Most assembly failures don’t announce themselves at the press. They show up downstream, in a test cell, in a customer complaint, in a warranty return that lands on someone’s desk months after the part shipped. By the time the connection back to a bad press cycle gets made, dozens or hundreds of parts may have already gone out the door the same way.
That was the situation for a manufacturer pressing splined shafts into hubs for rotating equipment, a job that leaves no margin for error once you’re talking about tooth flanks. Their process wasn’t sloppy. It had a spring-loaded pilot designed to guide the shaft into alignment before the press applied force, and most of the time, that pilot did its job. But “most of the time” is exactly the gap that shows up later as noise, vibration, or premature wear, because when the pilot didn’t settle in time, the press had no way to tell the difference between a shaft that seated cleanly and one that ground tooth tips against tooth tips on the way in.
That’s the real lesson underneath this story: a press that only checks force and position at the end of the stroke is checking the wrong things. Force and position tell you the press did something. They don’t tell you it did the right thing.
Confirming alignment changes what the machine is actually deciding.
Instead of pressing on a timer and hoping the pilot found its mark, a closed-loop process can search for alignment directly, and confirm it with the precision to tell true seating from tooth-on-tooth contact, before applying force. In this case, a REMAP unit paired with an UltraPRO controller brings the shaft into light contact with the hub, then rotates it slowly while watching force against rotational position. Misalignment and true alignment produce distinct signatures. The system waits for the right one, locks onto it, and only then completes the seating stroke, with a full record of force, torque, and position for every part.
The part that doesn’t produce a clean alignment signature doesn’t get forced through. It gets flagged. That single change, refusing to press blind, is what turns tooth damage from an occasional surprise into a rare exception.
What this means beyond one part number.
The manufacturer in this case study saw tooth-damage scrap drop by 75–85%, downstream test failures related to spline fit fall to near zero, and cycle times hold steady or improve. But the bigger takeaway applies well past splined shafts: any press-fit or interference-fit assembly where alignment matters more than the machine can currently confirm is a candidate for the same shift, from pressing and checking after the fact, to confirming and then pressing.
If that sounds like a process running somewhere in your plant right now, the Promess Process Development Center can validate expected results on your specific application before you commit to anything.
