Cleaning of Surfaces

• 3 types – Mechanical Cleaning

• Physically disturb contaminants

– Electrolytic Cleaning • Abrasive bubbles aid in

contaminant removal

– Chemical Cleaning • Solution • Saponification • Emulsification • Dispersion • Aggregation

Engineering Metrology and Instrumentation

Metrology refers to the measurement of any type of dimensions

(length, thickness, diameter, angle, etc.)

Focus on Dimensional Tolerance (functionality, interchangeability, cost)

Describing Quality of Instruments

• Resolution- the smallest difference in

dimensions that an instrument can detect.

• Precision- the instruments ability to give

repeated measurements (thermal

expansion affects precision, standard

measuring temperature is 200 C).

• Accuracy- The ability of a measurement

to match the actual value of the quantity

being measured.

Types of Measurement and Instruments Used

Types of Measurement and Instruments Used

Common Analog Instruments

A caliper gage with a vernier

A vernier

The Micrometer

(a) (c)

Analog Micrometer Digital Micrometer

Angle-Measuring Instruments

Bevel Protractor

Vernier for angular measurement

Angle-Measuring Instruments Sine Bar

Gage blocks are added until the top surface is parallel to the

surface plate. The angle is calculated using trig. relationships.

Comparative Length Measurement

Multiple-Dimension

Gaging

Electronic Gages

Measuring Bore

Diameters Vertical Length

Mesauring Instrument

Laser Scan Micrometer

Straightness Measurement

Interferometry for Measuring Flatness

Optical Flat is a glass disk or fused-quartz disk with

parallel flat surfaces. A light beam with one wavelength is

aimed at the surface at an angle and splits into two beams.

The number of fringes relates the distance between part

and flat.

Interferometry for Measuring Shaped or Textured Surfaces

Fringes on a surface

with two inclinations,

the greater the incline,

the closer the fringes.

Curved fringe

patterns indicate

curvatures on the

workpiece surface

Fringe pattern

indicating a scratch on

the surface.

Measuring Roundness

Measuring roundness using

V-block and dial indicator

Measuring Roundness

Part supported

on centers and

rotated

Circular tracing, with part being

rotated on a vertical axis

Measuring Profiles

Radius Gages Dial Indicators

Measuring Profiles

Gear-Tooth Caliper Gear-Tooth Micrometer

Horizontal-Beam Contour Projector

Image is

projected on

screen at

magnification of

100X or higher.

Measurements

made directly

on screen.

Gages

Plug gages

for holes

Ring gages for

round rods

GO means smaller than desired size and should fit perfectly, if NOT GO gage also fits then tolerance is not met.

Gages

Snap Gage with

adjustable anvils

Gages

Pneumatic Gage

Modern Measuring Instruments and Machines Electronic gauges Laser Micrometers Laser Interferometry

Photoelectric digital length measurement Coordinate-measuring machines (CMM)

Electronic Gauges

• Determine travel length by changes in electrical resistance, inductance, or capacitance.

• A commonly used E-Gauge is the linear-variable differential transformer (LVDT)

• Generally use a very accurate specified probe tip.

Laser Micrometers

• A laser beam scans a workpiece, generally at a rate of 350 times per second.

• Generally capable of resolutionsas high as 0.125 µm (5 µin).

Laser Interferometry

• Used primarily to check and calibrate machine tools.

• Also are used to compensate for positioning errors in CMM and CNC machines

Photoelectric Digital Length Measurement

• Measures basic dimensions of general 3D parts.

• Resolution ranges from 5 - 0.01 µm.

Coordinate-Measuring Machines (CMM)

• Very versatile and capable of measuring complex profiles with resolution of 0.25 µm; 10µin at high speeds.

• Larger machines can be expensive although most of the touch probe machines for small shops cost around $20k

More CMM’s

References

• www.brownandsharpe.com

• www.faro.com

• www.lk-cmm.com

• www.renishaw.com

• http://www.nd.edu/~manufact/index3.htm

• http://www.nd.edu/~manufact/figures.html