Download - Cleaning of Surfaces
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