• Differential rewind core shaft from Convertech, a Double E Company
Differential Rewinding Core Shafts
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Differential Rewind Shafts

Double E's differential rewind shaft is the perfect solution for multiple slit differential rewinding applications.

  • Works in low or high tension applications.
  • Allows narrow and/or varying slit widths and yields uniformly wound rolls.
  • Slipping occurs inside the shaft so no core dust is created – contamination is minimized.
  • Rolls of varying slit widths can be wound in a single operation.
  • Loading cores and unloading wound rolls is quick and easy.
Differential Rewinding Shaft

Double E’s differential rewind shaft works like a “shaft within a shaft”. Winding cores are mechanically locked onto one or multiple friction rings, depending on core width. When the outer race is rotated against the inner race of the friction ring, the expanding balls ride up cam ramps to center and grip the core. These friction rings then consistently slip like a clutch around a central shaft, which runs at an overspeed RPM. Similar to a strip shaft, this central shaft contains air bladders and friction strips running along the shaft. Winding torque to the friction rings (and consequently to the cores and rolls) is controlled by adjusting the air pressure in the bladders. As the bladders expand, they press the friction strips out to exert force on the inner surface of the friction rings. Generally, as rolls build, air pressure is increased to deliver the proper winding torque. Because the web material may have variations within it, some rolls will slip more than others to creat uniformly wound rolls.

  • More accurate tension control for light tension applications.
  • Dynamically balanced central shaft.
  • Suitable for cardboard and all types of plastic cores.
  • Easier loading of cores and unloading of rolls.
  • Controls torque over larger overspeed ranges.
  • Springs ensure that all friction rings are engaged and gripping the cores across the full web width.
  • Engineers review each application to provide a custom engineered solution.

Double E differential rewinding shaft.

Shaft Ring Options

differential rewind shaft rings


UDNS – Uni-Directional No Spring
No spring assists in holding a core in place during loading. This ring has one working direction.


UDSS – Uni-Directional Single Spring
The spring assists in holding a core in place during loading. The springs also help assure every ring locks in place under a long core that covers multiple friction rings. This ring has one working direction.


UDDS – Uni-Directional Double Spring
The springs assist in holding a core in place during loading. They also help assure every ring locks in place under a long core that covers multiple friction rings. This ring has one working direction. This ring will provide a better gripping force than the UDSS on the core when rings are in a resting disengaged state. It is ideal when cores need to be positioned on the shaft off the winder and then the shaft is loaded.


BDNS – Bi-Directional No Spring”
No spring assists in holding a core in place during loading. This ring has two working directions, so both under-winding and over-winding can be achieved on the shaft without shaft disassembly.


One-inch wide spacer rings are also available to place between friction rings in certain applications.This option can reduce the price and weight of the shaft.

DRS-1000 Sideforce Shaft

Double E DRS-1000 sideforce differential shaft with keyway.

If you want to keep your side force DRS setup, but need a lighter shaft, our DRS-1000 is a simple light weight carbon fiber shaft with a groove for holding keyed rewind spacers.


Double E DF-500 roller chuck for slip differential winding.

Available Options

DF-500 - A torque latching chuck that can slide over a DRS-1000 with alternating spacer rings . Positively locks cores in place and allows you to run side force DRS without generating cardboard dust or heat.

The Differential Rewind Problem

All rolls of material have differences in material thickness and/or coating thickness across the width of the web. These thickness variations are present in each wrap of the roll. When a master unwind roll is slit and then re-wound, these thickness variations cause a different rewind torque requirement for each separate roll across the rewind shaft.


A "lock core" shaft can only transmit a single winding torque to all rolls, so some rolls may wind too loose and some too tight. This can cause many quality problems. Some are immediately noticeable rejects such as broken webs, roll telescoping, weaving, starring, and crushed wraps or even crushed cores. Other problems related to roll hardness are not as easily discovered when a wind is completed and can be passed along to subsequent unwind processes for other departments or even customers to discover.

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