Slitting & Rewinding Why your slitter’s productivity
figures are probably wrong By Alan Jones, CEO at Universal Converting Equipment Ltd
A
sk a converter how productive their slitting operation is and you will usually be given a speed. 800 metres a minute, 1000 metres a minute. It is
the number on the specifi cation sheet and the number quoted in the boardroom. It is also, in most converting halls, close to meaningless. The running speed of slitter rewinder only matters for the proportion of the shift the machine is actually running. In operations we visit, that proportion is frequently far lower than the production fi gures suggest. The rest is job changeover, roll set removal, re-coring, threading and the corrective work that follows a badly wound set. A machine capable of 1000 m/ min that runs for three hours of a shift is a slower machine than one capable of 600 m/min that runs for six.
WHAT SHOULD BE MEASURED INSTEAD At Universal, we ask converters to record three numbers over a fortnight. None require new instrumentation. The fi rst is metres slit per shift, not metres per minute. It exposes more than any speed rating, because it contains every stoppage.
The second is the ratio of
setup time to run time per job. When a setup takes 45 minutes and the job runs for four hours, the overhead is around 15 per cent. As run lengths shorten, that same 45 minutes becomes 30 per cent, then 50. The setup did not get worse. The job got shorter. The third is the number of fi nished roll sets per shift and the stopped time attached to each. Twenty roll changes at four minutes each is eighty minutes of a shift, and no operator experiences it as a problem.
THE SAFETY COST NO ONE IS COUNTING The number that surprises converters most is how much of their stopped time exists for a safety reason.
For years, turret slitters were considered the mark of high productivity: while one shaft wound, the operator unloaded fi nished rolls and prepared cores on the other. Today’s regulations prevent that mode of operation. Working on the non-winding shafts while the machine runs
requires the speed and torque of the winding shafts to be limited so severely that the machine is eff ectively stopped.
We believe those regulations exist for good reason and should be adhered to rather than worked around. But it means the productivity case for a turret machine has quietly disappeared, while many converters are still measuring against it.
The only way to make a process genuinely safe is to remove the need for an operator to undertake the risky work at all, and that is also the only remaining route to the stopped time. Safety and productivity are not a trade-off . They are the same engineering problem.
DESIGNING THE TIME OUT
The Universal X8 Slitter Rewinder was developed against that question rather than against a speed target. No operator needs to approach the machine while it is running.
A twenty knife set is positioned, with automatic control of depth and sideload, in under two minutes, and the next set of widths can be entered while the current job runs. Rotary shear or razor blades are positioned precisely and moved away during threading, with a fully enclosed position for the razor holders that removes the cut hazard without the operator handling the blade. Finished rolls are cross-cut, closed and unloaded automatically, then cores are loaded and positioned, and the web is attached automatically; the machine restarts unattended. The next set is to remove the repetitive lifting of cores and heavy rolls, where operator injury accumulates, the universal off er has many options for this, including a full automation system that goes right through to palletising of fi nished rolls.
THE BOTTOM LINE
Speed is the easiest thing to specify and the least useful thing to compare. Before your next machine evaluation, measure metres per shift for a fortnight, and mark which stoppages exist because someone has to walk up to the machine. Most converters fi nd that gap is far larger than any diff erence between two suppliers’ speed ratings.
At Universal Converting Equipment, we would rather sell you total production throughput than top speed in metres per minute.
26
September 2026
www.convertermag.com
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