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1) Overwrap quality and product handling.
Various new high performance tight overwrapping films are becoming available and thus it is very important that overwrappers can hold the necessary tight mechanical and temperature
tolerances to best make use of this performance. A product's good appearance on the retail shelves more than compensates the fraction of a cent in price difference between good and poor quality film. A film that
initially yields a tight appearance can, through poor quality, relax and leave a baggy product on the shelf. It is thus important to use a film with good overwrap, does not relax, and an overwrapper that does
justice to the contemporary type of tight wrap film.
DMA: Our contemporary use of electronic control technology enables the best performance from these new films.
2) Automated vs. semi-automated :
The overwrapper /overwrapping market can be segmented into the automated and semi-automated groups. This differentiation is made on the demand of operator involvement. This is determined
by the intelligence of the input, central and output product processing systems of the overwrapper. The machine is only semi-automatic if the operator has to keep the hopper full and synchronize the end of the
current batch with the addition of blank dummy product in order to carry the good product through to the exit. This is true, not only at the end of production runs but in fact every time the machine is stopped. Also
problematic is the input supply from other automated machines that need to pause, run and stop These semi-automatic system usually have a micro switch a few product heights from the bottom of the input hopper to
turn off the drive system of the machine in advance due to momentum of the drive system. If the product should run out before stopping the machine, the continued feeding of film will cause a jam up. This part is
easily achieved but not so the clearing of the product out of the machine. If the product remains in the machine longer than during normal overwrapping, this extended exposure to the heat sealers causes damage to
heat sensitive product. It is this down side that needs to be worked around by an operator adding dummy product at the right time to clear the good product out of the machine before stopping.
An automated machine reacts automatically to the availability of product at the input and in addition clears the product through the machine at a pause or end of a run.
The trade off is thus the cost of an operator and possibly wasted product vs. the higher initial cost of a fully automated overwrapper which can easily be a two to one ratio. This choice
of a semi-automatic overwrapper is only possible for semi-automatic applications and only when other automation is not envisaged. Overwrappers running in conjunction with other machines, such as inserting machines
in production lines, need to be automatic.
DMA: Our fully automatic overwrapping machine operation is achieved by our micro processor control system any many software enhancements.
3) Feasible vs. non-feasible product size change:
The only constant in business is change! This is equally true about overwrapping product size. Just think of the new super jewel box and the Blu-Ray Disc. Overwrappers are differentiated
into two groups according to their feasibility to change size. The two factors of importance being price of change out components and the time and expertise to effect this change. The effect of size change out is
two fold:
a) Quick Size Change: This is very advantageous to the smaller business who does not wish to purchase one machine for each product size but prefers to set up one overwrapper to
sequentially run different batch sizes. This is not only a huge saving but opens up the possibility of taking in lucrative outside overwrapping work to keep a machine earning revenue more hours of the day.
b) The hard or impossible to change overwrapper. At least a costly and hard overwrapper is not a dead end road for new formats while such format changes can leave a fixed size machine
useless. It is necessary to establish these flexibility problems in advance as it can drastically influence the future value of an overwrapper.
The above parameters are important in all industries but especially in the media industry. Format changes in the near future can quickly drop a machine into redundancy. When
contemplating the purchase of an overwrapper which can not feasibly be changed, a very short amortization period is necessary to minimize exposure.
DMA: Our quick size change with minimum of change out parts is achieved by our microprocessor control system and software enhancements.
4) Reliability and maintenance:
A clear distinction should be made between the simple technical requirements of replacing general maintenance parts such as toothed belts etc. and the highly specialized maintenance:
a) Timing and other adjustments: The timing of an overwrapper can be by means of levers and cams on rotating shafts or by electronic servo control. Both are effective but adjustments are
far easier with the clearly visible indicators of the servo electronic type. The mechanical cams and levers variety, due to the force behind the motion, tend to go out of adjustment during jam ups. The electronic
servo systems exert much less pressure on the product and machine in the event of a jam up and are by virtue of being electronic also immune to these timing upsets.
b) Regular wear in the short term refers
mainly to the film cut off knife. With a dual bladed application where one blade acts on another blade (scissors action) or a cutting wheel, the wear is understandably excessive. The setting up of these dual bladed
cutting systems is usually a formidable task and needs to be repeated at regular intervals. The alternative is the film being held taught while using a single bladed cut off knife. The low wear, reliability and ease
of set up and replacement make the single cut off knife make is a winner but at a higher initial cost.
The above are serious trade offs between the use of a highly skilled technician vs. initial purchase cost.
DMA: Our overwrapper is not susceptible to such timing problems as it is microprocessor / servo based. Our cut off knife is of the long
life single bladed type and easy to replace if needed.
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