Sacrificial sleeves for die casting aluminum alloys

A method of die casting an aluminum alloy article of predetermined composition and having an internal round cylinder wall surface, the round cylinder surface having a predetermined internal diameter and height, the method comprising:

• providing a die casting tool having a round cylinder surface portion, the round cylinder portion having a height for forming the round cylinder surface of the article and a diameter smaller than the internal diameter of the cylinder surface;
• placing a hollow round cylindrical liner on the round cylinder tool surface, the liner having a height and an outer surface with an outer diameter for defining the internal round cylinder wall surface of the article;
• casting a melt of the aluminum alloy against the outer surface of the liner, the melt solidifying against the liner surface and bonding to it, the thickness of the liner being predetermined to resist melting or deformation by the cast aluminum alloy before the cast alloy solidifies;
• removing the cast article and bonded liner form the die casting tool;
• and
• machining the entire cylindrical liner from the internal surface of the cast article to form the round internal cylindrical surface of the article.

A method of die casting an aluminum alloy article or magnesium alloy article of predetermined composition and having an internal cylindrical wall surface, the cylindrical wall surface having at least one predetermined internal cross-section dimension and a height, the method comprising:

• providing a die casting tool having a cylindrical surface portion, the cylindrical surface portion having a height for forming the cylindrical surface of the article and a cross-section smaller than the cross-section of the cylindrical wall surface;
• placing a hollow sleeve liner on the cylinder surface portion of the tool, the liner having a thickness, a height, a cross-section shape, and an outer surface for defining the internal cylindrical wall surface of the article, the hollow liner being formed of an aluminum alloy or magnesium alloy corresponding to the alloy of the cast article;
• casting a melt of the aluminum alloy or magnesium alloy of the article against the outer surface of the sleeve liner, the melt solidifying against the liner surface and bonding to it, the thickness of the sleeve liner being predetermined to resist melting or distortion by the cast alloy before the cast alloy solidifies;
• removing the cast article and bonded sleeve liner from the die casting tool;
• and
• machining the cylindrical liner from the internal surface of the cast article to from the internal cylindrical surface of the article.