Edge Guiding

Once the guide is mounted, commissioning is a short menu sequence on the controller: set sensor orientation, check jog direction, servo-center, set the guide point, and switch to Automatic. This is particularly valuable for converters running short production runs with frequent changeovers—there is no need to move sensors or recalibrate when switching materials or web widths.

Roll-2-Roll® Sensors achieve 0.0635 mm (0.0025 in) hardware resolution with ±0.127 mm (±0.005 in) repeatability, and hold it across all material types without recalibration. For comparison, this resolution is approximately the thickness of a human hair. The sensors also feature linearity error of less than 0.25% across the full sensing range.

Yes. Roll-2-Roll® Sensors detect clear films using infrared light reflection. Even transparent materials reflect a small amount of infrared light, which the sensor's CMOS line camera captures and the controller's adaptive edge detection picks out. This is an advantage over ultrasonic sensors, whose readings shift with temperature and which can't work in vacuum, and over infrared sensors that typically need recalibration for different films.

Roll-2-Roll® Sensors use patented fiber-optic technology with adaptive edge detection algorithms. Unlike ultrasonic sensors that measure sound reflection (affected by material density and porosity) or simple infrared sensors that require threshold adjustment,  [rr sesors] use spatial light filtering to detect edges regardless of material properties. The fiber array captures scattered light from any material, and the controller's adaptive edge-detection algorithm adjusts to its reflectivity and transparency, so no recalibration is needed—whether running clear films, opaque substrates, metallic foils, or porous nonwovens.

Electronic guide point adjustment drastically simplifies product changeovers by eliminating the need for operators to physically reposition sensors when the web width changes. Instead of unlocking, moving, and re-locking a sensor hardware assembly, the operator simply changes the target position setting on the controller's touchscreen interface. Better yet with Roll-2-Roll® Controllers this can be completely automated with remote guidepoint adjustment either via industrial ethernet or digital I/O inputs.

Electronic guide point offers three specific benefits for product changeovers:

1. Elimination of Mechanical Adjustments & Safety Risks: In traditional "single edge guiding," a width change requires the sensor to be physically moved to the new edge location. This often forces operators to climb into the machine or reach into hazardous areas to adjust brackets. By using Roll-2-Roll® Sensor (e.g., 48mm to 960mm sensing window), the sensor remains fixed to the machine frame, and the "guide point" is moved electronically within the sensor's viewing window. This removes the operator from the machine, improving plant safety.
2. Reduction of Operator Error & Waste: Physical sensor repositioning is prone to human error. If an operator locks the sensor in the slightly wrong position, or if the sensor bracket is not rigid, the web will be aligned incorrectly, leading to immediate material waste. Electronic adjustment allows for precise, digital settings (e.g., 0.25mm increments with Roll-2-Roll® Controller) that are repeatable. Furthermore, these settings can be pre-programmed based on product codes, allowing for "recipe-based" changeovers where the guide point updates automatically without human intervention.
3. Removal of Mechanical Wear: Legacy systems sometimes use "sensor positioners" (electromechanical actuators that move the sensors) to automate this process. However, these introduce additional moving parts, maintenance requirements, and mechanical wear and tear. Electronic guide point adjustment achieves the same result mathematically using software and wide sensors, completely removing the need for mechanical sensor chasing mechanisms.

Unlike other forms of guiding, the goal is to align the rewind roll to the position of the incoming web, ensuring a straight wound roll.

Specific reasons for this configuration include:

• Chasing Control System: Rewind guiding is fundamentally a "chasing control system" rather than a lateral control system. The rewind stand must physically move to position the winding roll directly downstream of wherever the web happens to be.
• Maintaining Relative Position: If the sensor were fixed to the ground (as it is in unwind guiding), the system would not know the relative position between the winding roll and the incoming web. By attaching the sensor to the moving stand, the sensor moves with the carriage. When the sensor detects the web edge, the controller moves the entire stand (and the attached sensor) until the sensor is re-aligned with the web, effectively "chasing" it to maintain the correct relationship.
• Roll Alignment: This setup ensures that the edge of the rewind roll is constantly aligned with the edge of the approaching web, regardless of where the web is drifting laterally.

Ideally, this sensor should be located just ahead of the last fixed idler in the machine and as close to the winder as possible to minimize instability caused by the mechanical arm's stiffness.

Intermediate Guides (Displacement & Steering Guides)

For web guides located within the machine process, the sensor must be placed in the exit span (the web span immediately following the guide roller).

• The "1/3rd Rule": The sensor should be located in the upper 1/3rd (or at least the first half) of the exit span.
• Avoid Delays: Placing the sensor too far downstream or in the next span creates time phase lag (delay). This causes the guide to continue moving even after the error is corrected, leading to system instability and oscillation.
• Steering Guides: The sensor should be placed as close as possible to the exit roller within the exit span.

Terminal Guides (Unwind & Rewind)

Because terminal guides move the entire roll stand, the sensor mounting acts differently:

• Unwind Guides: The sensor must be fixed to the machine frame (it does not move with the stand). It should be placed immediately downstream of the last shifting idler on the unwind stand.
• Rewind Guides: The sensor must be attached to the moving rewind stand so it moves with the carriage (chasing the web). It should sense the web position just ahead of the last fixed idler using a mechanical arm connected to the rewind stand. Ideally, this is as close to the winder as possible to minimize instability caused by mechanical arm stiffness.

Plane Change Considerations

If the motion of the web guide causes the web plane to twist or shift significantly (common in line guiding), it can cause focus issues for optical sensors. In these cases, a backup roller or dead bar should be installed, and the sensor should be mounted to look at the web directly over this stabilizer to maintain a constant focal distance.