Traditional unwinding tensioners are mainly
mechanical, using physical contact to generate a friction force
to control the tension.
However, the tension keeps increasing when the unwinding diameter
is getting smaller so that frequent manual adjustment on the
tensioner is required. ETR series tensioners are able to reduce
the output tension values gradually depending on the
unwinding diameters to keep the tension constant during the
process.
Simply setting the initial tension value required and no more
adjustment is needed, which is convenient and stable to be
used.
To meet 99.99% pass rate for masks production and increase 30%
speed of producing with the precise tenison control of non-woven
fabric.
http://www.validmagnetics.com/component/jshopping/product/view/29/84.html