Materials such as paper, plastic film, foil and cloth often are produced in long, continuous sheets that are rolled up for more convenient handling and transportation.
These rolls of material vary significantly in size and weight — ranging from 2–203 inches (5–516 cm) wide and weighing as much as several tons.
The converting industry takes these continuous rolls of thin, flat materials — known as webs — threads them through processing machines (such as printing presses, laminating, coating and slitting machines) and converts or changes the web of material into an intermediate form or final product.
To avoid these problems, engineers have developed a variety of automatic web-guiding systems that assure production accuracy and reduce waste.
The system's controls must put the output signals from the sensors in to a form that can drive the actuator.
Many controls today are electronic, typically using an amplifier to convert signals from the sensor, then commanding a special servo motor incorporating a lead or ball screw for guiding actuation.
The latest web guiding systems have touch screen controls to simplify the setup procedure.