Ripping a length of Clingfilm from the roll in the kitchen to wrap sandwiches for my daughter’s lunch the other day made me think of some of the issues I have encountered working on projects involving winding and rewinding machines. The very fact that Clingfilm is so stretchy indicates just one of the problems to be overcome.

Handling reels of material is common to a diverse range of processes, from newsprint and toilet rolls, sheet steel and wire to Bacofoil and wallpaper. The applications are myriad and the need for control key.

In any production system there is going to be a need for different types of winding and rewinding depending on the product being made and the materials that go into it. It might be something relatively straightforward yet delicate like perforated toilet tissue or more complex such as labels, involving silicon substrates, gluing, paper, slitting and printing.

This in turn will determine whether and in what combinations the winding is what we call Open or Closed Loop. It is a complex subject and engineers spend years getting really good at it so for the moment I am going to focus on Open Loop. I will talk about Closed Loop in another blog.

In Open Loop systems we are looking at relatively straightforward situations where production parameters vary little. In my experience with most surface winder installations, the dominant feature is in striking the right balance between the amount of torque required to start the rotation and the amount to pull the material off the roll without tearing or deforming it.  This is why Open Loop is most often used with stronger materials such as print, cable or sheet metal. There is little that is changing once the process is initiated so little need for feedback and complex controls.

There is a certain satisfaction in looking at everyday products and understanding the complex engineering processes involved in producing that innocuous roll of Clingfilm.

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