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Fixed
PFM BRIDGE CRACKED
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<blockquote data-quote="ztech" data-source="post: 287771" data-attributes="member: 3022"><p>A large bridge with a large amount of ceramics and metal will cool under tension if the <u>alloy doesn't cool first</u>. This will cause cracks that will appear shortly after the firing. Most of us as technicians will try to slow cool the large restoration and it will only make the problem worse. Although in this case you can't redesign the bridge, the best option would be to make the framework with areas of exposed alloy in non-aesthetic areas to allow faster cooling of the alloy. When I have this problem, I do opposite of what has been suggested here, I used the same program as single units, modifying the entry time to allow a more thorough heat up and the time at temp, to allow the mass to come to final temp. From there, i drop to lower table position without a slow cool same as single units.</p></blockquote><p></p>
[QUOTE="ztech, post: 287771, member: 3022"] A large bridge with a large amount of ceramics and metal will cool under tension if the [U]alloy doesn't cool first[/U]. This will cause cracks that will appear shortly after the firing. Most of us as technicians will try to slow cool the large restoration and it will only make the problem worse. Although in this case you can't redesign the bridge, the best option would be to make the framework with areas of exposed alloy in non-aesthetic areas to allow faster cooling of the alloy. When I have this problem, I do opposite of what has been suggested here, I used the same program as single units, modifying the entry time to allow a more thorough heat up and the time at temp, to allow the mass to come to final temp. From there, i drop to lower table position without a slow cool same as single units. [/QUOTE]
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PFM BRIDGE CRACKED
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