Some handy tips and rules of thumb to help you decide the type of guide and installation requirements for your converting process
Roller face width, diameter and surface finish
Selected based on application
Roller face width should be at least more than 2 inches of the widest web material used in the converting operation.
Thicker and composite materials (label+liner) require larger diameter while low tension applications require smaller diameter rollers to reduce roller inertia.
Lower inertia rollers (aluminum or carbon fiber) with free spinning bearings work well even when tension and speed changes are observed.
Grooved rollers, especially with plastics, reduce air entrapment at higher speeds and increase traction to reduce scratches and web slippage.
Smooth rollers are recommended for delicate webs (thin foils) that might get imprints from roller surfaces with grooves.
Entry and Exit Span Lengths
Entry and exit span considerations for displacement or offset-pivot web guides
Displacement web guide can have short entry and exit spans. The entry and exit spans may have different lengths.
The minimum entry span can be between 2/3rd to one full web width for thin and flexible materials. Longer entry spans may be required for heavier and stiff materials.
Ideal wrap angle for the entry and exit spans is 90°.
Entry and Exit Span Lengths
Entry and exit span considerations for steering or remotely pivoted web guides
Steering guides are typically used after a long entry span. 3 to 10x the web widths are typical for most materials. Too short a web span may induce stress that can create a tight and slack edges.
The pre-entry span length needs to be smaller than the entry span length. The wrap angle between the pre-entry and entry span should be at least 45°, while 90° or more is desired.
Ideal wrap angle between the entry and exit spans should be 90°. And the exit span length can be a minimum of 2/3 to 1x web width.
Multiple web path threading options provide easy integration.
Displacement guides are more versatile than steering guides because of the multiple options the two roller guides offer. There are two basic paths through the two rollers that offer a variety of web direction options: U configuration and Z configuration through the two guiding system rollers.
The configurations allow for multiple arrangements of web paths which are convenient in converting processes with available space constraints
Web Edge or Web Contrast Guiding, Converters have multiple options for web guiding.
Web edge guiding is usually referred to as guiding on a single edge of the web material. Web center guiding refers to guiding by monitoring both edges and placing the material in the center of the process. Web contrast guiding provides placement of a material based on a contrast on the material and not on the physical edge of the web. Line guiding is a form of contrast guiding in which the material is placed based on a printed line