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Why print inspection is a requirement for the plastic packaging industry?

Understanding the printing industry

The printing industry is estimated to be the 5th largest industry in the world with global annual sales of over $240bn Printing is a part of practically all consumer goods, from publications to product packaging and labels. Based on research conducted by the Association for Suppliers of Printing and Publishing Technologies, the total installed base of printing presses is estimated at approximately 50,000 multi color web-fed presses (publications & packaging) and 100,000 multi color sheet-fed presses.  The print inspection industry has targeted a single segment of the printing market, the packaging segment.

Packaging as the ideal entry point because of three distinct characteristics:

  • Client quality standards are extremely high. The vast bulk of printed packaging is used in the FMCG industries, where consumers associate (indeed often confuse) packaging quality with product quality. The industry is also mainly in the hands of large, commercially aware companies, which can impose stringent quality standards on all their suppliers.
  • The raw materials used in the packaging industry such as plastics or coated cardboard are significantly more expensive than the paper used in publication printing. This means that packaging printers are more acutely sensitive to wastage rates.
  • Designs are often intricate and usually small. Packaging also frequently carries product information printed in small point sizes and bar codes. Manual inspection is clearly unsuited (more-or-less useless in the case of bar codes) to such material
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Print inspection on continuous printed web – printing onto a continuous roll-fed flexible material -- has evolved from being a totally manual task only ten years ago to a fully automated operation today - this progress has been made possible by developments in computer technology. Milestones to-date include:

  • Rotating mirror viewers
  • Stroboscopic viewers
  • Camera based video viewers
  • AOI Sampling
  • AOI 100% in color

Printing is a material-intensive and relatively low-margin industry. Printers are under continuous and increasing pressure to increase productivity and improve output quality while at the same time reducing production costs. Even a small reduction in waste levels can have a significant impact on the printer’s profitability. Current solutions initially targeted customers in three distinct niches within the carton printing and packaging sector:

  • Flexible packaging for the food industry. E.g.) mars confectionery wraps.
  • Folding cartons. E.g.) tobacco cartons.
  • Pharmaceutical packaging on foils. E.g.) printed foil for contact lens blisters.

Purchasing drivers include:

  • Marketing requirements - for contract tenders.
  • The maintenance of existing printing contracts – minimizing defects in shipped products
  • The benefits of early detection of defective print in reducing waste.

Advantages of AOI in printing

The benefits that printers derive from AOI are far from unique to their industry. Nonetheless they constitute a compelling argument and are worth recapitulating in some detail. The printing process is subject to a number of faults. The most common faults are:

  • Mis-registration, where one color impression is misaligned against others.
  • Color variations where ink quality or operational conditions such as temperature or humidity changes the colors from those desired.
  • Defects, where physical incidents in the printing process such as ink shortage or excess at critical points, lead typically to streaks or blank patches. Intrusive dust particles are a common cause of defects.

Inspect print

Prior to AOI, printers had only very weak tools available to inspect print jobs while they were in process. Strobe, rotating mirrors and video monitors can all give an image of print output. Ultimately, however, they all depend on operator attention, speed and competence. Operator attention is inconsistent even under ideal conditions. It is essentially reactive, declining once the print job has started and only rising once output quality has fallen below acceptable level and requires rectification. Attention starts to decline again once the fault has been rectified. Human inspection is subject to a range of further disadvantages:

  • Inconsistent attention span. A problem compounded by the print industry’s traditional bias towards male workers.
  • Subjectivity of judgment as to what is acceptable.
  • Workplace distractions.
  • Insufficient sensitivity for process control.
  • Varying skill level from operator to operator.
  • Imprecision. The human eye is inevitably relatively insensitive in gauging variations.

Current commercial and operational trends within the printing industry all magnify the ill effects of these disadvantages on printing companies. Most are related to time or speed or to the relatively weak commercial position of the printer vis-à-vis his client.

Conclusion

To learn more access our white papers or for a free consultation, contact us now. OneBoxVision  operates globally with solution partners in North America, Europe and Asia.

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Topics: Print inspection systems Plastic film inspection