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Workshop Technology ii

Workshop Technology ii. Made By Ankit Panghal. Chapter No. -1 Cutting Tools And Cutting Tool Materials. Introduction.

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Workshop Technology ii

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  1. Workshop Technology ii Made By AnkitPanghal

  2. Chapter No. -1 Cutting Tools And Cutting Tool Materials

  3. Introduction • Cutting tool is any tool that is used to remove material from the workpieceby means of shear deformation. Cutting may be accomplished by single-point or multipoint tools. • Single-point tools are used in turning, shaping, plaining and similar operations, and remove material by means of one cutting edge. • Milling, grinding and drilling tools are often multipoint tools. Each grain of abrasive functions as a microscopic single-point cutting edge and shears a tiny chip. • Cutting tools must be made of a material harder than the material which is to be cut, and the tool must be able to withstand the heat generated in the metal-cutting process. Also, the tool must have a specific geometry, with clearance angles designed so that the cutting edge can contact the workpiece without the rest of the tool dragging on the workpiece surface.

  4. Types of Cutting Tool • Single Point Cutting Tool – The cutting tools terminating in a single point are termed as a single point cutting tools. • Multi Point Cutting Tool – The Cutting tools being composed of more than single point are termed as multipoint cutting tools. The Cutting tools may also be classified according to the motion as follows:- • Linear cutting tools - Tools bits, Broaches, Planing, shaping tools etc. • Rotary cutting tools- Grinding Wheel, Taps and dies, Milling cutters, • Linear and Rotary Motion Tools- Drilling, Honing tools, Boring heads etc.

  5. Single-Point Cutting Tool Multi-Point Cutting Tool

  6. Various Types Of Single Point Cutting Tools

  7. Important Terms Relating To Single Point Cutting Tool Single Point Cutting Tool

  8. Heat Produce During Metal Cutting

  9. Cutting Tool Materials • Carbon Steels - Carbon steels have been used since the 1880s for cutting tools. However carbon steels start to soften at a temperature of about 180oC. This limitation means that such tools are rarely used for metal cutting operations. Plain carbon steel tools, containing about 0.9% carbon and about 1% manganese, hardened to about 62 Rc, are widely used for woodworking and they can be used in a router to machine aluminium sheet up to about 3mm thick. • High Speed Steel (HSS)- HSS tools are so named because they were developed to cut at higher speeds. Developed around 1900 HSS are the most highly alloyed tool steels. The tungsten (T series) were developed first and typically contain 12 - 18% tungsten, plus about 4% chromium and 1-5% vanadium. Most grades contain about 0.5% molybdenum and most grades contain 4-12% cobalt. Consequently about 95% of all HSS tools are made from M series grades. These contain 5 - 10% molybdenum, 1.5 - 10% tungsten, 1-4% vanadium, 4% Chromium and many grades contain 5 - 10% cobalt. HSS tools are tough and suitable for interrupted cutting and are used to manufacture tools of complex shape such as drills, reamers, taps, dies and gear cutters. Tools may also be coated to improve wear resistance. HSS accounts for the largest tonnage of tool materials currently used. Typical cutting speeds: 10 - 60 m/min.

  10. Carbides - Also known as cemented carbides or sintered carbides were introduced in the 1930s and have high hardness over a wide range of temperatures, high thermal conductivity, high Young's modulus making them effective tool and die materials for a range of applications. The two groups used for machining are tungsten carbide and titanium carbide, both types may be coated or uncoated. Tungsten carbide particles (1 to 5 micro-m) are bonded together in a cobalt matrix using powder metallurgy. The powder is pressed and sintered to the required insert shape.titaniumand niobium carbides may also be included to impart special properties. A wide range of grades are available for different applications. Sintered carbide tips are the dominant type of material used in metal cutting. The proportion of cobalt (the usual matrix material) present has a significant effect on the properties of carbide tools. 3 - 6% matrix of cobalt gives greater hardness while 6 - 15% matrix of cobalt gives a greater toughness while decreasing the hardness, wear resistance and strength. Tungsten carbide tools are carbides tools commonly used for machining steels, cast irons and abrasive non-ferrous materials.

  11. Chapter No. -2 Drilling

  12. Introduction • Drilling: It is an operation-producing hole in solid materials using drill- a rotating cutting tool. • Drills: these are the ends cutting tools designed for drilling. Mainly there are two types- flat drills and twist drills. • Twist drills: These are manufactured by twisting and grounding the tool longitudinally. These help not only for easy drilling but also to remove chips automatically during drilling. These are made from carbon steels and high-speed steels. • Straight shank twist drill: These are also used on portable hand or electric drilling machines. These are held in machines using a chuck and a key. • Tapered shank twist drills: these are used to drill holes from 3 to 100mm diameters. These could be directly inserted into the spindle of the machine by simple thrust with a soft tap.

  13. Classification for drilling machines: • Drilling machines are broadly classified as follows- 1.portable drilling machines 2. Sensitive drilling machines (Bench drilling machine) 3. Up right drilling machines 4. Radial drilling machine. 5. Gang drilling machines. 6. Multiple drill head-drilling machines. 7. Automatic drilling machine.

  14. Bench drilling machine: • These are light duty machines used in small workshops. • Also called Sensitive drilling machines because of its accurate and well balanced spindle. • Holes of diameter 1 mm to 15 mm.

  15. Parts :- • Vertical main column • Base • Moving drill head • Work table • Electric motor • Variable speed gear box and spindle feed mechanism.

  16. Working • Work piece with the exact location marked on it with the centre punch is clamped rigidly on the work table. • spindle axis and center punch indentation are in same line. • Machine is started and drill bit is lowered by rotating feed handle. • Drill bit touches the work and starts removing material.

  17. Disadvantages: • A skilled worker is a must. • Only small size holes can be drilled.

  18. Radial drilling machine

  19. working • Work piece is marked for exact location and mounted on the work table. • Drill bit is then located by moving the radial arm and drill to the marked location. • By starting drill spindle motor holes are drilled.

  20. Drilling machine operation • Reaming • Boring • Counter boring • Counter sinking • Spot facing • Tapping

  21. Reaming • It is a process of smoothing the surface of drilled holes with a tool. • Tool is called as reamer. • Initially a hole is drilled slightly smaller in size. • Drill is replaced by reamer. • Speed is reduced to half that of the drilling.

  22. Reaming

  23. Boring It is process carried on a drilling machine to increase the size of an already drilled hole. Initially a hole is drilled to the nearest size and using a boring tool the size of the hole is increased.

  24. Counter boring This process involves increasing the size of a hole at only one end. Cutting tool will have a small cylindrical portion called pilot. Cutting speed = two-thirds of the drilling speed for the same hole.

  25. Counter sinking This is an operation of making the end of a hole into a conical shape. Cutting speed = half of the cutting speed of drilling for same hole.

  26. Spot facing It is a finishing operation to produce flat round surface usually around a drilled hole, for proper seating of bolt head or nut. It is done using a special spot facing tool.

  27. Tapping Process of cutting internal threads with a thread tool called as tap. Tap is a fluted threaded tool used for cutting internal thread Cutting speed is very slow.

  28. Specification of drilling machines • The maximum diameter of the drill that can be used in that machine. • The maximum size of the work piece that can be worked on in that machine. • Size of the working table. • Number of spindles in that machine. • Power capacity of the machine. • For radial drilling machines, diameter of the column and the length of the arm have to be specified.

  29. Chapter No. -3 Lathe

  30. LATHE MACHINE

  31. INTRODUCTION • Lathe is one of the oldest important machine tools in the metal working industry. A lathe operates on the principle of a rotating work piece and a fixed cutting tool. • The cutting tool is feed into the workpiece, which rotates about its own axis, causing the workpiece to be formed to the desired shape. • Lathe machine is also known as “the mother/father of the entire tool family”.

  32. Types of Lathe • ENGINE LATHE • BENCH LATHE • TOOL ROOM LATHE • AUTOMATIC LATHE • TURRET LATHE • COMPUTER CONTROLLED LATHE

  33. Engine Lathe or Centre Lathe • This term ‘engine’ is associated with the lathe owing to the fact that early lathes were driven by steam engine. It is also called centre lathe. The most common form of lathe, motor driven and comes in large variety of sizes and shapes.

  34. Engine lathes are classified according to the various designs of headstock and methods of transmitting power to the machine. 1.Belt Driven Lathe 2.Motor Driven Lathe 3.Gear Head Lathe

  35. Bench Lathe • A bench top model usually of low power used to make precision machine small work pieces. • It is used for small w/p having a maximum swing of 250 mm at the face plate. Practically it consists of all the parts of engine lathe or speed lathe.

  36. Tool Room Lathe • A tool room lathe having features similar to an engine lathe is much more accurately built and has a wide range of spindle speeds ranging from a very low to a quite high speed up to 2500 rpm. • This lathe is mainly used for precision work on a tools, dies, gauges, and in machining work where accuracy is needed. • This lathe machine is costlier than an engine lathe of the same size.

  37. Automatic Lathe • A lathe in which the work piece is automatically fed and removed without use of an operator. It requires very less attention after the setup has been made and the machine loaded.

  38. Once tools are set and the machine is started it performs automatically all the operations to finish the job. • After the job is complete, the machine will continue to repeat the cycles producing identical parts. • An operator can maintain five or six such a types of lathes at a time simply look after the general maintenance of the machine and cutting tools.

  39. Turret Lathe • Turret lathe is the adaptation of the engine lathe where the tail stock is replaced by a turret slide(cylindrical or hexagonal). Tool post of the engine lathe is replaced by a square cross slide which can hold four tools.

  40. It has heavier construction and provides wider range of speeds. • The saddle carrying the turret head moves along the whole length of the bed. Much longer jobs can be machined. • Turret head directly mounted on the saddle. The front tool post can carry 4 tools and rear tool post may have 1 or 2 tools. Turret may have4 to 6 tools. • More than one tool may be set to operate simultaneously. There is no lead screw.

  41. Computer Controlled Lathe • A highly automated lathe, where both cutting, loading, tool changing, and part unloading are automatically controlled by computer coding. e.g. CNC Lathe M/C.(Computer Numerical Control Machine)

  42. VARIOUS PARTS OF THE LATHE

  43. Lathe Bed • This is heavy rugged casting made to support the working parts of lathe and also guide and align major parts of lathe. • Made to support working parts of lathe. • On top section are machined ways. • Guide and align major parts of lathe.

  44. Headstock • Clamped on left-hand end of bed • Headstock spindle:- • Hollow cylindrical shaft supported by bearings • Provides drive through gears to work-holding devices • Live center, faceplate, or chuck fitted to spindle nose to hold and drive work • Driven by stepped pulley or transmission gears • Feed reverse lever • Reverses rotation of feed rod and lead screw

  45. Quick Change Gear Box • Contains number of different-size gears • Provides feed rod and lead-screw with various speeds for turning and thread-cutting operations • Feed rod advances carriage when automatic feed lever engaged • Lead screw advances the carriage for thread-cutting operations when split-nut lever engaged Top View of gear box

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