Most high-production environments today demand winders that are designed for continuous run application while maintaining high-quality rolls. Minimal operator intervention through the use of an automatic cut & transfer feature has become the normal mode of operation.
Winders can be divided into three basic categories: Surface (or contact) winders, turret (or centre) winders and combination of surface and centre, commonly referred to as “Gap Winding”. Macro Engineering provides all of these types of winders, standard or custom-designed.
For successful results, choosing the right winder for a particular application is vital. As a supplier, we help customers to carefully select the best type of winder and options for their unique application. In this, and the next issues. We will discuss the advantages and limitations of each type of winder.
What is Surface Winding? – The windup roll is rotated by means of friction when pressure is applied from an adjacent driven drum roller. Since the surface speed of windup roll is always equal of the surface speed for the driven drum roller, tension control is simplified and less costly. For example, smaller motors can be used.
Surface winders are most appropriate for large diameter rolls and flexible films. A limitation for most surface winders is that the film can only be wound in one direction. (NOTE: Recently, Macro Engineering and another company in Germany started supplying surface winders with Reverse Winding features). The addition of the centre-assist option will render the surface winder suitable for winding tacky or slippery films with minimal tension and very soft rolls.
Features to consider when buying a surface winder:
Independent tension control between lower nip rollers and each winding drum
Full control of film tensions and speed during cut and transfer cycle
Patented automatic “Rising-Knife” cut- off
Spreader rollers mounted prior to each wind up
Automatic uploading of finished roll
Automatic positioning of shaft with new core, without operator assistance
Line speeds to 600 FPM (183 MPM)
Up to 70” (1778mm) rolls diameter
Maximum face width up to 30’ (9M)
Reverse winding option
Driven cooling rollers to cool the film evenly before wind up to eliminate post-extrusion shrinkage
Gap winding (combination of centre-driven and surface winder) to allow the winding of slippery or tacky films
Slitting assemblies for the production of edge-slit sheeting, edge-trimmed sheeting or multiple rolls from one web
“Flying-Knife” cut off for heavy or difficult-to-cut films
Second counter for cumulative index or length count
Taper tension control
Multiple empty core magazine
Stretch film modification package which includes special nip rollers to eliminate tension created by separation of tacky or blocked film
Overhead empty shaft handling
Fully automatic shaft and roll handling
Swing-out air shafts
Hydraulic unloading of finished roll for smaller face width winders
Automatic roll hardness adjustment through taper contact pressure control
Fully automatic core insertion
Comparison of Surface and Turret (Centre) Winders
Advantages of Surface vs. Centre:
Relatively simple tension control & drive systems
Easy to maintain low tension during cut & transfer cycle
Produce large diameter rolls economically
Less expensive than turret (centre) winders
Low maintenance
Simple to operate
Limitation of Surface vs. Centre:
Not recommended for rigid or slippery films
Not very suitable for all films and very high speeds
Difficult to wind very soft rolls because surface winding is based on friction between the drum and film roll, therefore there must be a sufficient amount of contact pressure on the roll (Note: This can be overcome with the use of gap winding)
