RSWA

1
RSWA

• Training Course
• Alex Denisov

2
Outline

• Overview
• Basic Theory
• RSWA Components
• RSWA Software

3
Overview

• Ultrasonic Testing
• Visual Inspection
• Pry Chisel Test
• Ultrasonic Spot Weld Inspection

4
Ultrasonic Testing

• Ultrasonic testing is intended to replace or
  reduce the pry chisel tests.
• Reduction of scrap
• Reduction in physical effort
• Reduction in possible injury
• Faster/easier checks of spot weld gun
  controller adjustments

5
Visual Inspection

• Still an important part of the inspection. Can
  identify an unacceptable or defective weld. The
  inspector should always visually examine the
  welds for
• Coloration of the weld area
• Excessive indentation
• Edge and radius welds
• Surface cracks and pits
• Deformed metal, misaligned electrodes
• Electrode deposits (brassing)
• If the weld can be rejected visually, there is no
  reason to do the ultrasonic check.

6
Pry Chisel Test

• Used as necessary along with the ultrasonic
  inspection. Whenever a no read situation is
  encountered with the ultrasonic method, the
  suspect weld must be pry tested. This may be
  occasionally necessary because of
• Burn through (a hole through the metal)
• Deep cavities/pits/pin holes

7
Ultrasonic Spot Weld Inspection

• Can be used to identify weld quality without
  destroying the part. The advantages of ultrasonic
  inspection over other inspection methods include
• Inspection of welds that are difficult to chisel
• Verification of stick welds
• Parts do not have to be destroyed
• Quick inspection of welds after servicing or
  repair procedures
• Lower production costs
• Less downtime
• Better indication of weld quality

8
Basic Theory

• Velocity, Frequency, Wavelength, and Amplitude
• Piezoelectric Effect
• Pulse-Echo Method
• Reflections Inside the Weld
• Mechanical and Electronic Scanning
• Matrix Transducer

9
Velocity Frequency

• Sound is a mechanical energy transmitted by
  pressure waves in a medium. Every sound wave is
  associated with cyclic motion of particles from
  which the medium is composed.
• Velocity of sound indicates how fast a sound wave
  travels through a material. The velocity depends
  on mechanical properties of the material
  (elasticity, density) and also on mode of
  vibration.
• Frequency of sound is a rate at which material
  particles oscillate when a sound wave propagates
  through it. Frequency is measured in oscillations
  per second, or hertz (Hz).
• Sound frequencies relative to the human hearing
  range are
• Subsonic below 20 Hz
• Sonic 20 Hz to 20 kHz (the range of human
  hearing)
• Ultrasonic greater than 20 kHz

10
Wavelength Amplitude

• Wavelength indicates how far a wave travels
  during one oscillation wavelengths are measured
  in meters or other length units.
• Amplitude characterizes the range of oscillation
  of particles inside the material when a wave
  passes through it. Waves with larger the
  amplitudes, transfer more energy.

11
Sound Velocities
Material Velocity, m/s Material Velocity, m/s
Aluminum 6,320 Silver 3,600
Copper 4,660 Steel, 1020 5,890
Gold 3,240 Steel, 4340 5,850
Iron 5,900 Steel, Stainless 302 5,660
Iron, cast 3,500 Tin 3,320
Lead 2,160 Titanium 6,100
Platinum 3,960 Tungsten 5,180
Polystyrene 2,340 Water (20ºC) 1,480
PVC, hard 2,395 Zinc 4,170
12
Piezoelectric Effect

• Certain piezo-ceramics and piezo-compozite
  materials generate mechanical energy when
  electrical energy is applied and vice versa. The
  frequency of the wave depends on material
  properties and the thickness of the material.
• The ultrasonic probe is also called transducer
  because it transforms electrical pulse into
  ultrasonic wave and back.

13
Pulse-Echo Method
14
Energy Distribution
15
Reflections in Welded Parts
16
Mechanical vs. Electronic Scanning
17
Mechanical vs. Electronic Scanning
Mechanical scanning Electronic scanning
High resolution images show tiniest details of the nugget structure Low resolution images
Slow scanning. It takes several seconds to obtain a single image. High scanning speed. At present stage of technology, the speeds of up to 3 frames per second can be achieved
Large size, most mechanical scanners are essentially desktop devices. A small probe with no moving parts allows designing hand-held devices
Fragile and expensive Robust design, much cheaper when systems with mechanical scanning
18
Matrix Transducer
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RSWA Components

• Matrix Transducer
• CPU
• DSP Board

20
Matrix Transducer

• ? Sensor
• ? Protective case
• ? Delay
• ? Coupler

21
Matrix Transducer

• Transducer specifications
• Frequency 15 MHz
• Number of Channels 52
• Elementary pitch 1.25 0.05 mm
• Inter-element spacing 0.1 0.05 mm
• Stainless housing
• 2 m cable made of 52 separate coaxial cables in a
  common ground shield, protective cover

22
CPU

• The CPU unit is a fully functional computer, a
  tablet PC, which runs Windows 2000 operating
  system and RSWA software.
• Processor Pentium III with Intel Speed Step
  technology 600/300 MHz
• Main RAM 256MB
• Hard disk drive 2.5 15GB IDE
• Digitizer Resistive
• Display 8.4 TFT/VE-TFT Color SVGA 800 600
  pixels, 8 levels of brightness

23
DSP Board
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RSWA Software

• Common Features
• On-Screen Keyboard
• Login
• Launcher
• Array Explorer

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On-Screen Keyboard
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Login
27
Launcher
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Launcher
Turning Off
Switching Between Applications
Current User
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Array Explorer
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Buttons

• New Inspection starts new inspection file
• Open Inspection opens previously stored
  inspection
• Settings allows changing various application
  settings
• Setup measures front plate thickness
• Get
• push to take a measurement
• push and hold to enter continuous mode
• Size indicator shows nugget diameter

31
C-Scan Area

• Green fused area
• Red no fusion
• Dotted circle estimation of weld nugget
• Small squares push to switch between elements
• Spinning wheel show minimum size indicator
• Hand button manual circle sizing
• IND indentation indicator

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A-Scan Area
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Settings Cont. Mode
34
Settings User Interface
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Typical Welds
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Problems
37
Thank you