INDEX

 

CAUTIONS IN STORAGE OF PVC SHRINK FILM

1. Don't expose to sun or heat (> 25°C), because the material could suffer changes in dimension. Store immediately after receiving it and stay in a fresh and shade place.

2. Don't hit neither drag the rolls.

3. Preferentially keep the rolls in vertical form in order to avoid to be marked in it surface. Maintain the part that is indicated in the label up in order to protect the fold.

4. At the moment of receiving the product, verify its dimension since later refunds for this reason won't be accepted.

5. Use first the older rolls.

 


PROBLEMS IN HANDLING AND STORAGE

 

Collapse of cardboard cores: it could be due to strikes received by the roll or to contraction of the material for exposition to temperatures higher to 25° C. 

 

 

Decrease of dimension of the film or distortion of the roll: Occasioned by exposition of the material to temperature higher to 25° C.

 

 

Rolls marked by pressure against another surface: Generally it don't represent problem unless it perforate the film.

 

 

Mistreated folded zone: This generally is caused for abuse or wrong handling of the rolls, for example, dragging of rolls, or by carrying out cuts or other works on the same. Here the problem is more serious than if it is made on the lateral part of the rolls, because practically the roll is affected in all their longitude.

27/09/2005
 

CAUTIONS IN PACKING OF PRODUCTS WITH PVC SHRINK FILM

 

Placement of the product:

Of being possible and if it don't affect the presentation of the product you must place the package so that the smallest part correspond to the height of the packing, so that don't remain very wide corners, difficult to shrink. From the other two dimensions, is convenient that the part less wide coincides with the part of the seal that includes the trim, you will be wasted less material. Only if the package is too long in order to accommodate that of this way or for aesthetic reasons or of productivity the longest part will put on in the direction of the machine. Upon retiring the trim material will be made in the another side which it is the product that is packed in order to avoid ruptures of the seal for unnecessary tensions.

Looseness of the packing:

The film should not be subject to any tension to the moment of sealing because although the film is sealed and cut won't be formed a seal with the wide enough in order to give it force. The distance between the ends of the product and the bars of the sealer will be to a distance of at least half of the height of the product in order to minimize the tension. If the feeding of the product is automatic the distance between products will be enough in order to avoid this tension. The film before sealing will be all right seated on the soft rubber surface without any tension and without wrinkles.

Seal control and sealer maintenance:

In the seal operation the sealing jaws should remain close the enough time in order to form a strong seal and cool down enough before permitting that the sealer liberates the film.

The correct control of the temperature and the time of sealing also helps to avoid a fragile seals and with perforations occasioned by the evaporation of the plasticizers that it contains the film that give it elasticity and plasticity.

A seal done to the minor possible temperature has a greater force.

Generally adherence of film on the wire exists if the temperature of sealing is very low, and on the soft rubber surface if it is very high, besides shrink distortion of the seal, detachment of smoke and dilation surplus of the wire resistance that surpasses the spring.

If excessive smoke exists, diminishes the temperature, you must change the soft rubber surface and the worn-out no adherent material insulating, Align the sealer correctly and maintain clean the wire resistance, of being necessary uses a silicon spray in order to avoid adherences of the film to the wire resistance. Sometimes it is good to cover the resistance with no adherent material ribbon.

If the material makes strands to the moment of the sealed the temperature will diminish. The sealing surface will design so that it permit a quick cooling of the surface of pressure in order to avoid that the bags shrink for the excess of temperature. If this happens and is not possible correct it will straighten the bags by means of stretch before their cooling if they are going to require additional seals, this in order to avoid packages with bad presentation, mainly in bags without shrink.

Adjust the platform of load so that the seal remain halfway the product.

Maintain the springs of the wire resistance in good conditions in order to obtain a straight seal. It is necessary that upon changing the resistance of the sealer it don't remain ample so that the function of the spring is annulled.

Remember that heat and pressure are necessary. You should have the soft rubber surface in good conditions.

Lastly maintain the sealer clean. The accumulation of film residues in the wire resistance causes smoke and burnt or open seals.

Shrinking of the product:

When you shrink the material is convenient make small perforations in order to permit that the air caught inside the packing escapes slowly and is not formed a balloon. However this ballooning is useful in order to permit a more uniform shrink and in order to protect of the temperature of the oven to the product that is packed for what it is necessary adjust the amount of perforations in order to permit a flat controlled that of for being a packing with good appearance. In surfaces like glass you should have special care with this observation since the plastic tends to adhere to the glass, mainly to high temperatures and with material very plasticized, avoiding the shrink adapted of the packing.

If presents holes in the film during the shrink, increases the speed of the conveyor, diminish the temperature of the tunnel and the speed of the air, redirect the air and check the appropriate evacuation of it. The temperature of shrink of the PVC is between 110°C and 160°C.

Do the opposite if presents wrinkles in the packing.

If the product embraces almost the whole surface of the oven is necessary a circulation of air that assures the uniform heating in both faces of the packing.

Recommendations about the type of used film:

Use thin films or of low shrink if it presents problems with the force of shrink in thin packages. Realize the seal the closest possible to the package so that less film exercises force on the product. Increase the number of perforations of evacuation of air so that the film adheres to quick to the product and stop the shrink. Help it of packing assistants that avoid that the products twist.

Use high shrink films in order to avoid the excess of film in the corners of products of high profile. If it is not possible analyzes the possibility of eliminating them by means of additional sealing that improve the presentation although they will have an additional work.

Use more rigid films if you is going to use guarantee bands or packing that they require of structural force or that they maintain their form. On the contrary use flexible films in packing that require tear resistance if rigidity in the packing is not required.

For products that require that the film is in contact with foods, that they require refrigerate or for impression request the appropriate formulation.

Place the roll in the sealer appropriately. If it is not align concerning the trajectory of the packing could tangled when are pulled in order to unwrap more film or tangled the pinholers or other parts of the equipment. You should also adjust the separator so that doesn't interfere in the free pass of the film.

Sometimes the rolls seem to be broken along all their longitude. Due to the form in which the film is manufactured is not very probable that breaks of this type to the moment of their production, however, exist when the clients detect that the rolls present this break, in accordance they uncoil the film seem to don't finish the defect. This situation happens when upon manipulating the roll the operator take a sheet of the internal part of the roll and that it don't correspond to the external layer of the same, so that upon going uncoiling the film goes breaking the external layer seeming that the roll this broken in all their longitude. In this situation the operator will cut the film completely and take the correct ends of the roll in order to continue working.


Considerations relating to the equipment:

Place the equipment in a ventilated place.

Use the connection of three poles grounded.

Land correctly the machine of packing so that the metallic assembly remains connected to the ground.

Install aluminum paper to the film separator bar and connect it to the ground in order to eliminate the static.

If being necessary installs a device for eliminate static.

Verify that the adjustment of the sealing jaws of the sealer coincides with the soft rubber surface of sealing, It don't owe there be irregular establishments. Don't use sealing surfaces of several thicknesses because you won't have a uniform seal.

Verify that the switch of the wire resistance is on until the moment that it are close otherwise the wire resistance will cut the material of packing that not is in the soft rubber surface.

Use the adapted gauge in the wire resistance of the sealer.

Verify that the control of the sealer works correctly. The mechanism should suspend the current a certain time after closing the circuit, permitting the cooling of the seal before retiring the pressure of the sealing jaws.

The tunnel should be checked and cleaned periodically in order to obtain the maximum flow of air in order to transfer the heat of the air to the film quickly causing a quick formation of ballooning of the packing and a pleasant appearance to the product.

If the conveyor is metallic, verify that it don't warm excessively, because otherwise could perforate the film.

The covers in the openings of the tunnel should conserve in good conditions in order to avoid the loss of heat of the interior.

Any modification won't diminish the capacities of the equipment.

23/05/2006
 

IDENTIFICATION OF PRODUCTIONS FAILS IN PVC SHRINK FILM
(NOT AVAILABLE )
 
Last review of this page: 06/Aug/2013

buzon@empaquesplasticos.com.mx
 

 

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