Revising the die as soon as a cut appears shifted can make the wrong cause permanent. First determine whether the displacement repeats in one direction and amount, or varies across sheets. The same distinction is the first step of the file assessment for a print-register cutting die order.

Separate constant shift from variation

A repeatable shift in the same direction can point to artwork-dieline reference, die placement or a fixed register setting. If the shift changes sheet to sheet, print position, sheet dimensions, moisture or feeding behaviour become stronger candidates.

In practice the separation is made with ten sheets: consecutive sheets are aligned on the same corner, stacked, and the position of the cut line relative to the print is measured on each one. If the numbers agree, the die side is examined; if they scatter, the press and sheet side come forward.

  • Ten consecutive sheets are measured aligned on the same reference corner.
  • A constant offset points to die placement, a variable one to feeding and the sheet.
  • The measurement direction (fore/aft, left/right) is recorded the same way on every sheet.

Compare four references together

Place the approved artwork PDF, production dieline, full printed sheet and cut blank in the same orientation. If reference corner, gripper allowance, sheet size and marks do not agree, measuring the product contour alone is insufficient.

The reference that slips most often is the gripper margin: when the print layout is built from the page centre and the dieline from the product centre, the two files overlap on screen and drift on the press. The comparison therefore starts from the sheet’s reference corner, not from the product contour.

  • Print PDF and dieline must use the same sheet size and gripper margin.
  • Reference corner and register marks must sit in the same place on all four documents.
  • The sheet reference, not the product contour, is where the comparison starts.

Verify die geometry independently

Measure the cutting contour on an unprinted test sheet. If critical rule distances match the drawing, moving the die to compensate for a file or print issue creates a new error on the next run. Isolate the source before changing one variable.

A contour cut on unprinted stock tests the die independently of the print: if the critical rule distances match the drawing the die is right and is not moved. Shifting the die to cover a print error comes back as a new offset on the repeat order and on a different print batch.

  • The contour is compared with the drawing on an unprinted sheet.
  • If the die matches the drawing, the file or the print is corrected, not the die.
  • Only one variable is changed per trial.

Keep a record of the proof

Retain the first sheet, corrected sheet and approved sheet. Record press setting, reference used and observed displacement on the job ticket. A repeat run can then start from verified evidence rather than a fresh diagnosis.

The record is kept with three sheets: the first sheet, the corrected sheet and the approved sheet, all filed with the job ticket. On the next run the press setting and the reference used are read from that record, and diagnosis starts from a verified point instead of from zero.

  • First, corrected and approved sheets are kept with the job ticket.
  • Press setting, reference corner and measured offset are written down.
  • The repeat run starts from that record without a fresh diagnosis.

Application note

Send two complete printed sheets, a cut sample and the final files so the source of the shift can be separated.

  • Use the real production substrate and final file revision.
  • Correct one variable at a time.
  • Keep the approved sample with the job record.