Toner Marking
Toner marking can be a problem for friction feeders and belted accumulators. Friction is the primary cause. In the feeder, friction separates sheets. Marking comes from the singulator roller, retard roller, output rollers and the tractor belts that help drive the paper. Continuous form documents partly escape this fate because there is no feeder. However, accumulation before folding is the norm for transactional documents. Documents are marked in the accumulator which most often has belts that help guide the paper and output rollers which drive the paper from the accumulator to the folder.
Documents with large logos, toner-based color and duplex printing are most susceptible to marking. Marking defeats the purpose of the document especially in this new "trans-promo" world where personal means no signs of automation. Some marking will always occur with such systems. There are ways to minimize marking and there are other products on the market with different technologies that have less of a tendency to mark.
Document design has an impact. Logos and large areas of toner should be located away from the primary marking causes instead of directly under them. This requires a flexible marketing department. Toner-based printers can be the subject of more frequent periodic maintenance. Marking often seems to become more severe near the end of a maintenance cycle when toner is not adhering as well to the paper. The new high quality production ink jet printers are another solution. Ink soaks in. Toner sits on top. Another solution available for some toner based printers is coating. Coating protects the print. It is especially important for duplex color documents.
Of great importance for friction based finishing systems is regular periodic maintenance and cleaning to reduce the build-up of toner on belts and rollers, reducing the amount of toner transferred to documents. Ensuring that the belts and rollers are in good shape improves feeding putting less pressure on the paper by minimizing slippage. Clean belts and rollers have less toner to leave on documents. Cleaning should occur at the end or beginning of every shift. Ten minutes of cleaning a shift makes a difference.
System speed can have an impact. Sudden starts and stops can dislodge toner, especially where adhesion is poor.
Different finishing hardware also helps. For cut sheet systems, vacuum bottom feeding is much less likely to mark. Also, some vendors offer devices that separate the belts from the paper just enough to substantially reduce the marking. There are also other accumulation before folding technologies in some products that have the same effect. One such technology is accumulation in the fold plate. This technology also improves throughput by shortening the distance the paper travels during the accumulation process.
All of these technologies will be shown at Graph Expo in
This article was written by Jeffrey H. Brewer, Vice President & General Manager of GBR Systems Corporation. GBR is a wholly owned subsidiary of Mathias Bäuerle GmbH who may be seen on the following web sites: www.mb-bauerle.de and www.gbr.com.
