Definition
A sheet metal forming machine consisting of three adjustable rollers used to bend flat sheet metal into curved shapes such as cylinders or cones. Sheet stock is fed between the rollers, which are set to produce the desired radius as the metal passes through.
Plain English
A shop tool with three rollers that bends flat metal sheets into curves. You feed a sheet through it, and the rollers gradually shape the metal into a curve or full cylinder.
Context Anchor
Seen in aircraft sheet-metal repair and fabrication, especially when making or repairing curved metal parts.
Derivation
The 'slip' refers to the way one of the rollers can be released or 'slipped' out of position so the finished curved part can be removed without having to unroll it. 'Roll former' describes the function: forming metal by rolling it between cylinders.
Why Pilots Care
Pilots usually do not operate this tool, but parts made with it must fit the aircraft correctly. A poorly formed curved repair part can leave gaps, add stress, or make a repair unsafe.
Analogy
It works a little like feeding dough through rollers to make it take on a smooth curve, except the material is aircraft sheet metal and the shape must be controlled precisely.
Intuition Check
Do not confuse “slip” here with an aircraft slip in flight. In this term, “slip” refers to sheet metal being fed through rollers while the tool forms a curve.
Example Sentence 1
The technician used the slip roll former to shape a flat aluminum sheet into a curved engine cowling section.
Example Sentence 2
After damage repair, the new skin panel was passed through the slip roll former until it matched the fuselage radius exactly.