MEM560MEM560Manufacturing ProcessesManufacturing ProcessesTopic 2Topic 2

Rahani Abdul RahmanCo-ordinator: PM Yusof MohdFKM

Topic 2Topic 2

2.0 Introduction2.1 Tolerance, Limits and Fit2.2 Linear Measurement Using Tools and such

as Digital Gauges, Micrometer and Calipers2.3 Angular Measurement Using Profile

Projector2.4 Straightness, Flatness, and Roundness

Measurement2.5 Surface Roughness Measurement2.6 Measurement Using GO and NO GO

ConceptTopic 2 2

Introduction to Metrology Introduction to Metrology and Instrumentation and Instrumentation Science of measurement –

experimental and theoretical with certain level of uncertainties.

i.e: Length – Mass – Flatness – Profiles – taper

Why is it important?

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With a universal meaningWith a defined

uncertaintiesWith a judicious standardizationWith/using good and correct

technique

Tolerance, Limits and FitTolerance, Limits and Fit

2.1 Introduction2.2 Linear Measurement Using Tools and

such as Digital Gauges, Micrometer and Calipers

2.3 Angular Measurement Using Profile Projector

2.4 Straightness, Flatness, and Roundness Measurement

2.5 Surface Roughness Measurement2.6 Measurement Using GO and NO GO

ConceptTopic 2 4

StandardsStandardsWho are the respective parties

responsible to maintain standards of a universally agreed set of guidelines for interoperability.

Local : SIRIMInternational : ISODoing an inspection? With/without Doing a measurement? – With

equipment/ apparatus (attributes – Yes/No OR variables – dimensional wise)

Differentiate the Metric (SI) and Imperial System measurement.

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Category Name Abbv

Length Metre m

Mass kilogram Kg

Time Second S

Electric current

Ampere A

Temperature

Kelvin K

Amount of substance

Mole Mol

Luminous intensity

Candela cd

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Derivations;

-Farad (F)-Hertz (Hz)-Joule (J)-Newton (N)-Ohm (Ω)-Pascal (Pa)-Volt (V)-Watt (w)

Accurate

Allowances

Tolerances

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4.25 +0.01 / - 0.01(BILATERAL)

4.25 +0.01 / -0.00(UNILATERAL)

4.2495 / 4.2505 LIMIT DIMENSIONS

Clearance fit & loose fit / free fit Interference fit

Errors With all dimension inspected, tendency for errors are

great with 3 major categories namely;1. Systematic error- Due to quality of equipment: causes consistent signs

(+ve or –ve)- Due to ambient conditions : temperature, humidity, CO2

or pressure of work piece or instrument2. Accidental error- Due to the smallest gradient in equipment or - Inexperience of equipment user3. Illegitimate error

Calibration- Equipment is compared to;1. primary standard2. Secondary standard (with higher accuracy than the

equipment itself)3. Known input source

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2.2 Linear Measurement Using Tools 2.2 Linear Measurement Using Tools and such as Digital Gauges, and such as Digital Gauges, Micrometer and CalipersMicrometer and Calipers

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Digital Caliper Dial Caliper Vernier Caliper

Point Micrometer

Dual Point Micrometer

Outside Micrometer

Jaw

Nibs

Anvil

Spindle

Frame

Thimble

Sleeve

Ratchet stop

2.3 Angular Measurement Using 2.3 Angular Measurement Using Profile ProjectorProfile Projector

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Main criteria for a PP/optical comparison ;-Diascopic (behind) / episcopic (above) illumination-Measuring stroke-Contour illumination system-Standard equipped turret-X and Y wheel-Digital displays-Focusing (motor-driven or manual)-Bulbs-Overlay Charts-Resolutions-Data processing unit

Angle measurement;Protractor : measuring angle via displacement method in reading of degrees

2.4 Straightness, Flatness, and 2.4 Straightness, Flatness, and Roundness MeasurementRoundness Measurement

Straightnessi.e Laser beamFlatnessi.e reference of surface (3 points)

onto new reference plane (3 points)i.e use of calibrated granite tableRoundnessi.e use of dial indicator with object

set on V-block, error in roundness can be directly known by comparing the peak height as measured by the dial gauge.

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2.5 Surface Roughness 2.5 Surface Roughness MeasurementMeasurement

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Characteristic of a surface is its structure, texture and roughness.-Structured : microscopic level - effect of processes that the raw material had gone through.-Texture : repetitive and/or random deviations from the nominal surface of an object (roughness, waviness, form, lays and flaws).surface profile = error of form + waviness + roughness-Roughness : surface profile (peaks and valley)-Integrity : sub-surface alterations produced due to manufacturing.

2.6 Measurement Using GO and 2.6 Measurement Using GO and NO GO ConceptNO GO ConceptGauges : device that measures the dimension of an

object or to measure the dimension of produced part if it is within specified limits.

: gauge of a numeric scale for metal thickness

GO-NO-GO and GO gaugesGauges that gives categorical data on one or

more dimension of a work piece is within specification.

Limit Gauges / Attribute gauges

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