Intro
13%
Lubrication application: spray, swab, roller, drip, and why coverage beats volume
Set up a spray bar so coverage is uniform and dwell matches the cycle, tell a wet die from a lubricated die, and read the four classic application failures off the die face.
A shop runs two identical H13 closed-die forge inserts on the same press, same lube, same operator. One reaches 90K hits with stable scrap rate. The other galls in a back-corner pocket at 38K and gets pulled for re-nitride. The pulled die has a clean coverage map on the front half of the impression and a barely-touched matte zone in the corner where the gall started. The lube system on the line was running at the same volume setting for both. The spray bar over the failed die was mounted 15 mm further forward than the spec drawing called for.
Volume was identical. Coverage was not. The die that died saw the same lube as the one that survived, just not on the part of the face that was working hardest.