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Letter 18040
Ultrasonic / blast cleaning of aluminium
castings
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I am attempting to clean used aluminium engine castings; my
intention is to ultra-sonically clean the castings then bead blast
with glass bead. I have purchased a used ultrasonic tank, however to
date I am have no success with it. As I have never witnessed any
ultrasonic leaning I am a little unsure what to expect. Can anybody
recommend a suitable cleaning solution and operating temperature? The
engines are oily / greasy with embedded road grime: can ultra sound
handle this kind of contamination?
The second part of my question regards the blast media: is there a
better alternative to glass bead? The castings are LM25, if glass
bead is the best can anyone recommend a size / grade? Finally is
there a better way altogether? Chemical perhaps? Vibratory cleaning?
Thanks,
Garry Kemp
- East Yorkshire, United Kingdom
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You've got a couple of issues here. First, your used ultrasonic
tank. How old is it, are you sure it is working correctly and have
you had it checked out? You must see and test for cavitation. Get a
piece of alum foil wrap and place in tank. A good system will in a
short time put holes in foil under .020. A heated tank is suggested
with a chemical additive with a wetting agent. However, your castings
maybe too massive for the ultrasonics to pentrate and work properly.
Normally, ultrasonics are used after blast cleaning parts. You
might want to consider alum oxide or garnet as an abrasive grit, if
the castings are really bad in appearance and contaminates. With
proper chemicals and a good cleaning system, you might be able to do
this in a one step operation.
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