanical part on which is used as extension part of the spindle in horizontal milling machine. It is fitted on the spindle whenever required. It holds the tool and moves it in correct direction.
Arbor Supports:
This are used to support arbor at right place. One end of this support is jointed at the overhanging arm and another is jointed with arbor.
Milling head:
It is upper section of vertical milling machine. It consist spindle, driving motor and other controlling mechanism.
Ram:
Ram is work as overhanging arm in vertical milling machine. One end of the arm is attached to the column and other end to the milling head.
Working of Milling Machine:
A milling is a versatile machine which is used to form different shapes by metal cutting. The working of milling machine is as follow.
1. First the cutting tool is set at the arbor which is connected to the spindle.
2. The knee is moved downward.
3. Now the work piece is clamped on the table by using clamping screw.
4. All the controlling points are set to zero like knee position, saddle position etc.
5. Now the spindle starts to rotate which further rotates the cutting tool.
6. As the tool is moving, we move the work piece as required by moving the knee, saddle and table.
7. The controlling axis move the work piece and cut the desire shape on it. The tool remains stationary and only in rotary motion.
unit-II Surface Grinding machine
unit-II Surface Grinding machine
Construction (Main Parts of Horizontal Reciprocating Table Surface Grinder) Points :Construction (Main Parts of Horizontal Reciprocating Table Surface Grinder), Base, Table, Wheel Head, Coolant System, Capacity, Wheels The major parts of the Planer type horizontal-spindle surface grinder and are briefly discussed below.
1. Base The base of the horizontal surface grinder has a column at the back for supporting the wheel-head. The saddle which supports the table is mounted on carefully machined ways at the front of the machine.
2. Table The table on most grinders is similar to the table on the milling machine. It is fitted to the saddle by carefully machined ways. It can be moved right or left traverse travel under the grinding wheel. This kind of table' is called reciprocating. The table carries adjustable reversing dogs which may be set to limit table travel. Hand table feeds can be used as well as automatic power feeds. On some machines, the table can be moved in or out from the vertical column which supports the wheel-head. This movement is known as cross feed. Slide ways. On other machines, the wheel and driving motor (wheel-head) move on cross-slide ways.
3. Wheel Head The wheel-head is mounted on the column. It moves on carefully machined way by which it can be raised or lowered. A hand wheel which turns a lead screw is used to move it up and down on the- column. A spindle for revolving the grinding wheel is mounted in the head in. a horizontal position. Hence machine is called horizontal. The heart of any precision grinding machine is the grinding wheel spindle and bearing.
Any wear in the bearings that permits the spindle to vibrate will make the machine useless for precision work. A disk wheel is mounted on the horizontal spindle. The: wheel grinds the work-piece as it feeds and reciprocates under the wheel.
An electric motor is built into the machine to furnish power’ to turn the grinding wheel. The wheel is usually driven by pulleys and belts or direct spindle drive.
4. Coolant System A coolant must be used to regulate the temperature of the work. The coolant is directed to the work by pipes from a pump and a tank.
5. Capacity Grinders are described in terms of work capacity. This is usually given as the maximum working space provided by the work-holding device, which usually is the magnetic chuck. A machine size of 152.4 mm by 457.2 mm (6 inches by 18 inches) designates the dimensions of the working area of the chuck or table.
6. Wheels The wheels used in the horizontal machine are usually plain wheels which cut on the periphery in grinding shoulders; a recessed wheel may be used. In grinding V’s and other shapes, wheels with formed edges are used.
CHNOLOGY -
IDENTIFYING MACHINE PARTS AND THEIR FUNCTIONS
On the center-type cylindrical grinder (Figure L-110), the workpiece is mounted between centers much as it would be in the lathe. The plain cylindrical grinder (Figure L-111) has a fixed wheelhead that cannot be swiveled, only moved toward or away from the center axis of the workpiece. The table can be swiveled to permit the grinding of tapered workpieces.
On the universal cylindrical grinder (Figure L-112), both the wheelhead and table may be swiveled for taper grinding. All possible motions are illustrated in Figure L-113.
On the universal cylindrical grinder (Figure L-112), both the wheelhead and table may be swiveled for taper grinding. All possible motions are illustrated in Figure L-113.
Major Parts of the Universal Center-Type Cylindrical Grinder Major parts of the machine include the bed, slide, swivel table, headstock, footstock, and wheelhead.
Bed The bed is the main structural component and is responsible for the rigidity of the machine tool. The bed supports the slide, which in turn supports the swivel table.
Slide and Swivel Table The slide carries the swivel table and provides the traverse motion to carry the workpiece past the wheel. The swivel table is mounted on the slide and supports the headstock and footstocks. The swivel table has graduations for establishing taper angles.
Headstock The headstock (Figure L-114) mounts on the swivel table and is used to support one end of the workpiece.
The headstock also provides the rotating motion for the workpiece. The headstock spindle is typically designed to accept a chuck or face plate. The headstock center is used when workpieces are mounted between centers. Variable headstock spindle speed selection is also available. For the most precise cylindrical grinding, the headstock center is held stationary while the driving plate that rotates the part rotates concentric to the dead center. This procedure eliminates the possibility of duplicating headstock bearing irregularities into the workpiece. For parts that can tolerate minor runout errors, it is preferable to have the center turn with the driving plate.
Footstock The footstock (Figure L-115) is also mounted on the swivel table and supports the opposite end of a workpiece mounted between centers. The footstock center does not rotate. It is spring loaded and retracted by a lever.
This permits easy installation and removal of the workpiece.Compression loading on the spring is adjustable, and the footstock spindle typically can be locked after it is adjusted.
Figure L-115 Typical footstock. The lever on top of the footstock retracts the work center so that the workpiece can be mounted on the grinder. The spring (right end of sketch) provides tension to hold the workpiece in place.
The footstock assembly is positioned on the swivel table at whatever distance is needed to accommodate the length of
the workpiece.
Wheelhead The wheelhead, located at the back of the machine, contains the spindle, bearings, drive, and main motor.
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Unit IV Tool and Cutter Grinder
A tool and cutter grinder is used to sharpenmilling cutters and tool bits along with a host of other cutting tools.
It is an extremely versatile machine used to perform a variety of grinding operations: surface, cylindrical, or complex shapes. The image shows a manually operated setup, however highly automated Computer Numerical Control (CNC) machines are becoming increasingly common due to the complexities involved in the process.
The operation of this machine (in particular, the manually operated variety) requires a high level of skill. The two main skills needed are understanding of the relationship between the grinding wheel and the metal being cut and knowledge of tool geometry. The illustrated set-up is only one of many combinations available. The huge variety in shapes and types of machining cutters requires flexibility in usage. A variety of dedicated fixtures are included that allow cylindrical grindingoperations or complex angles to be ground. The vise shown can swivel in three planes.
The table moves longitudinally and laterally, the head can swivel as well as being adjustable in the horizontal plane, as visible in the first image. This flexibility in the head allows the critical clearance angles required by the various cutters to be achieved
Today's tool and cutter grinder is typically a CNC machine tool, usually 5 axes, which produces endmills, drills, step tools, etc. which are widely used in the metal cutting and woodworking industries.
CNC TOOLS
CNC TOOLS
Modern CNC tool and cutter grinders enhance productivity by typically offering features such as automatic tool loading as well as the ability to support multiple grinding wheels. High levels of automation, as well as automatic in-machine tool measurement and compensation, allow extended periods of unmanned production. With careful process configuration and appropriate tool support, tolerances less than 5 micrometres (0.0002") can be consistently achieved even on the most complex parts.
Apart from manufacturing, in-machine tool measurement using touch-probe or laser technology allows cutting tools to be reconditioned. During normal use, cutting edges either wear and/or chip. The geometric features of cutting tools can be automatically measured within the CNC tool grinder and the tool ground to return cutting surfaces to optimal condition.
Significant software advancements have allowed CNC tool and cutter grinders to be utilized in a wide range of industries. Advanced CNC grinders feature sophisticated software that allows geometrically complex parts to be designed either parametrically or by using third party CAD/CAM software. 3D simulation of the entire grinding process and the finished part is possible as well as detection of any potential mechanical collisions and calculation of production time. Such features allow parts to be designed and verified, as well as the production process optimized, entirely within the software environment.
Tool and cutter grinders can be adapted to manufacturing precision machine components. The machine, when used for these purposes more likely would be called a CNC Grinding System.
CNC TOOLS:
CNC Grinding Systems are widely used to produce parts for aerospace, medical, automotive, and other industries. Extremely hard and exotic materials are generally no problem for today's grinding systems and the multi-axis machines are capable of generating quite complex geometries
Today's tool and cutter grinder is typically a CNC machine tool, usually 5 axes, which produces endmills, drills, step tools, etc. which are widely used in the metal cutting and woodworking industries.
Modern CNC tool and cutter grinders enhance productivity by typically offering features such as automatic tool loading as well as the ability to support multiple grinding wheels. High levels of automation, as well as automatic in-machine tool measurement and compensation, allow extended periods of unmanned production. With careful process configuration and appropriate tool support, tolerances less than 5 micrometres (0.0002") can be consistently achieved even on the most complex parts.
Apart from manufacturing, in-machine tool measurement using touch-probe or laser technology allows cutting tools to be reconditioned. During normal use, cutting edges either wear and/or chip. The geometric features of cutting tools can be automatically measured within the CNC tool grinder and the tool ground to return cutting surfaces to optimal condition.
Significant software advancements have allowed CNC tool and cutter grinders to be utilized in a wide range of industries. Advanced CNC grinders feature sophisticated software that allows geometrically complex parts to be designed either parametrically or by using third party CAD/CAM software. 3D simulation of the entire grinding process and the finished part is possible as well as detection of any potential mechanical collisions and calculation of production time. Such features allow parts to be designed and verified, as well as the production process optimized, entirely within the software environment.
Tool and cutter grinders can be adapted to manufacturing precision machine components. The machine, when used for these purposes more likely would be called a CNC Grinding System.
CNC Grinding Systems are widely used to produce parts for aerospace, medical, automotive, and other industries. Extremely hard and exotic materials are generally no problem for today's grinding systems and the multi-axis machines are capable of generating quite complex geometries.
Radius grinder
A radius grinder (or radius tool grinder) is a special grinder used for grinding the most complex tool forms, and is the historical predecessor to the CNC tool and cutter grinder. Like the CNC grinder, it may be used for other tasks where grinding spherical surfaces is necessary. The tool itself consists of three parts: The grinder head, work table, and holding fixture. The grinder head has three degrees of freedom. Vertical movement, movement into the workpeice, and tilt. These are generally set statically, and left fixed throughout operations. The work table is a T-slotted X-axis table mounted on top of a radial fixture. Mounting the X axis on top of the radius table, as opposed to the other way around, allows for complex and accurate radius grinds. The holding fixtures can be anything one can mount on a slotted table, but most commonly used is a collet or chuck fixture that indexes and has a separate Y movement to allow accurate depth setting and endmill sharpening. The dressers used on these grinders are usually quite expensive, and can dress the grinding wheel itself with a particular radius
The D-bit grinder is a tool bit grinder that specializes in the grinding of D-bit cutters forpantograph milling machines. Pantographs are a variety of milling machine used to create cavities for the dies used in the molding process, they are being rapidly replaced byCNC machining centers.
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