Coil Coating

Litho Strip Pretreatment


Consistent process parameters are the key for good pretreatment of high-grade surfaces and thus a prerequisite for optimum product quality. Eisenmann is the leading supplier of pretreatment plants for litho strips, which set standards in terms of product quality.

In the production of litho strips, an effective pretreatment, in this case cleaning and activating, are indispensable requirements for the downstream coating with photosensitive material. Based on comprehensive process know-how, Eisenmann has developed the appropriate plant engineering systems to be able to implement the extraordinarily high demands on the surface properties such as roughness, uniformity and hardness in an optimum and reproducible way.

The cleaning process

The aluminum strips are cleaned by being passed through a multi-stage washing chamber in loops. An alkaline cleaning agent with pickling properties supports cleaning the strips of adherent rolling oils. Oil remains and cleaning agent are rinsed off in the downstream rinsing zones.

A nozzle system provides for an even distribution of the cleaning and pretreatment agents on the upper and lower sides of the aluminum strips. The use of spoon-type nozzles with a large bore hole minimize the risk of contamination and thus the maintenance effort.

The spray bars of the degreasing zone are combined to multiple spray bar groups that are automatically switched on or off depending on the feed speed. The media are circulated via a degreasing bath that is cleaned by means of an ultrafiltration system.

The rinsing area is subdivided into multiple zones, ending in a final DI water zone. An intelligent cascade provides for minimum water consumption and operating costs. The combination of squeegee rollers and pre-spraying bars minimizes the bath carry-over, thus ensuring sufficient dilution using only 3 rinsing zones; compared to traditional solutions involving 6 zones, 3 zones and the corresponding space required for these 3 additional zones can be saved.

For more detailed information and further data, please refer to the data sheet lithographic strip cleaning.

For the subsequent step of electrolytic roughening and anodizing, Eisenmann can also produce several reference plants.