1. Introduction to Machining
Module 1
Introduction to Machining

2. Module objectives
Recognize the function and importance of machine tools.
Differentiate between the basic categories of machine tools.
Read and understand the main technical drawings’ symbols.
Take precise measurement using Vernier Caliper and Micrometer.

3. The importance of tools
machine tools are used directly in the manufacture of products
machine tools are required to produce the machinery and the equipment necessary for product processing

4. What is a Machine Tool?
A machine tool is a power-driven machine not portable by hand, used to shape or form metals or materials by cutting, impacting, forming, eroding, or a combination of these processes.
CNC milling is a machine tool

5. The main categories of machine tools:
Non-chip producing machine tools.
Conventional chip producing machine tools.
New Generation of machine tools

6. Non-chip producing machine tools
This type of machines shapes metals by shearing, pressing, and drawing to a desired shape.
Non-chip producing machine tool

7. Conventional chip producing machine tools
They shape metal to a size and contour by cutting away the unwanted portions in the form of metal chips
The collection of material-working processes used is called conventional machining.
Process of Chip removal

8. Conventional chip producing machine tools
The operator uses machine handwheels to manually control the machine to produce the part
The accuracy of the part produced depends upon the skills of the operator or machinist.
Hand wheels of conventional machine tool

9. Examples of chip producing machine tools
Conventional lathe machine
Conventional milling machine

10. New Generation of machine tools
Computerized Numerical Control (CNC) machines
Electric Discharge Machines (EDM)
Electrochemical Machines
Their purpose:
To increase the production rate
To increase the preciseness of machined parts
The programmer programs the machine control unit (MCU), through the use of symbols, letters, and numbers (coded instructions) which automatically control the machine tool movements to produce the desired part

11. New Generation of machine tools
CNC lathe machine
CNC milling machine
Computerized Numerical Control machine tool

12. Skills required to use Conventional machine tools
Drafting,
Read drawings and
Taking precise measurements.

13. Engineering drawing
It is a common language between drafts persons, tool designers, engineers machinist and toolmakers.
Drawings are made up of a variety of lines, which represent surfaces, edges, and contours of a workpiece.
By adding symbols, dimension lines, sizes, and word notes, the draftsperson can indicate the exact specifications of each individual part

14. Example of engineering drawings

15. Orthographic Projection
Is a way of drawing a 3D object from different directions
They are useful especially when a design is almost ready to manufacture
Three standard views in orthographic drawings

16. Sectional Views
They are used to clarify interior or hidden details on a multi-view drawing of an object.
They are located by creating a Cutting Plane Line in one view.
"Section Lining" or "Hatching" is added to the Section view mainly to distinguish the solid portions from the hollow areas of an object.
Sectional Views

17. Isometric drawings
They consist of two-dimensional drawings that are tilted at some angle to expose other views and give the viewer the feeling that what he or she is viewing is a three-dimensional drawing.
Isometric drawing

18. Tolerance It is the permissible variation of specified size of a part
The basic dimensions plus or minus the variation allowed is given on a drawing
Example:
The largest permissible dimension = 70.1 mm
( = 70.1 mm)
The smallest permissible dimension = 69.7 mm
(70 – 0.3 = 69.7 mm)
The tolerance = 0.4 mm (70.1 – 69.7 = 0.4 mm)

19. Allowance
It is the intentional difference in the sizes of mating parts
On a shop drawing, both the shaft and the hole would be indicated with maximum and minimum sizes to produce the best fit.

20. Fit Fit is the range of tightness between two mating parts.
There are two general classes of fits:
Clearance fits, whereby a part may revolve or move in relation to a mating part.
Interference fits, whereby two parts are forced together to act as a single piece

21. Common Symbols and abbreviations
R: Radius of a circle. Fig. 1
Ø: Dia. = Diameter. Fig. 2
TYP: Typical dimensions. Fig. 2
P: Pitch of the thread Fig. 3
mm: the unit of measurement is millimeter
M: Metric Thread
Fig. 1
Fig. 3
Fig. 2

22. M: Metric Thread Example: M10 X 1.5: M = metric thread (Screw)
10 = diameter
1.5 = Thread pitch

23. Measurement There are two measuring systems:
International system of measurements (SI)
(SI from System International)
Imperial system (Old system using Yard as basic unit of length)
1 yard = 36 inch
I inch = 25.4 mm

24. Using Measuring Tools Care must be taken when using measuring tools.
Most of tools have very sharp edges that may result in severe injuries.
Tools could be damaged easily if bended, twisted or screwed with extra force.
When using the graduated measuring tools, you must look at 90 degrees for accurate measurement.

25. Steel Rule
Metric steel rules, are usually graduated in millimeters and half-millimeters,
They are used for making linear metric measurements that do not require great accuracy.

26. Metric Vernier There are three basic types of Vernier caliper.
Standard Vernier
Dial Vernier
Digital Vernier

27. Metric Vernier
The Vernier caliper is used to measure outside, inside and depth measurement
The accuracy of a measurement system is the degree of closeness of measurements of a quantity to that quantity's actual (true) value.
Outside Measurements
Inside Measurements
Depth Measurements

28. Vernier Measurements

29. Metric Vernier
The Vernier caliper with 10 divisions in Vernier scale (Vernier scale is the bottom scale on the Vernier) is accurate to (1/10) ±0.1 mm.
reading = 15.8 mm

30. Metric Vernier
The Vernier caliper with 20 divisions in Vernier scale is accurate to (1/20) ±0.05 mm. Fig (b) .

31. Metric Vernier
The Vernier caliper with 50 divisions in Vernier scale is accurate to (1/50) ±0.02 mm. Fig (c).

32. Metric Micrometer
It is a device incorporating a calibrated screw used widely for precise measurement of small distances in mechanical engineering and machining as well as most mechanical trades.

33. Basic types of micrometers
Outside micrometer.
For external measurement.
Inside micrometer,
used to measure the diameters of holes.
Depth micrometer
measures depths of slots and steps.

34. Reading the micrometer
Each division on the upper scale on the sleeve equal 1 mm.
Each line appears after the upper scale reading is equal to 0.5 mm.
The micrometer screw gauge also uses an auxiliary scale (measuring hundredths of a millimeter) which is marked on a rotary thimble.
The micrometers in our laboratory have a pitch of 0.50 mm

35. Example 1
_______ 5.78 mm

36. Example 2
5.00 +
0.28
_____
5.28 mm

37. Digital micrometers
Digital micrometers are also available to give direct reading.

38. Prepare the blank part
Power hacksaw is used to cut the blank part from a long bar.
Cutting fluids must be used when cutting hard materials (steel).

39. End Of Module ONE

40. Safety in the Machine shop
Module Two
Safety in the Machine shop

41. Module Objectives Recognize safe and unsafe work practices in a shop.
Identify and correct hazards in the shop area.
Perform his job in a manner that is safe for him and others in the machine shop.

42. Safety is everyone’s business and responsibility

43. Safety It is everyone’s business and responsibility
Accidents don’t just happen; they are caused.
The machinist must first develop safe work habits

44. Safe Work Habits A safe worker should:
Be neat, tidy, and safely dressed for the job.
Develop responsibility for personal safety and the safety of fellow workers.
Think safely and work safely at all times.

45. Categories of safety in a machine shop
Practices that will prevent injury to workers.
practices that will prevent damage to machines and tools.

46. Personal Grooming (Preparations)
Always wear approved safety glasses in any area of the machine shop.
The most common are plain safety glasses with side shields. The lenses are made of shatterproof glass.
Plastic safety goggles. They are generally worn by anyone wearing prescription eyeglasses.

47. Personal Grooming (Preparations)
2. Never wear loose clothing when operating any machine:
Always roll up your sleeves or wear short sleeves.
Clothing should be made of hard, smooth material that will not catch easily in a machine.
Remove your necktie before starting a machine.

48. Personal Grooming (Preparations)
2. Never wear loose clothing when operating any machine:
When wearing a shop apron, always tie it at the back and never in front of you

49. Personal Grooming (Preparations)
3. Never wear gloves when operating a machine. 4. Wear safety shoes 5. Long hair must be protected 6. Remove wrist watches and rings

50. Housekeeping The following points should be observed.
Always stop the machine before you attempt to clean it. 
Always keep the machine and hand tools clean and tidy.
Always use a brush, not a piece of cloth to remove any metal chips.

51. Housekeeping Oily surfaces can be dangerous.
Never place tools or materials on the floor close to a machine.
Sweep up the metal chips on the floor frequently.
Do not place tools and materials on the machine table; use a bench near the machine

52. Housekeeping
Never use compressed air to remove chips from a machine. Not only it is a dangerous practice because of flying metal chips, but small chips and dirt can become wedged between machine parts and cause undue wear.
Return bar stock to the storage rack after cutting off the required length.

53. Safe Work Practices
Do not operate any machine before understanding its mechanism and knowing how to stop it quickly.
Before operating any machine, be sure that the safety devices are in place and in working order.

54. Safe Work Practices
Always disconnect the power when making repairs to any machine.
Always be sure that the cutting tool and the workpiece are properly mounted before starting the machine
5. Never use a rag near the moving parts of a machine.

55. Safe Work Practices Keep hands away from moving parts.
Never measure, clean, or make any adjustment unless the machine is stopped.
Never have more than one person operate a machine at the same time.

56. Safe Work Practices
Never start a machine until you are sure that the cutting tool and machine parts will clear the workpiece.
Before you handle any workpiece, remove all burrs and sharp edges with a file.
Do not attempt to lift heavy or odd-shaped objects that are difficult to handle on your own.

57. Safe Work Practices For heavy objects, follow safe lifting practices:
Assume a position in which you keep your knees bent and back straight.
Grasp the object firmly.
Lift the object by straightening your legs and keeping your back straight.
Be sure the work is clamped securely in the vise or to a machine table.

58. Safe Work Practices
Get first aid immediately for any injury, no matter how small. Report to your instructor.
Use the proper wrench for the job, and replace nuts with worn corners.
It is safer to pull on a wrench than to push.

59. Fire Prevention Always dispose oily rags in proper metal containers.
Know the location and the operation of every fire extinguisher in the shop
Know the location of the nearest fire exit. 
Know the location of the nearest fire-alarm box and its operating procedure.

60. Electric hazards
Stick to the rules and procedures regarding the electric hazards and safety provided through out the electrical course.

61. Solve the worksheet in class.

62. Safety Contract I RECOGNIZE THAT:
Safety is my responsibility when using a tool.
Safety regulations have been provided to me.
The possibility of accident and injury increases if I do not follow all the safety guidelines.
I must act responsibly to ensure my own safety AND the safety of others in the work area. 
I AGREE TO:
Never work in the shop without my teacher supervision.
Read and practice all the safety regulations that have been handed over to me in this course or have been posted in the work areas.
Act in a responsible manner at all times in the workshop.
Follow all instructions given by the teacher.
Immediately report any unsafe condition or activity to my teacher.
Wear eye protection at all times when working with tools or working anywhere near someone who is using tools.
Cut or Tie back long hair, remove jewelry, secure loosed clothing, and wear safety shoes in the Workshop.
Clean all work areas and put equipment away before leaving the workshop. 
Student signature _____________________ Section__________
I, ________________________________________, have read and agree with all the safety instructions.
Date____________________________ Student ID_______

63. References
Technology of Machine Tools. Seventh Edition, McGraw-Hill Companies,
Machine tool and Manufacturing technology, Steve F. Krar, Mario Rapisarda, Albert F. Check., Delmar Publishers.
championmedicalservices.wordpress.com.