Hollow extruder die for extruding a hollow member of a zinc-containing aluminum alloy

A method of protecting an extruding die from cracks due to brittleness caused by zinc when extruding a hollow aluminum alloy section containing zinc, said extruding die having a die mandrel part in combination with a die cap part, said die mandrel part having a main body portion having a through hole passing therethrough with a mandrel, for forming the hollow extruding section, being supported in the through hole by at least one bridge portion that at least partially defines a root portion of said mandrel, and said die cap part having an extruding hole passing therethrough for forming a peripheral portion of the extruding section, said method comprising the steps of:

• making a coating fast with and completely covering said at least one bridge portion and said root portion of the die mandrel part, said coating being resistant to said brittleness caused by zinc and preventing said zinc from contacting said root portion, thereby to resist cracking of said root portion;
• making a coating fast with and completely covering an inner surface of said die cap part;
• positioning the die cap part so that it covers the bridge portion and the root portion of the die mandrel part;
• and
• extruding an aluminum alloy containing zinc through the mandrel part and the die cap part whereby stress is placed directly on the die cap part and indirectly on the bridge portion and the root portion of the die mandrel part thereby extending the life of the die.