Converting applications will typically require some type of guiding. It can be in the form of terminal or intermediate web guides, each with the peculiar conditions required to provide an effective placement of the web guide. However, all these applications are used in environments subject to atmospheric conditions. One of the most challenging web guiding applications deals with vacuum web guiding.

In negative space web guiding dealing with the consistency of the negative space is the same as if we were dealing with the consistency of a printed line for line guiding. 

The line has to be of the same width and color in order for the sensor to track it. Any variation and the sensor will not recognize it. The same thing happens when using the negative space as guiding feature.

Issues in Negative Space Web Guiding as Substitute for Line Guiding 

In a previous post we presented the concept of negative space web guiding as an option to line guiding. We are talking about using the negative spaces between printed features, such as the separation between labels. This application does come with its challenges.

Line guiding is one of the subsets of contrast sensing applications.

It requires the printing of a line on a web. It's purpose is to provide a feature that a sensor can track to determine the web position. The typical use is in web converting where guiding on the edge might not be a precise parameter in printing labels. However, printing a line is an additional cost. After all, it is additional ink. If the line is printed outside of the main printed features of the web, it could be leaving money in the converting floor in the form of excess trim on the edges of the web.

So far, we have looked at the web guide mechanism, actuator and sensor. The remaining component of a web guiding system is the web guide controller. 

End and Center Pivot Guides - Not a commonly used web guide in the industry

End and center pivot guides do not displace the web, they only have the angle of rotation to reposition the web. This makes them very slow in term of response, and therefore, are not an ideal choice in web guiding options.