Controlling Static Electricity on Winders
Winders are one of the most important types of machinery for static control equipment. It is therefore important that as a company which specialises in static control, Fraser Anti-Static Techniques have a thorough understanding of their requirements. Neutralising static on a winder is, in itself pretty straight forward, however due to a variety of reasons, including machinery design, use and function it is often not possible to fit static control equipment in the ideal position to completely remove the static charge from the winder. A compromise position needs to be determined. The following information provides some clarity to customers as to why solutions vary and how Fraser Anti-Static Techniques approach specifying the best position possible.
There are 2 main variables:
1) The type of winder:
- Centre Winder
- Surface Winder (with lay-on roller)
- Turret Winder (non-stop winder)
2) The type of Static Eliminator Bar.
This depends on the maximum radius of the reel, the position where the Bar can be placed and the size of the charge.
NEOS - Due to their revolutonary power and intelligence these bars provide more flexible options - contact a Fraser engineer to discuss further.
3024L - if the core is 100mm to 500mm from Bar.
Ionstorm HP - if core is 150mm to 750mm from Bar.
Short range Bars can be used in some applications. Each of the above Bars will work at longer distances, but will not be as good. Generally, the closer to the object the better the performance. Judging the size of the charge comes with experience, but for very high charges - 100kV + -always use the most powerful Bar e.g. NEOS rather than 3024L.
This has a powered mandrel and is the easiest winder for static control.
It is possible to place a short range Bar, either a 1250-S, a 3014 or 3024F in position A, provided that the web is always within range. This could interfere with webbing up. Position A is not as good as position B.
In this situation Fraser Anti-Static would recomend a longer range Bar in position B. If the Ionising Bar is directed as shown by the arrow then both the inside of the film and the outside of the film will be neutralised. - this is an ideal situation which most operators understand.
In some applications, position B is not possible. In this case position C should be considered.
This image shows a 3700 Ionstorm Bar neutralising the winder on a Nilpeter printing machine. It is in position B where it neutralises the inside of the single web and the outside of the winder reel, delivering excellent performance.
In this position it does not interfere with the handling of the reel.
Surface winders have a lay-on roller (sometimes called contact roller) touching the reel which provides the winding power. The critical consideration here is that the lay-on roller will generate a lot of static charge. In most cases there is no point in neutralising the film before the lay-on roller, unless there is a local problem to overcome.
The best location for a static eliminator to effectively neutralise static on a surface winder is position A. This neutralises the charge as soon as it is generated as the film leaves the lay-on roller. On some small machinery it is possible to use a short range Bar, but in most cases the distances to be accommodated by the changing reel size require a longer range Bar.
If position A is not acceptable then position B is the next best choice. This will deliver good performance but it must be remembered that the area between A and B has not been neutralised, so if a measurement is taken of the static charge in this area it will read much higher than is often expected. This is because the freshly generated charge has not yet been neutralised by the static control Bar in position B.
Many winders have the option of reverse winding - this is shown in orange text in the sketch above. When the operator reverse winds, position B becomes the ideal position, and position A the second best. Most operators just accept this because it is not usually worth repositioning the Bars, or buying duplicate equipment for reverse winding.
Most customers want to reduce the charge to a low level where it does not cause a problem. Reducing charge to a low target is an increasing object with high quality films, such as BOPET and polyester, for technology applications. A typical target is to reduce the charge below 1000V on the winder. 1000V is a very low level for a winder and needs some thought, because the performance depends on many factors such as machine speed, type of material, humidity in the factory. We have worked with leading slitter rewinder manufacturers on this problem and a typical solution is to use Bars in both A, B and C.
Position C is a short range Bar to neutralise charge on the inside of the film, as shown in sketch above. This is not usually recommended for normal applications, but for those cases where the customer wants to reduce the charge to a very low level it can make a difference of a few % which helps achieve the low voltage target. Fraser would recomend a 3024F 50mm from the film.
The above image shows a 3700 Ionstorm Bar in position A.
This image shows a 3024L in position B
The above example shows the 3024L Bar in position A which is achieving excellent results. To further improve performance The ionising Bar is mounted in a reinforced GRP plastic channel to protect it . This is acceptable ONLY if it is a plastic channel, a metal channel (or other conductive material) would not be acceptable as it would attract the ions and so dramatically affect performance.
Turret, or non-stop, winders are the most difficult winders to neutralise because the winding reel does not stay in the same position and the whole winding mechanism rotates meaning that the static eliminators have to be a long distance from the reel. Traditionally Ionstorm or Jupiter Bars were positioned to neutralise the reel in the main winding position A and a second Bar was used to neutralise the charge at the second winding position B, just before the reel change. This solution has now evolved to the specially designed 3024 and NEOS Bars which are excellent for this application. As always when attempting to remove static from a non-stop winder, careful consideration has to be made of the movement of the reels.
Two Ionstorm Bars in traditional positions A and B on this Comexi flexo press winder.