How Much Misregistration Should a Label Press Allow?
Hold colour-to-colour register near 0.25 mm, and print-to-die near 0.5 mm, on an ordinary narrow-web label. Tighten both when a border, a small label or a regulated product makes that shift obvious. One published converter specification uses ±0.010 in between colours and ±0.020 in from the first colour to the die. Put the inspection alarm inside that window and the stop at the window.
The short answer
Use two limits, not one.
For an ordinary narrow-web label, hold misregistration to about 0.25 mm between colours and about 0.5 mm from the first printed colour to the die. A border, a label under about 25 mm, or a pharmaceutical or security product should be tighter, and the number belongs in the job ticket before the plates are made.
Those starting figures are not an ISO tolerance. They match a published converter specification: ±0.010 in (0.254 mm) from the first colour to the colours after it, and ±0.020 in (0.508 mm) from that first colour to the die cut.
What the measurement is actually of
Register is a position, so it needs a reference. "It looks shifted" is not a measurement.
Colour-to-colour register is the movement of each later colour relative to the first printed colour, along the web and across it. Print-to-die register is the movement of the cut relative to that same first colour. A press can be perfect on one and outside the window on the other: the print decks tracked each other, and the die station did not.
Measure on a finished, flat label, from a straight printed edge that is parallel to the cut. On a shaped label, pick the point where the graphic comes closest to the cut. A loupe scale readable to 0.1 mm is enough for a manual check. An inline camera should report both directions, not a single "register error" that hides which way the web moved.
A window you can write on the ticket
IDENTCO publishes these as its standard label manufacturing tolerances. They are a useful default when the customer has not named one. They are not a promise that every press will hold them at every speed.
| Check | Limit | In millimetres |
|---|---|---|
| Colour to colour, from the first printed colour | ±0.010 in | ±0.25 mm |
| Print to die, from the first printed colour | ±0.020 in | ±0.51 mm |
| Die to die, between cutting tools | ±0.020 in | ±0.51 mm |
Flexographic design guidance from FIRST tells the designer to confirm print-to-print and print-to-cut with the printer, because a central-impression press, a stack press and an in-line press do not drift the same way. Treat the table as the place you start the argument, then replace it with the number the brand owner will actually measure.
The same 0.5 mm is a different defect
Take a 25 mm square label with a 1 mm printed border. A 0.5 mm print-to-die shift leaves 0.5 mm of border on one side and 1.5 mm on the other. Half the border has gone. The job is outside the window above, and it looks it.
The same 0.5 mm on a 100 mm label with a 4 mm clear margin moves the graphic, but the eye often accepts it. Copying the loose job's limit onto the small one is how a "press that always passes" starts shipping crooked borders.
So write the limit from the smallest element that touches the cut or another colour: a hairline border, a two-colour word, a register mark that sits in the gap. If two colours of text can collide, keep them more than twice the trap apart. A modern servo press can hold well inside 0.25 mm. That capability is not the customer tolerance. Set the tolerance from the artwork, then ask whether this press, this substrate and this speed can hold it.
Where to put the alarm
- Name both references on the ticket: colour-to-colour, and print-to-die. Say which colour is the reference.
- If the customer has not given a number, start from the table and tighten it for a border or a small label. Do not invent the number after a complaint.
- Set the inspection alarm at about 70% of the window, so someone corrects the press before copies are lost. On the table above that is about 0.18 mm between colours and 0.35 mm to the die.
- At the window, stop the press or flag the roll. Flagging is enough for a rewinder that will splice the bad repeats out. A pharmaceutical or security job usually needs the stop, because 100% inspection is there to prove the defect did not leave.
- Keep web direction and cross direction separate. Tension and repeat-length growth move the print along the web. Side-lay and die alignment move it across the web. One combined number sends the operator to the wrong knob.
Colour is a different check. A sheet can be inside this register window and still fail a Delta E tolerance. Do not let a green register light close the colour argument.
Where to go next
- Misregistration defines the defect and the usual mechanical causes.
- 100% inspection is the check that sees the repeats between manual pulls.
- What is print quality inspection? puts register next to colour, spots and missing print.