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铝挤压成型工业
- Aluminum Extrusion Dies
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In current industrial practice, aluminum extrusion plants commonly use nitriding
to surface-harden dies. Apart from the initial treatment, nitriding is used to
recondition the working surfaces of dies after a number of extrusion runs, when
the nitrided case has suffered damage through wear and prolonged heating.
Depending on the profile thickness and complexity, this re-nitriding operation
may be repeated many times.
TIPS
1:
A most serious factor causing deterioration of the nitrided surface is prolonged
preheating in air. If the time of preheating is limited to approximately 4
hours, or at least not more than 5 hours, this initial deterioration is not
significant.
2:
A better method of limiting the destructive effect of air oxygen would be to
preheat dies in a protective gas atmosphere, for example in nitrogen. Protective
atmospheres prolong the allowable pre-heating time and protect the nitrided
surface against oxidation. (See
Die Preheat Ovens)
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