Defects in Metal Material Forming Processing, Part 9

Defects in metal forming processes can arise due to various factors, including material properties, process parameters, and environmental conditions. Here are some common defects associated with metal forming:

Peeling and burring

The local cracking and bulging of the product surface is called peeling. The needle-like metal filaments on the surface of the product are called burring.

Peeling or burring are generally distributed continuously or intermittently along the rolling direction, and the peeling area often has oxide scales or other dirt, inclusions, etc.

The peeling of tubes and bars generally forms tongue-shaped and fish-scale-shaped bulges along the processing direction. Severe ones penetrate the entire product, and severe ones form scars locally. Burring often occurs in the last process of rolled products.

The main causes of peeling are: defects in ingots and uneven surfaces; excessive processing temperature causes oxidation of the product surface or defects in the surface caused by the previous process; water, oil and other dirt on the rolls, in the extrusion barrel, and on the piercing needles; defects in processing tools and mechanical damage during processing.

The main causes of burring are: cracks in the rolls; uneven edges of the billets, irregular depressions, etc.