Adjusting an iron's loft or lie angle at the hosel with a bending machine, fitting the club to a golfer's swing without changing the head. A bending machine clamps the head and levers the hosel to open or close lie angle (how upright or flat the sole sits at address) or strengthen/weaken loft, typically in half-degree steps. Forged irons, made from softer carbon steel, tolerate the most movement — often 4 degrees or more of lie and up to 2 degrees of loft before risking hosel stress; stainless steel cast heads are far less forgiving, and some cast or multi-material models are flagged non-bendable because the head can crack rather than flex. The 2-degree loft ceiling exists because bending loft also tips the sole angle and changes turf interaction; lie bends alone don't have that side effect, which is why fitters allow more room there.