The Five Point Guide to Cost Effective Use of Wrap

1 April 2009

The Five Point Guide to Cost Effective Use of Wrap

Making best use of your resources in the coming months - your machinery, your man power and your money, will help you to maximize the value of your big bale silage, says Volac’s Jeannie Everington who urges all big bale operators to take up the following five point guide.

1, Service and set-up your wrapper

First things first; start from scratch and service your wrapper paying special attention to the pre-stretch unit (PSU), the rollers, gearing and the cut and tie mechanism. You’ll find all maintenance operations will be time well spent, so thoroughly check the following:

PSU: check all moving parts move freely and that springs have the correct tension, to prevent uneven stretching and breaking of film.

Rollers: replace worn rollers and clean off any build up of tack with a wire brush and solvent based cleaner.  Residual tack may cause aquaplaning or spiral tearing if the film slips on the roller.

Roller settings: check they are exactly parallel to the new roll of film to minimize spiral tearing and that the brake roller makes contact with the entire length of the roll, giving an even tension right across. This is particularly important with the new generation of high performance, thinner films, for example Volac Topwrap 2000. Check the bobbins holding the roll are free running: test with the roll in place too.

Gearing: check for wear and tear, including adjustment of chain driven gears and lubricate as recommended by the manufacturer.

Cut and tie mechanism: sharpen or replace the blades to prevent tearing.

Sensors: align correctly to ensure the turntable returns to its starting position at the beginning of each cycle.

Turntable: replace any worn belts as these can affect film overlap, ensure the bobbins are free and the gearing chain is clean and lubricated.

Now make a trial run with a test bale. Mount the film with the tacky side towards the bale adjusting the height of the roll holder so that the centre of the roll is in line with the centre of the bale, to ensure a consistent overlap. Wrap and  check that film overlap is 50%, and neck down and longitudinal stretch are correct for the film you are using - refer to film manufacturer’s instructions

2. Choosing film

Invest in a good quality film and net from a manufactuer or dealer who will provide an all year round reliable service. A good stretch film must maintain the following properties at all times and under all conditions: stretch, puncture resistance, tear resistance, UV stability, impermeability to air and water and an air tight seal. Cheaper films may be of variable quality depending on the type and level of the plastic resins used. 

Colour: traditionally black, but green and white are proven to keep bales cooler and promote better fermentation, reducing spoilage and improving silage quality.

Width: the wider the film the fewer the number of overlaps and the more air-tight the bale. Film is available in 500/760mm widths for standard bales, 250/360mm for small bales. Additionally the new generation pre-stretch films at 730mm and 340mm have less neck down so cover equally well.

Thickness: new generation films are as strong as, but thinner than traditional film, so the same roll weight carries a longer length of plastic enabling you to wrap more bales per roll.

Buy a film that is optimum for your own purpose, be it high quality haylage or a forage that is going to be used early in the season. Remember to always read the manufacturer’s instructions and handle film with care; damage to roll ends may lead to film breaking or spiral tearing. Store film in dark, cool conditions, in its box. Do keep a note of the film reference number, often found in the core, just in case of problems.

3, How many layers?

The answer depends on what crop you are wrapping, its dry matter (DM), bale shape and weight. A minimum of six layers should be applied to all square bales, stalky and high dry matter bales  (+40% DM), heavy chopped bales and bales to be fed to livestock sensitive to mould, for example, horses and sheep. Four layers of high quality film are sufficient for standard round bales of below 40% DM and may also be considered if the bales are not going to be stored for long. Remember that the higher the forage DM, the less water you are wrapping and the fewer bales you will have to handle. 

Wrap at the stack wherever possible to minimize risk of transport damage to the film. Bales wrapped in the field should be cartedand stacked in their final position using purpose built handlers within two hours of baling. If left longer than this, fermentation gases increase the pressure in the bale and you risk the film bursting when handled. Any film damage must be repaired with UV stabilized tape or patches to prevent ingress of air which may lead to spoilage. 

Bales must be stored away from trees, exposed areas and water courses on a level, well drained base free from any sharp stones. Stack round bales a maximum of three layers high, but keep to a single layer if they are of low dry matter material. Finally, cover with a closely woven net to prevent bird damage. Remember to leave bait boxes to stop vermin attack, fence against livestock and keep chemicals such as fertilizers, herbicides and mineral oils away from film as they accelerate its degradation.

ends

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