Why Does Aluminium 5182 Need Different Feed Settings?

The Job That Fed Perfectly in Steel and Failed in Aluminium

The evidence was consistent across three coils. Marks appeared on the top surface in a band 40 mm wide, spaced at the feed length.

Feed length drifted by 0.25 mm over 300 strokes, always short, never long. That pattern points to slip rather than to encoder error.

Strip edges showed a slight burnish, which the tool room read as guide contact and the line team read as normal.

Two departments, two explanations, and neither one addressed the material. That is where most aluminium feeding problems begin.

Three Properties That Change the Setup

Work hardening is the first. 5182 hardens quickly under strain, so every pass through a roll changes the material the next pass sees.

Galling is the second. Aluminium transfers to steel roll surfaces under pressure, and the transferred layer then marks the next metre of strip.

Springback is the third. The elastic recovery of 5182 after bending is larger than mild steel at the same yield, so the same penetration produces less permanent set.

Each of those maps to a specific setting: penetration for springback, roll pressure for galling, and pass scheduling for work hardening.

Hardness and temper are the two numbers worth requesting. A 5182 coil at H32 behaves nothing like one supplied at O temper.

Coil set matters more on aluminium because it yields at lower stress, so a set that would relax in steel simply stays in the strip.

Camber from slitting is the third thing to check. It arrives looking like edge wave and gets blamed on the straightener within a shift.

Ask the mill for coil set and camber limits in millimetres per metre, then reject anything outside the norm you have measured on your own line.

Adjust one without the others and the improvement moves the defect rather than removing it.

Feed Roll Pressure Has to Come Down, Not Up

The instinct on any feed problem is more pressure. On aluminium that instinct is the cause of the problem.

Excess pressure embeds aluminium into the roll surface. Once that layer forms, every subsequent part carries its imprint until the roll is polished.

Pressure should be the minimum that prevents slip, established by a slip test at the fastest speed in the schedule, not by feel.

On 1.2 mm 5182 a typical setting is 60 to 70 percent of what the same gauge of mild steel needs, because the material conforms to the roll more readily.

Wipe the rolls at every coil change during the first week. The transfer layer builds faster than most operators expect and is far easier to remove early.

Two operators setting pressure by feel will produce two different results, which is why the slip test matters more than the gauge reading.

A slip test takes ten minutes. Mark the strip and the roll, run 50 strokes, and compare commanded length against measured length.

Straightener Settings: Less Penetration, More Roll Contact

Springback means the strip needs more bending to reach the same permanent set, so penetration generally goes up, not down.

That is the opposite of the feed roll advice, which is why the two settings have to be reasoned about separately on aluminium.

Roll contact improves flatness on aluminium because the material is more sensitive to local pressure variation across the width.

On a five-roll head running 1.2 mm 5182, one extra half turn of penetration at the entry pair usually removes the centre buckle that appears otherwise.

Watch the exit pair instead. Over-penetration there puts a permanent curve into the strip that the die then has to flatten.

Roll diameter has an outsize effect here. A small roll bends the section through a tighter arc and work hardens the surface more per pass.

Worked Settings for 1.2 mm 5182

The table below is the setup that ran clean for eleven days on this job, 1,000 mm wide, 1,200 SPM strokes, 320 mm feed length.

The speed reduction is the least popular line in that table and the one that kept quality stable across three shifts.

It is also temporary. Once the roll surfaces are conditioned and the pressure is right, speed can usually return to 175 SPM without marks.

Where the Same Settings Still Mark the Surface

Roll condition sets the floor on achievable surface quality. A roll with a polished chrome finish behaves differently from a ground steel roll on aluminium.

Lubricant choice matters as much as pressure. A lubricant designed for steel may not leave a film thick enough to separate aluminium from the roll.

Ambient conditions contribute too. Aluminium picks up moisture films differently, and a humid summer week can bring back marks that disappeared in winter.

And a die that strips hard will pull the strip against the feed rolls, which no roll setting can fully compensate for.

Treat the settings as a starting point validated on your own rolls, not as a specification transferable between machines.

Changing Over From Steel: A Four-Point Checklist

The coil line range lists roll diameter and roll count per model, and both figures decide how much of this checklist you have to work through.

A machine with large rolls and few of them needs different treatment from one with nine small rolls at close pitch.

• Ask for temper, coil set and camber limits with every coil, not just the alloy designation.
• Set feed roll pressure by slip test at maximum schedule speed and record the value on the machine.
• Polish the feed rolls and the straightener rolls before the first aluminium coil, not after the first complaint.
• Run a slip test at maximum schedule speed and record the pressure at which slip begins, then set 10 percent above it.
• Increase entry penetration in half-turn steps until centre buckle disappears, then back off one step.
• Wipe rolls at every coil change for the first week, then extend the interval based on what you actually see.
• Log the settings against the coil number, so a repeat order starts from a known point rather than from scratch.

That checklist takes ninety minutes and saves the three days of experimentation that this job actually consumed.