Schmitz
The Schmitz is a mistake in the printing process , which manifests itself in the form of a smeared print and a blurred print image.
Among others there is the roller smith and cylinder or dress smith . With roller smithing, the inking rollers slide on the guide rails, for example due to oil or grease on the rollers or due to different diameters, so that the peripheral speed of the roller is lower or higher than that of the shape below it . The cause of roller smear is usually excessive wear on the rollers or races, so that the diameters differ. The roller is therefore inevitably rotated faster or slower than the bearer ring on the circumference and thus pushes over the mold instead of rolling on it. As a result, the color is not transferred by splitting, but by smearing and the shape is not colored evenly. In extreme cases, the paint is literally rubbed off again and the form remains bare.
Bogenschmitz , also called Druckabwicklungsschmitz , comes about when the lift is too strong or too weak. The sheet is then drawn or compressed over the form with a relative speed not equal to zero ( development error ).
Flugschmitz or Fallschmitz is caused by the sheet not resting tightly on the impression cylinder or by a paper that is too wavy.
Toothed strip smear is caused by leaked cylinder bearings or incorrect grip of the gear wheel pairings of the drive.
Schmitz appears in the print image as an edge deposit of the printing ink on one side of the letters or images. The position of the smear edge is parallel to the axis of rotation of the crucible or cylinder and primarily at the roller contact point. Visible height deformations also occur in the printed typeface as distortion in the direction of travel.
Schmitz differs from smearing in that it cannot be traced back to sheetless or insufficient pressure adjustment (force adjustment) and always occurs in the same place and on the entire printed image.
In rotogravure printing , Schmitz can usually be recognized by blurred and sometimes double contours. Here the error mainly occurs due to wavy sheets of paper, fluctuating paper webs, impression rollers that are not evenly aligned and incorrect handling between the impression cylinder and the printing forme cylinder.
Schmitz permanently destroys the rollers and leads to premature mold wear. It can be turned off by strictly adhering to the lift heights and precise setting of the inking rollers .
See also
literature
- Dieter Liebau, Hugo Weschke: Polygraph specialist lexicon of the printing industry and communication technology . Polygraph Verlag, Frankfurt am Main 1997.