Forging Defects Class Process Treatment

Aluminum alloy head screw blank mouth deviation and wall thickness variation exceeding tolerance.

Material: 7A04-T6.

Failure background: During the production of larger size head screw blanks using aluminum alloy rod material through the reverse extrusion forming process, more than 40% of the blanks exhibit mouth deviation and wall thickness variation exceeding tolerance, as shown in the figure.

Failure characteristics: The mouth deviation of the blank leads to an overall length shortage; the wall thickness variation exceeding tolerance results in insufficient machining allowance.

Failure cause: The length-diameter ratio of the blank material exceeds 3, hence the reverse extrusion forming process scheme of the rod material is not suitable for the production of larger size head screw blanks.

Correction measures: The technology of "tube material necking and die forging composite precision forming" is adopted, replacing the process scheme of "rod reverse extrusion forming."