Center the web between two edges
Quick Answer:
Seconds to minutes per width change with moving sensors. Roll-2-Roll® Sensors adjust instantly (milliseconds).
Every width change with traditional moving sensor center guides requires waiting for mechanical positioners to reposition both sensors to the new edge locations. Depending on the distance to travel and motor speed, this can take several seconds to over a minute per changeover. For converters running short production runs with 10-20 width changes per shift, this accumulated downtime can total 30+ minutes daily. Roll-2-Roll wide Roll-2-Roll® Sensors handle width changes electronically in milliseconds with zero repositioning delay.
Quick Answer:
Moving sensors need two fighting loops (guide web + chase edges). Roll-2-Roll® Sensors use one simple loop.
Traditional center guiding with mechanical sensor positioners requires two competing control loops: Loop 1 guides the web to the target centerline position, while Loop 2 continuously moves the sensors to chase the web edges as width changes. These loops must be carefully tuned to avoid fighting each other, which can cause hunting behavior and oscillation. Roll-2-Roll systems eliminate this complexity by using wide Roll-2-Roll® Sensors that see both edges without moving—only one control loop is needed to maintain centerline, simplifying commissioning and improving stability.
Quick Answer:
Fork sensors can be hit by expanding webs. Roll-2-Roll® Sensors mount outside web path - no collision risk.
Fork sensor collision occurs when the web width increases unexpectedly (due to material variation, tension changes, or process adjustments) and the expanding web physically contacts the fork-style sensor assembly. This causes web damage (scratches, contamination), sensor damage (misalignment or breakage), emergency line stops, and material waste. Roll-2-Roll® Sensors avoids this entirely by using wide one-sided sensor mounted outside the web path—even when web width increases dramatically, there is no physical sensor in the way.
Quick Answer:
Up to 1,900 mm (75 in) of width change using dual ODC 960 sensors; no fixed maximum width, with 0.127 mm resolution.
Roll-2-Roll center guiding uses one wide-range sensor, or two sensors for wider webs. With two ODC 960 sensors there is no fixed maximum web width—the mechanical spacing between the heads sets it—and the web can change width by up to 1,900 mm (75 in) without moving either sensor, while maintaining 0.127 mm resolution.
Quick Answer:
Calculate: (max width - min width) ÷ 2 + wander margin. Select next larger sensor size.
Calculate the sensor field of view needed: (1) Find total width change (max width - min width), (2) Divide by 2 (change per side), (3) Add wander delta (typically ±10-25mm safety margin), (4) Select the next larger sensor. For example, if running webs from 400-500mm with ±15mm wander: Total change = 100mm ÷ 2 = 50mm per side, plus 15mm wander = 65mm needed. Choose the ODC 96 (96mm window) as the ODC 48 would be too small.
Quick Answer:
Wide sensing range (48-960mm) eliminates mechanical sensor positioners, reducing failures and maintenance.
Roll-2-Roll® Sensors eliminate the need for mechanical sensor positioners—motorized assemblies that move sensors to chase edge positions. Traditional center guiding requires sensor positioners because narrow sensors cannot see both edges when web width changes. These positioners introduce motors, lead screws, and sliding brackets that jam, wear out, and require maintenance. Roll-2-Roll® Sensors have wide fields of view (48-960 mm) allowing them to track width variations electronically without moving parts, eliminating a major category of mechanical failures and maintenance.
Quick Answer:
No. Single wide sensors can see both edges up to their sensing range minus 20 mm (940 mm on a 960). Wider webs may need two sensors.
Not necessarily. Roll-2-Roll offers two approaches: For wide webs with significant width variation, use two sensors mounted on opposite sides. For narrow to medium webs, a single wide sensor like the ODC 480, ODC 768, or ODC 960 can see both edges simultaneously: up to 460 mm on a 480, 748 mm on a 768, or 940 mm on a 960 (sensing range minus 20 mm of edge allowance). The single-sensor approach simplifies installation (no alignment between sensors required) and works well for label converting, battery electrode, and narrow web applications.
Quick Answer:
Center guiding averages edge defects, ignores wrinkles, and ensures symmetric margins for coating/laminating.
Center guiding provides three key advantages: First, it naturally averages out edge defects and fuzzy nonwoven edges, resulting in more stable control. Second, it is immune to wrinkles—when a wrinkle narrows the web, center guiding sees the width reduction on both sides and maintains the true centerline. Third, for symmetric processes like coating or laminating, maintaining the centerline ensures equal margins on both sides. Edge guiding would require the web edge to stay perfectly straight, which is challenging with materials like nonwovens.
Quick Answer:
Center guiding maintains web centerline by detecting both edges and calculating average position.
Center guiding is a web handling technique that maintains the centerline of a moving web by detecting both edges simultaneously and calculating the average position. Unlike single-edge guiding, center guiding systems use two sensors (or one wide sensor that sees both edges) to compute the true centerline regardless of web width variations. This approach naturally filters out edge defects and wrinkles, providing more stable control than single-edge systems.
Center Guiding Systems
Center guiding is the process of aligning the centerline of a moving web to the centerline of the machine process.