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Application Notes
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Measuring Thickness of Wax Molds for Precision Castings

In lost wax casting, a process through which wax patterns are dipped in a ceramic slurry and then burned out to create a mold, precise dimensions of the wax pattern are extremely critical. If one side of the wax pattern is difficult or impossible to reach, ultrasonics may be the only method to measure its thickness. Wax patterns for cast turbine blades are good examples: the pattern thickness is crucial in order to produce cast blades that are within specifications.
With an ultrasonic gauge, the thickness of the wax can be measured without destroying it. Some wax patterns are formed around ceramic cores. This is an important distinction because sound that is reflected from a wax-ceramic boundary reacts differently than sound reflected from a wax-air boundary. Although both measurements can be made, they require separate setups. We should be informed which setup is needed; in general, samples are required to enable our office to recommend the correct instrumentation.

Equipment: The Olympus precision thickness gages are normally recommended for wax mold measurement. These include models 38DL PLUS and 45MG with single element software. The recommended transducer depends on the thickness and geometry being measured. If the application includes wax over ceramic, accurate measurements rely on good bonding between wax and core without areas of disbond. Wax over ceramic requires a special gauge setup (echo polarity inversion); these setups will result in less accurate thickness measurements when the wax is partially or totally disbanded. Some complex geometries such as sharply radiused turbine blades may require use of a focused immersion transducer and bubbler. In such cases is often recommended to insure proper sound beam alignment.

Olympus IMS

Products used for this application


The 38DL PLUS is an advanced ultrasonic thickness gage. Uses dual element transducer for internal corrosion applications, and has features that include THRU-COAT technology and echo-to-echo. Uses single element transducers for very precise thickness measurements of thin, very thick, or multilayer materials.


The handheld 45MG ultrasonic thickness gage is packed with measurement features and software options. This unique instrument is compatible with the complete range of Olympus dual element and single element transducers, making this gage an all-in-one solution for virtually every thickness gage application.

Magna-Mike 8600

The Magna-Mike is a Hall effect thickness gage that uses a magnetic probe to perform accurate measurements on nonferrous and thin materials such as plastic bottles.
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