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Web guide with a edge sensor

Edge Guiding Systems

Precision Web Alignment. No Recalibration. No Mechanical Adjustments.

Edge guiding is the process of automatically positioning a flexible web (material) by tracking one of its edges as it moves through a machine. Unlike traditional systems that require operators to physically move sensors whenever the web width changes, Roll-2-Roll Technologies uses wide sensors. This allows operators to adjust the "guide point" electronically via a touchscreen, eliminating mechanical downtime and operator error. Our technology is material agnostic, meaning it detects clear film, opaque materials, and porous nonwovens without requiring sensor recalibration.

The Challenge: The "Old Way" of Edge Guiding

For decades, single-edge guiding has been the standard for web alignment. However, conventional systems introduce significant downtime and risk during product changeovers:

  • Manual Sensor Repositioning: When the web width changes, the sensor must be physically moved to the new edge location. This manual adjustment is prone to operator error, leading to misalignment and waste.
  • The "Blind" Spot: Narrow sensors (fork-style) have a limited viewing range. If the web wanders outside this small window, the system loses the web entirely, causing machine stops or errors.
  • Material Sensitivity: Traditional ultrasonic or infrared sensors struggle with changes in material opacity or porosity (e.g., clear films or nonwovens), often requiring recalibration or entirely different sensors for different jobs.
  • Temperature Drift: Conventional sensors are affected by ambient temperature changes, degrading accuracy throughout shifts.

The Solution: The Roll-2-Roll "Simplicity" Way

We utilize advanced Light Scattering Technology and wide-area sensing to solve the fundamental flaws of legacy edge guides.

Why Roll-2-Roll Edge Guiding is Different

  • Electronic Guide Point Adjustment: Instead of climbing into the machine to move a sensor, operators simply adjust the "guide point" on the controller touchscreen. The sensor stays fixed, but the system tracks the new edge position mathematically. This reduces operator safety concerns, and any possible error for manual sensor repositioning. 
  • One Sensor, Any Material: Our sensors act like a 1-dimensional camera. Whether you are running battery electrode foil, clear optical film, or porous nonwovens, the sensor detects the edge without calibration.
  • Wider Sensing Window: With sensing windows ranging from 48mm to 960mm, our sensors capture significant web width variations without needing mechanical chasing or positioners.
  • Temperature Immune: Fiber-optic technology is unaffected by ambient temperature changes, maintaining accuracy throughout shifts.
  • No Setup: No setup, no specialist required.

Roll-2-Roll vs. Legacy Systems

FeatureLegacy SystemsRoll-2-Roll Technologies
Width ChangeoversManual sensor movement requiredInstant electronic adjustment
Material ChangesRecalibration often requiredNo calibration needed
Porous/Mesh WebsOften fails or requires speciality sensorsWorks natively (Material Agnostic)
Calibration TimeMinutes (removing and fully covering the sensor)None (No-setup)
Temperature StabilityAffected by driftImmune to temperature changes
Sensing WindowNarrow (fork-style)Wide aperture (48-960mm)

Material Compatibility: One Sensor for Every Web

Traditional edge sensors force difficult tradeoffs: ultrasonic sensors struggle with porous nonwovens, infrared sensors cannot reliably detect clear films, and changing materials means recalibrating—or replacing—your sensor. Roll-2-Roll fiber-optic sensors eliminate these compromises.

Works on Any Material Without Adjustment

Material TypeTraditional SensorsRoll-2-Roll® Sensors
Clear filmsDifficult - requires ultrasonic sensorsDetects with IR reflection
Opaque substratesWorksWorks
Metallic foilsReflections cause errorsNo calibration needed
Porous nonwovensUltrasonic fails and Infrared is less accurateWorks identically
Mesh materialsChallengingDetects edges reliably

Handle Width Variations Instantly

With more converters adapting to short production runs, frequent width changes are the new normal. Traditional systems require manual sensor repositioning (introduces operator errors), automated sensor movement (mechanical wear and failure points), and changeover time for each width adjustment.

The Roll-2-Roll Approach: Our sensors provide sensing ranges up to 960 mm (38 in), allowing up to 38 inches of web width variation without moving the sensors. Set it once, and the sensor adapts to any width instantly—no lost time, no operator errors, no mechanical failures.

How It Works

An edge guiding system consists of four essential components working in a closed loop:

  1. The Sensor: Detects the lateral position of the web edge. We use Roll-2-Roll® Sensors (fiber-optic sensors) that are immune to environmental changes and work on any material.
  2. The Controller: The "brain" that compares the actual position to the target "guide point" and computes the necessary correction. The Roll-2-Roll® Controller SCU5 or SCU6x features a touchscreen for electronic guide point adjustment.
  3. The Actuator: The "muscle" that provides the thrust to move the mechanical structure. Available in various sizes from narrow web to heavy-duty unwind stands.
  4. The Guide Mechanism: The structure (such as a Displacement Guide or Steering Guide) that physically moves the web based on the Normal Entry Rule: A web approaching a roller will align itself perpendicular to the axis of rotation.

Engineering Note: For optimal performance, the sensor should be installed as close as possible to the exit roller of the guide span.

System Configurations

Intermediate Guide (Displacement Guide)

Best for: High-accuracy alignment inside the machine (e.g., before coating, printing, or laminating).

ComponentModelRole
MechanismOffset Pivot Guide (OPG)Imparts minimal stress on the web
SensorRoll-2-Roll® SensorsFixed position, electronic guide point
ControllerSCU6x with TouchscreenDigital control, No-setup

Applications: Coating stations, print registration, laminating nips, slitter entry

Terminal Guide Kit (Unwind/Rewind)

Best for: Managing master rolls at the entry or exit of the line.

  • Unwind Configuration: Guides the web into the machine by moving the unwind stand laterally.
  • Rewind Configuration: "Chases" the web to ensure a straight wound roll.
ComponentModelRole
ActuatorHeavy-duty electromechanicalMoves stands up to 6,700 lbs
SensorRoll-2-Roll® SensorsTracks edge at unwind/rewind
ControllerSCU6xCoordinates guide and chase modes

Applications: Unwind stands, rewind stations, turret winders

Technical Specifications (Roll-2-Roll® Sensors)

Engineered for simple integration and robust performance.

ParameterSpecificationNote
Sensing Range48 mm to 960 mmCovers wide web variations
Resolution0.0635 mmHigh precision edge detection
Linearity± 0.25 mmConsistent across full range
Update Rate50 Hz and upto 1000 HzFast response for high speeds
Supply Voltage24 VDCIndustry standard
   

Industries Using Edge Guiding

  • Battery Manufacturing — Electrode foil alignment for Li-ion cells
  • Converting & Packaging — Film and foil alignment in slitting, laminating, rewinding
  • Nonwovens & Hygiene — Diaper line web tracking on spunbond/meltblown
  • Label & Tag — Pressure-sensitive label web guiding
  • Flexible Packaging — Pouch and stand-up bag film alignment
  • Specialty Films — Optical films, barrier films, release liners
  • Metals — Copper and aluminum foil processing

ROI & Results

Reduce Waste, Improve Safety. By eliminating the need for operators to reach into machines to adjust sensors, you improve plant safety. By eliminating calibration, you reduce setup time from hours to minutes.

MetricResult
Material Waste Reduction*15-25% (typical)
Typical Payback Period< 6 months (many installations)
Setup TimeMinutes, not hours
RecalibrationZero

*Results vary by application. Figures represent typical customer-reported outcomes.

Trusted By: Industry leaders including multi-national tape manufacturing company, medical products company, Li-Ion battery manufacturing company and diaper and adult incontinence manufacturing company.

Related Solutions

 

Frequently Asked Questions

  • Manual Sensor Respositioning: If the web is guided to the centerline position using single-edge methods, the sensor must be moved for every width change, increasing setup time and complexity. 
  • Possible Operator Error: Physical repositioning relies on the operator to correctly locate the sensor relative to the machine and securely lock it in position. Mistakes here can lead to misalignment. 
  • Fork Sensor Issues: Conventional fork stype sensors could snag the web material if the sensor is not moved before the width change. And even after width change the sensor needs to be repositioned to ensure that the web is inbetween the two sensing arms. 

Legacy systems attempt to solve this with mechanical sensor positioners (moving sensor center guides or even moving a single sensor), but these introduce additional mechanical wear and tear. Roll-2-Roll® Sensors solves this with sensors and adjusting the electronic guide point using Roll-2-Roll® Controller, eliminating the need to physically move the sensor when the web width changes. 

More importantly the Roll-2-Roll® Sensors are single sided completely eliminating the possibility of snag or web threading issues during width change over. 

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. 

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.

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.

Edge guiding is a web handling technique that maintains the lateral position of a continuous web by sensing the edge position and automatically steering the web back on course. Edge guiding systems consist of three components: a sensor to detect the web edge, a controller to process the position data, and an actuator to physically move the web or guide mechanism. The web aligns according to the Normal Entry Rule—it naturally aligns perpendicular to the axis of rotation of the roller it approaches.

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