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. 

So far we have discussed the different types of web guiding systems for converting applications. You now should know the different types of web guiding systems, and their design and installation recommendations. Also, you should have an idea of why web guiding is needed and where they should be installed in converting operations. In this blog post we will address a component of a web guiding system, the web guide actuators.

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.

Within the group of terminal web guide systems, there are two basic types: Unwind web guide systems and rewind web guides systems.

Both systems have basically the same components, but they work differently. Let’s look at the unwind web guide structure.

A web guiding system for converting operations has four main components:  

• Guide Structure/Mechanism
• Actuator
• Sensor
• Controller

However, even though we mention four main components, the web has to be considered a component of the web guiding system.

Most web guides work on the fundamental principle of Normal Entry.

This rule states that a web approaching a roller will align itself perpendicular to the axis of rotation of the roller. The Normal Entry principle accounts for one of the most common defects in a converting line, roller misalignment. If your converting line has one roller that is not correctly aligned perpendicularly to the required path of the web, the web will move in order to be perpendicular to the misaligned roller.

Intermediate Web Guides

Used before a critical process in the converting line 

In our previous post on web guiding fundamentals, we mentioned the terminal web guides. These are web guides that are found at the start or the end of the process. Their location is usually on an unwind or a rewind stand. As we discussed, their installation depends on whether the guiding system is used for unwinding a roll of web or rewind a processed web into a roll.

The web at the start and end of your converting line needs to be properly aligned to have a good conversion process and a well wound roll for your customers

It's an advantage to know what you are dealing with when aligning your web as it enters your converting process or is being wound into a processed roll. Here's some information that should be of help to you.