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This video will address several

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nondestructive tests
that are common in

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the foundry industry for
testing cast components.

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To begin, I’d like to give you some
background on the topic.

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Cast manufacturing is
used for automotive parts,

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heavy equipment, and
other structural components

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with complex geometry.

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Common materials include aluminum,

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iron, and steel, but other
metals may be used as well.

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Cast components are manufactured by

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pouring molten hot metal
into a sand mold.

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The molten metal is then cooled
and solidified,

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forming the part.

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As a result of the
manufacturing processes,

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castings generally end up with
rough surface conditions,

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grainy crystal boundaries,

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and have the potential
for internal defects.

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Due to these characteristics,

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there are a number of
nondestructive testing techniques

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that apply to cast components.

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These include eddy current
tests for surface cracks,

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and ultrasonic tests for thickness,

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porosity and voids,
and graphite nodularity.

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This first example will cover porosity

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and void detection using
the EPOCH 650 flaw detector.

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It’s common for internal
porosity and voids

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to occur in more central
locations within a cast part.

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This is where it takes longest
for metal to cool

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with respect to the outer edges.

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Because of the rough outer surface

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and scattering effects of castings,

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we will use a low frequency
dual transducer

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such as the CHC706-RM
for the inspection.

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This will be paired with a dual cable

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to connect to the EPOCH 650.

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High pulsing power can be used

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to increase sound penetration
into the sample.

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We can detect our production flaws

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by looking for echoes occurring before

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the backwall echo on
our live A-scan display.

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Larger flaws will generate
larger amplitude echoes.

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In some cases flaw sizing techniques

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such as DAC or DGS

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are used in combination
with software options

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like Backwall Echo Attenuator,

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in order to develop an
acceptance/rejection criteria.

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Graphite nodularity testing
in cast iron

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can be done with any instrument

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that is capable of
measuring sound velocity.

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This includes an Olympus
Ultrasonic Flaw Detector,

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Ultrasonic Thickness Gage,

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or a Pulser/Receiver system.

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The practice of adding
graphite to cast iron

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is commonly used to enhance the
materials’ mechanical properties.

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Gray iron is formed
when added graphite

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arranges itself in the
form of thin flakes.

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This results in a more
hard and brittle iron.

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The more desired graphite
microstructure

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is in the form of spherical nodules

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which produces a more soft
and malleable iron.

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This material is known as
nodular iron.

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We can check nodularity by measuring

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the ultrasonic sound velocity
through the material.

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Each material will have a
different sound velocity.

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In order to measure it correctly,

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it is important to know
the true thickness

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of the sample you are working with.

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To perform the test, we will use

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a heavily damped, single element
transducer

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for penetration and accuracy.

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If needed, we can use
high pulsing power

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to ensure sufficient penetration.

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Once a clean backwall is visible,

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we can calculate the material velocity

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based on our known thickness,

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and make sure that the
sound velocity is appropriate.

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This gives us confirmation

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that the microstructure is uniform,

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and that the graphite inclusions
are of the right form.

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These are just some of the
foundry production processes

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that Olympus products can enhance.

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For more details and information,

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contact your local representative,

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or visit us online at
www.olympus-ims.com