Volume 2, Number 3 July 2003
TNT Tips:
Making Your Own Ultrasonic Calculator
How convenient it would be to have a simple visual tool (calculator) to help identify where your sound is when conducting ultrasonic examination of welds or specimens with complex shapes. Whether your equipment is state of the art incorporating the right angle trigonometry option (assuming both access planes are parallel), or just a "good old unit" that still meets calibration requirements, a simple calculator can be an invaluable tool for the examination of welds and other components.
Assembly:
- You will need a standard size clipboard to be used as the "base plate".
- A sheet of graph paper (I used quad rule 4 X 4 paper). With permanent marker, label x and y axes with appropriate scale (i.e., inches or cm). Select a reference point on the top scale (0,0) to coincide with point of incidence of any transducer you may choose to use. From this reference point use a compass, plus protractor, to draw an arc representing degrees and label points (i.e., 45, 60 and 70 degrees).
- Glue graph paper to base plate (I used basic glue stick), leaving at least 0.25 in. (6 mm) exposed border to base plate. Then cover base plate and exposed graph paper with a single clear lamination sheet. Now use water washable markers to draw the sound path and side orthographic view of the component with dimensions.
- Cut out from a clear stiff plastic stock a piece about 3 in. (75 mm) wide along the length of the stock (I used transparency film). Fold plastic stock at each end so as to wrap around the base plate. I used two rubber bands to hold stock in place. I used this part (I call it the "slider") to draw welds or other geometrical areas of interest to scale. Now, by moving the drawing (weld) along base plate, I can identify dimensions, location, and even classification of flaws with a high degree of confidence.
Not to waste space and to enhance my calculator, I listed general UT equations, acoustic properties of materials, and other handy pertinent information, and then glued this info sheet to the back side of base plate (clipboard) and laminated it. Total cost of materials was less than three dollars and I still use the clipboard as a pad holder for notes. Modifications or improvements are only limited by imagination.
Dan Marks, NDT Engineer
Marks & Associates
Quincy, Illinois
[ The NDT Technician ]
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