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Quality Control QUALITY ASSURANCE (QA) 1. The operational techniques and activities that sustain the product or service quality to specified requirements.

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Presentation on theme: "Quality Control QUALITY ASSURANCE (QA) 1. The operational techniques and activities that sustain the product or service quality to specified requirements."— Presentation transcript:

1

2 Quality Control

3 QUALITY ASSURANCE (QA) 1. The operational techniques and activities that sustain the product or service quality to specified requirements. 1. The operational techniques and activities that sustain the product or service quality to specified requirements. 2. The use of such techniques and activities. 2. The use of such techniques and activities..

4 QUALITY ASSURANCE (QA) 3. Operations intended for the assessment of the quality of products at any stage of processing or distribution. 3. Operations intended for the assessment of the quality of products at any stage of processing or distribution. 4. Part of quality assurance intended to verify that components and systems correspond to predetermined requirements. 4. Part of quality assurance intended to verify that components and systems correspond to predetermined requirements.

5 QUALITY CONTROL (QC) Quality control, focuses on the end result, such as testing a sample of items from a batch after production. Quality control, focuses on the end result, such as testing a sample of items from a batch after production. Inspection takes place at all stages of the process from design to dispatch Inspection takes place at all stages of the process from design to dispatch

6 QUALITY CONTROL (QC) Basically quality control tests that the standards laid out by the quality assurance standards have been met Basically quality control tests that the standards laid out by the quality assurance standards have been met

7 QUALITY INSPECTION Inspection takes place at stages Inspection takes place at stages Goods inward Goods inward During production During production Final inspection Final inspection

8 QUALITY ASSURANCE VS. QUALITY CONTROL Quality Assurance An overall management plan to guarantee the integrity of data (The “system”) Quality Control A series of analytical measurements used to assess the quality of the analytical data (The “tools”)

9 TRUE VALUE VS. MEASURED VALUE True Value The known, accepted value of a quantifiable property Measured Value The result of an individual’s measurement of a quantifiable property

10 REPRODUCABILITY The ability of a system to achieve the same results when using different operators and different measuring equipment

11 ACCURACY VS. PRECISION Accuracy How well a measurement agrees with an accepted value Precision How well a series of measurements agree with each other

12 ACCURACY VS. PRECISION

13 ISO 9000 ISO 9000 Is an international standard that many companies use to ensure that their quality assurance system is in place and effective. Conformance to ISO 9000 is said to guarantee that a company delivers quality products and services. Is an international standard that many companies use to ensure that their quality assurance system is in place and effective. Conformance to ISO 9000 is said to guarantee that a company delivers quality products and services.

14 ISO 9001 ISO 9001 is for all organisations large or small and covers all sectors, including charities and the voluntary sector. It will help you to be more structured and organised. it is a process standard, not a service or product standard. ISO 9001 is for all organisations large or small and covers all sectors, including charities and the voluntary sector. It will help you to be more structured and organised. it is a process standard, not a service or product standard.

15 ISO 9001 ISO 9001 gives the requirements for what the organisation must do to manage processes affecting quality of its products and services. It does this through the creation of a Quality Management System. ISO 9001 gives the requirements for what the organisation must do to manage processes affecting quality of its products and services. It does this through the creation of a Quality Management System.

16 ISO 9001 The standard requires you to have certain documented procedures. They must meet the requirements as described in the following 6 clauses as mentioned in the standard: The standard requires you to have certain documented procedures. They must meet the requirements as described in the following 6 clauses as mentioned in the standard:

17 ISO 9001 ( clause 4.2.3) Control of documents ( clause 4.2.3) Control of documents (clause 4.2.4) Control of records (clause 4.2.4) Control of records (clause 8.2.2) Internal audit (clause 8.2.2) Internal audit (clause 8.3) Control of nonconforming product (clause 8.3) Control of nonconforming product (clause 8.5.2) Corrective action (clause 8.5.2) Corrective action (clause 8.5.3) Preventative action (clause 8.5.3) Preventative action

18 BENEFITS OF ISO 9001

19 Improved consistency of service and product performance Improved consistency of service and product performance Higher customer satisfaction levels. Higher customer satisfaction levels. Improved customer perception Improved customer perception Improved productivity and efficiency Improved productivity and efficiency

20 Cost reductions Cost reductions Improved communications, morale and job satisfaction Improved communications, morale and job satisfaction Competitive advantage and increased marketing and sales Competitive advantage and increased marketing and sales opportunities. opportunities. BENEFITS of ISO 9001

21 STANDARD FOR QUALITY MANAGEMENT SYSTEMS Products should conform to standards of quality assurance and demonstrate conformity to product requirements. Action should be taken to eliminate non conformity. Action should be taken prevent the use of non conforming products. (without waiting for the customer to complain) Products should conform to standards of quality assurance and demonstrate conformity to product requirements. Action should be taken to eliminate non conformity. Action should be taken prevent the use of non conforming products. (without waiting for the customer to complain)

22 MEASURING INSTRUMENTS Micrometers Micrometers Vernier Calipers Vernier Calipers Dial Indicators Dial Indicators Telescopic Gauges Telescopic Gauges Small Hole Gauges Small Hole Gauges Thickness Gauges Thickness Gauges Straight Edge Straight Edge

23 MICROMETERS

24 OUTSIDE MICROMETER Instrument for making precise linear measurements of dimensions such as diameters, thicknesses, and lengths of solid bodies. It consists of a C-shaped frame with a movable jaw operated by a screw. The accuracy of the measurements depends on the accuracy of the screw-nut combination.

25 IMPERIAL AND METRIC

26 INSIDE MICROMETER

27 DEPTH MICROMETER

28 DIGITAL MICROMETERS

29 COMBINATION DIGITAL Metric or Imperial at the push of a button

30 PARTS OF A MICROMETER

31 READING THE SLEEVE AND THIMBLE Imperial Micrometer 31 2 Number on Sleeve Graduation on Sleeve Number on Thimble Thimble numbers go from 0 to 20

32 SAMPLE READING First number is the size of the Mic Example using a 0-1” Outside Micrometer Second number is the first number on Sleeve.000 Third number is.025 graduations you see on Sleeve.025 x 2 =.050 Fourth number is read on the Thimble.016

33 RECORDING MEASUREMENT FROM SAMPLE READING  First reading – Range of Mic. 0 – 1” so the first number would be  Second reading – number on Sleeve Number you see is Zero so it would be.000  Third reading – graduation on Sleeve Two graduations exposed so number is.050  Final number is number on the Thimble Final number is.016

34 TOTAL READINGS  First reading – Range of Mic  Second reading – number on Sleeve  Third reading – graduation on Sleeve  Final number is number on the Thimble ______ Total is ? 0.066

35 Reading an Imperial Micrometer

36 READING AN IMPERIAL MICROMETER EXERCISE 1 (2-3” MIC) Answer : 2.550

37 READING AN IMPERIAL MICROMETER EXERCISE 2 (0-1” MIC) Answer: 0.802

38 READING AN IMPERIAL MICROMETER EXERCISE 3 (1-2” MIC) Answer: 1.645

39 CALIPERS

40 INTRODUCTION Calipers can be direct reading or measuring transferring tools. Calipers can be direct reading or measuring transferring tools. Direct reading calipers are capable of a wider measurement range than micrometer calipers. Direct reading calipers are capable of a wider measurement range than micrometer calipers. Six (6), eighteen (18) and twenty four (24) inch are popular. Six (6), eighteen (18) and twenty four (24) inch are popular.

41 INTRODUCTION Three common designs of direct reading calipers; Three common designs of direct reading calipers; Vernier Vernier Dial Dial Digital Digital

42 VERNIER CALIPER Vernier calipers are an old tool that has been mostly replaced by dial and digital calipers. Vernier calipers are an old tool that has been mostly replaced by dial and digital calipers. They are manufactured with decimal scales, metric scales and fractional scales. They are manufactured with decimal scales, metric scales and fractional scales. The Vernier scale is still used on many mechanical measuring tools. The Vernier scale is still used on many mechanical measuring tools.

43 VERNIER SCALE The reference point is the 0 on the vernier scale. The reference point is the 0 on the vernier scale. To read a Vernier, the line of coincidence must be located. To read a Vernier, the line of coincidence must be located. The line of coincidence (LOC) is the line on the Vernier that coincides with a line on the main scale. The line of coincidence (LOC) is the line on the Vernier that coincides with a line on the main scale. Illustration LOC = 19 Illustration LOC = 19 In theory only one LOC is possible, but usually when reading the vernier it appears several exist. When this occurs pick the middle line. In theory only one LOC is possible, but usually when reading the vernier it appears several exist. When this occurs pick the middle line. A Vernier is a mechanical means of magnifying the last segment on the main scale so addition subdivisions can be made.

44 VERNIER CALIPER- PRACTICE Smallest whole unit1.000 Tenths of an inch0.200 Twenty five thousands0.000 Vernier scale0.011 Sum (measurement)1.211 LOC Read the Vernier caliper in the illustration.

45 DIAL CALIPER A dial replaces the Vernier. This makes the caliper easier to read. The reader must still determine the units and graduations.

46 READING A VERNIER CALIPER #

47 READING A VERNIER CALIPER #

48 READING A VERNIER CALIPER #

49 MEASUREMENT TRANSFERRING TOOLS

50 INTRODUCTION Measurement transferring tools are tools that collect a measurement, but do not have a scale to read the measurement. Measurement transferring tools are tools that collect a measurement, but do not have a scale to read the measurement.

51 INTRODUCTION. Common tools are: Common tools are: Spring calipers Spring calipers Dividers Dividers Telescoping gauges Telescoping gauges Ball gauges Ball gauges

52 SPRING CALIPERS Spring calipers are used to transfer measurements. Spring calipers are used to transfer measurements. Three types of spring calipers Three types of spring calipers Outside Outside Inside Inside Hermaphrodite Hermaphrodite

53 DIVIDERS Dividers are very useful for laying out several equal distances or transferring a distance measurement when other measuring devices cannot be used. Dividers are very useful for laying out several equal distances or transferring a distance measurement when other measuring devices cannot be used.

54 TELESCOPING GAGES Telescoping gages are used to measure inside diameters. Telescoping gages are used to measure inside diameters. One or both ends are spring loaded so they can be retracted and inserted into the hole being measured. One or both ends are spring loaded so they can be retracted and inserted into the hole being measured. The measurement is made with a caliper or micrometer. The measurement is made with a caliper or micrometer.

55 BALL GAUGES Ball gauges are use to transfer measurements that are too small for telescoping gauges. Ball gauges are use to transfer measurements that are too small for telescoping gauges. The ball is split and a tapered wedge is used to increase and decrease the diameter of the ball halves. The ball is split and a tapered wedge is used to increase and decrease the diameter of the ball halves.

56 MEASURING STRAIGHTNESS Measuring straightness manually with (a) a knife-edge rule and (b) a dial indicator.

57 MEASURING FLATNESS (a)Interferometry method for measuring flatness using an optical flat. (b) Fringes on a flat, inclined surface. An optical flat resting on a perfectly flat workpiece surface will not split the light beam, and no fringes will be present.

58 (c) Fringes on a surface with two inclinations. Note: the greater the incline, the closer together are the fringes. (d) Curved fringe patterns indicate curvatures on the workpiece surface.

59 MEASURING ROUNDNESS (a) Schematic illustration of out-of-roundess (exaggerated). Measuring roundess using (b) a V-block and dial indicator, (c) a round part supported on centers and rotated, and (d) circular tracing.

60 MEASURING GEAR-TOOTH THICKNESS AND PROFILE Figure 35.8 Measuring gear-tooth thickness and profile with (a) a gear-tooth caliper and (b) pins or balls and a micrometer.

61 OPTICAL CONTOUR PROJECTOR A bench-model horizontal-beam contour projector with a 16-in. diameter screen with 150-W tungsten halogen illumination.

62 FIXED GAUGES Figure (a) Plug gage for holes with GO and NOT GO on opposite ends. (b) Plug gage with GO and NOT GO on one end. (c) Plain ring gages for gaging round rods. Note the difference in knurled surfaces to identify the two gages. (d) Snap gage with adjustable anvils.

63 Manufacturing, Engineering & Technology, Fifth Edition, by Serope Kalpakjian and Steven R. Schmid. ISBN © 2006 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. ELECTRONIC GAGE Figure An electronic gage for measuring bore diameter. The measuring head is equipped with three carbide-tipped steel pins for wear resistance. The LED display reads mm. Source: Courtesy of TESA SA.

64 ELECTRONIC GAGE MEASURING VERTICAL LENGTH Figure An electronic vertical-length measuring instrument with a resolution of 1 μm

65 LASER MICROMETERS Figure (a) and (b) Two types of measurements made with a laser scan micrometer. (c) Two types of laser micrometers. Note that the instrument in the front scans the part (placed in the opening) in one dimension; the larger instrument scans the part in two dimensions.

66 COORDINATE- MEASURING MACHINE (a) Schematic illustration of a coordinate-measuring machine. (b) A touch signal probe. (c) Examples of laser probes. (d) A coordinate-measuring machine with a complex part being measured. (b)(c)(d)

67 COORDINATE-MEASURING MACHINE FOR CAR BODIES Figure A large coordinate- measuring machine with two heads measuring various dimensions on a car body.

68 TOLERANCE CONTROL Tolerance is the range of sizes in within which a component is acceptable

69 METHODS OF ASSIGNING TOLERANCES Various methods of assigning dimensions and tolerances on a shaft: (a) bilateral tolerance, (b) unilateral tolerance, and (c) limit

70 GO AND NO GO GAUGES

71 GAUGES

72 SIMPLE PLATE GAUGE Flatness Gauge

73 FEELER GAUGES

74 SNAP GAUGE

75 EXTERNAL THREAD GAUGE

76 RING THREAD GAUGE

77 PLUG GAUGES

78 THREAD PLUG GAUGE

79 THREAD PROFILE GAUGE

80 'GO' LIMIT 'go' limit is the one between the two size limits which corresponds to the maximum material limit 'go' limit is the one between the two size limits which corresponds to the maximum material limit the upper limit of a shaft and the lower limit of a hole the upper limit of a shaft and the lower limit of a hole 'GO' gauge can check one feature of the component in one pass 'GO' gauge can check one feature of the component in one pass

81 'NO GO' LIMIT 'no go' limit is the one between the two size limits which corresponds to the minimum material condition 'no go' limit is the one between the two size limits which corresponds to the minimum material condition the lower limit of a shaft and the upper limit of a hole. the lower limit of a shaft and the upper limit of a hole.

82 5.2.1 LIMIT PLUG GAUGE Limit plug gauges are fixed gauges usually made to check the accuracy of a hole with the highly finished ends of different diameters Limit plug gauges are fixed gauges usually made to check the accuracy of a hole with the highly finished ends of different diameters If the hole size is correct within the tolerable limits, the small end (marked “go”) will enter the hole, while the large end (“not go”) will not. If the hole size is correct within the tolerable limits, the small end (marked “go”) will enter the hole, while the large end (“not go”) will not.

83 PLUG GAUGE EXAMPLE Dimension on part to gauge Dimension on part to gauge The nominal hole size on part to gauge is ”; The nominal hole size on part to gauge is ”; Tolerance of the hole is ”/-0.000” ; Tolerance of the hole is ”/-0.000” ; This means the hole must be manufactured somewhere between ” and ” in size; This means the hole must be manufactured somewhere between ” and ” in size;

84

85 5.2.2 LIMIT RING GAUGE Limit plug gauges are fixed gauges usually made to check the accuracy of a shaft with highly finished ends of different diameters is used Limit plug gauges are fixed gauges usually made to check the accuracy of a shaft with highly finished ends of different diameters is used If the shaft size is correct within the tolerable limits, the large end (marked “go”) will go through the shaft, while the small end (“not go”) will not. If the shaft size is correct within the tolerable limits, the large end (marked “go”) will go through the shaft, while the small end (“not go”) will not.

86

87 RING GAUGE EXAMPLE Dimension on part to gauge: Dimension on part to gauge: Post on part to gauge is ”; Post on part to gauge is ”; Tolerance of post on part is ”/-0.000”; Tolerance of post on part is ”/-0.000”; This means the post will be somewhere between ” and ” in size; This means the post will be somewhere between ” and ” in size;

88 STANDARD DEVIATION Find the mean and the standard deviation for the values 78.2, 90.5, 98.1, 93.7, The mean is 91, and the standard deviation is about = 6.8 = = 91 Find the mean. ( ) 5 x  = Find the standard deviation.  (x – x) 2 n Organize the next steps in a table – – x x x – x (x – x) 2

89 One standard deviation away from the mean (μ) in either direction on the horizontal axis accounts for around 68 percent of the data. Two standard deviations away from the mean accounts for roughly 95 percent of the data with three standard deviations representing about 99.7 percent of the data.

90

91 SIX SIGMA one to six sigma conversion table 'Long Term Yield' (basically the percentage of successful outputs or operations) Defects Per Million Opportunitie s (DPMO) 'Processs Sigma' % , , , ,4621

92 A six sigma process is one in which % of the products manufactured are statistically expected to be free of defects (3.4 defects per million), A six sigma process is one in which % of the products manufactured are statistically expected to be free of defects (3.4 defects per million),

93 SIX SIGMA Six Sigma team leaders (Black Belts) work with their teams (team members will normally be people trained up to 'Green Belt' accreditation) to analyse and measure the performance of the identified critical processes. Measurement is typically focused on highly technical interpretations of percentage Six Sigma team leaders (Black Belts) work with their teams (team members will normally be people trained up to 'Green Belt' accreditation) to analyse and measure the performance of the identified critical processes. Measurement is typically focused on highly technical interpretations of percentage

94 DOCUMENT CONTROL There must be evidence of the existence of a system There must be evidence of the existence of a system A record of the correct operation must be kept A record of the correct operation must be kept This is important to trace evidence of inspection in case of future complaints or problems This is important to trace evidence of inspection in case of future complaints or problems

95 MTBF Mean time between failures (MTBF) is the predicted elapsed time between inherent failures of a system during operation Mean time between failures (MTBF) is the predicted elapsed time between inherent failures of a system during operation MTBF can be calculated as the (average) time between failures of a system MTBF can be calculated as the (average) time between failures of a system


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