SETTING UP THE BALE WRAPPER

Setting up a wrapper to ensure proper film application is quite simple. However if done wrong, all the good work and expense of growing the grass, baling and applying Silawrap can go to waste. In fact there is a risk of bales splitting. Setting the film dispenser height, applying the correct number of film
turns and possibly tightening the belts on the rotary table are all the adjustments that are
required. It is important to monitor the wrappers performance throughout the season.

When set up properly silage quality will improve and there may even be an opportunity to save film.
When working properly wrap will be applied to the centre of the bale. In other words the distance from the top of the film to the top of the bale is the same as the distance from the bottom of the film to the bottom of the bale. This is clearly not the case in picture 1 below.

Picture 1: Silawrap is being applied too high on the bale. A quarter of the bale has 1 layer or less after 6.5 rotations

NUMBER OF TURNS REQUIRED TO WRAP A BALE

Count the number of turns needed to cover the bale with film. Remember there is only 1 layer of film on the last part of the bale to be covered. Add 1 more turn to place 2 layers on all off the bale. This figure is multiplied by 2 for bales being wrapped with 4 layers and 3 for the increasing number of farmers wrapping with 6 layers. In years gone by 15 rotations of the turntable was enough to wrap a bale with 4 layers of film. However bales are bigger now and a minimum of 16 and in some cases 18 rotations are being applied to wrap a bale with 4 layers. The brand of film used is also important as some brands neck down more than others thus reducing film overlap and seal.

IS YOUR WRAPPER WRAPPING THE BALE EVENLY?

Place a bale on the wrapping table and apply 6 turns of Silawrap. Picture 1 shows that after 6.5 turns there are 2 layers of film on most of the bale. As this wrapper is set up, 9 rotations of the turn table are required to apply 2 layers of film to the bale.

ADJUSTING THE FILM DISPENSER HEIGHT

This setting is simple to do. It involves setting the film dispenser unit so that the film passes 2 to 3 centimetres above the cut and tie knife as shown in picture 2.

To adjust the film dispenser height place a jack under the dispenser post. Slightly loosen the bolts that attach the tower to the wrapper frame. Adjust the jack to lower or raise the tower slowly. Gentle rocking may be required. Tighten the bolts and check film height once more as per picture 2. Wrap a bale with 6 or 7 turns to see how the wrapping pattern has improved.

Picture 2: Film clearance on the cut and tie.

BELT TENSION

On most wrappers the bale sits on 3 or 4 belts. These belts turn the bale to get the proper film overlap during the wrapping process. In other words the outer layer of film should cover half of the previous layer. If the belts are loose the over lap is greater than needed and the bale requires more turntable rotations to be wrapped with 4 or 6 layers. In some instances, when the belts are loose, only 2 or 3 layers of film are applied to parts of the bale after 16 rotations. As a result the risk of bale splitting is high and silage quality is reduced. Belt tension can be changed by loosening the bearing pillow blocks on the idle roller see picture 3. Push the roller out and tighten. This will rise up the bale on the turntable. It will also prevent the belt slipping when very heavy or light bales are being wrapped. Check film overlap after this adjustment. There is a higher risk of bales falling of the wrapping table after tightening the belts. In this case wrapping speed may have to be reduced slightly.

Picture 3: The bearing pillow block on the idle roller	Picture 4: Silawrap is applied evenly to the bale after 6.5 turns. Compare this to pic1

When you have completed your adjustments it is important to regularly check that bales are being wrapped properly throughout the season.

The wrapper is now set up and ready to go. In picture 4 the wrap is applied more evenly to the bale. The ones in the picture indicate 1 layer of film. Note these are near the box at the front of the bale as well as at the back. There were 2 layers of film applied to the bale after 8 turns. Before the adjustment 9 turns were required. This amounts to a film saving of over 10%.

HOW MANY TURNS ARE REQUIRED TO APPLY 6 LAYERS?

An increasing number of farmers are now wrapping with 6 layers. This increases the bale seal preventing oxygen from entering the bale. In Sweden farmers wrap with as many as 10 layers. In the example above a bale would require 24 rotations of the wrapper. Some farmers apply 20 or 22 rotations to the bale. It is our view that this is a waste of money as part of the bale still has only 4 layers of film. Gas will escape and oxygen will gain entry more easily where there are 4 layers.

Picture 5: The bale was wrapped with 4 layers, 16 rotations of black film and 6 rotations of green film. 2 more rotations are required to apply 6 layers all over, otherwise the green film is wasted.