Feeder Guide

Two identical NC servo feeders can hold different accuracy because of the surface of their feed rolls. This guide compares hardened steel, polyurethane, hard chrome and tungsten carbide on grip, marking and wear, gives expected stroke life for each, and explains how to write roll coating into a purchase order. It also covers five faults a coating change cannot fix.

A single-speed NC servo feeder takes three to four days to commission properly, and a high-speed line with servo pilot release takes five to six. This article walks the eight steps in order with a time budget.

This field case traces the loss from a failing hole-position gauge back to a tacky film on the feed rolls, sets out the four-point check that found it, and states what an NC servo feeder cannot recover by adjustment.

A line rated at 300 strokes a minute would not hold feed length above 180, because the setting sheet had been copied from a 150 SPM job. This is the six-step method for timing an NC servo feeder to a press.

Wide coil exposes a weakness that narrow strip hides: one driven roll pair grips the centre and lets the edges float. This compares single-drive and dual-drive NC servo feeder builds on grip, flatness etc.

Two identical feeders, one holding tolerance at 200 strokes a minute and one losing 0.3 mm above 140, differ in acceleration demand rather than motor size. This works the index time budget on a 55 mm feed...

The free loop between the coil and the feeder is a buffer with a capacity measured in millimetres of strip. This is the sizing arithmetic on a 2.0 mm strip at 120 strokes a minute.

Narrow strip has a fraction of the torsional stiffness of wide strip, so the same machine behaves differently. This is the five-step setup that keeps 60 mm strip tracking, what each failure mode costs in speed.

Feed accuracy is not a single number from a specification sheet. It is a budget shared by servo positioning, roll slip, loop and back tension, lateral position and pilot release timing. This guide breaks down the error sources by typical contribution and cost of reduction, explains what the servo axis can and cannot control, and sets out the verification tests that predict line behaviour.

Slip that starts in the last third of every coil is a load problem rather than a wear problem. Two mechanisms raise the load as the coil pays down, four causes are separated by one speed test, and five fixes that hold.

A four-input calculation that any engineer can run in ten minutes, worked through on a 2.0 mm strip. It also shows the point where a larger motor stops buying anything, because the limit has moved to grip force rather than torque.

Why an over-tight roll gap degrades accuracy instead of improving it: the four signs of over-clamping, gap multipliers by material and thickness, a five-minute verification at the machine, and three problems that only look like gap faults.

A field diagnosis of strip buckling between the feed rolls: why roll pressure, gap parallelism, back tension, material thickness and motion profile each contribute, and a six-step sequence that isolates the real cause.

How to pick a feed roll coating from the strip you actually run: the four coating families compared, why grip and wear resistance pull against each other, and the six signs that the coating has already failed.