What is the difference between Punching and Piercing in Sheet Metal Technology?

Question

Regarding tooling in sheet metal works

Answer 1

In many cases the two terms are used synonymously, however that may not be true depending on your audience.  In some circles,  perforating or punching is generally used to describe all die-cut holes, regardless of their size or shape. In

"Techniques in Pressworking Sheet Metal" by Eary and Reed differentiate between punching and piercing by emphasizing the fact that a slug (the material punched out) is produced in punching operations but not in piercing work.

Piercing often is used interchangeably with punching and perforating operations. However, piercing operations

are frequently (but not always)defined as “forming a hole in sheetmetal with a pointed punch with no metal fallout (slug).”   In this case, a significant burr or deformed sharp edge is created on the bottom side of the material being pierced.  This is not to say the punched material will not have a burr, but the pierced holes will have a significantly more pronounced burr.

Answer 2

Both are processing methods to form a hole in sheet metal.

A punch uses a die that uses a cutting action to remove material from the sheet.

Piercing removes no material and relies on plastic deformation to push a hole through a sheet moving material around the tool.