From mirrors to the internet of things
Inspection systems have been used in the printing and converting industry for decades now. We see new generations come and go. Going back to the 1940s we saw the rotating mirrors optimized by Fife Corp on roll to roll presses. Then came the strobes, followed by the passive viewing systems, then the active viewing systems and finally the 100% inspection solutions.
If we look at the milestones to-date, the progress can be seen.
- Rotating mirror viewers used from the 1930's through to the 1990's.
- Stroboscopic viewers used from the 1970's through today.
- Camera based video viewers, introduced in the 1980's.
- AOI Sampling became the buzz in the 1990's
- AOI 100% print inspection in color took off in the 2000's
- Cloud based networks using commercial scanners
So why do printers require Automated Optical Inspection (AOI) and what is the return on investment? The print inspection industry has constantly targeted a single segment of the printing market - the packaging segment. Packaging is 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.
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.
The availability of statistical information for management reports and statistical process control.
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.
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.
Viewed in terms of the impact on printers’ profitability the case is also compelling. Most printers spend about half of revenue on material. Wastage rates of 8-20% thus translate to 4-10% of revenue. With operating margins running at no more than 10% and down to 5% often enough, it can thus be seen, as wastage can absorb the equivalent of the printer’s entire profit on a job.
Segmentation to understand needs
The printing industry splits into a wide range of sectors from publications to packaging. The following describes the packaging industry. The packaging industry is commonly split into three distinct disciplines. Rarely do you see plants encompass more than one of the following products types.
- Folding carton ( Sheet and web fed)
- Flexible Packaging
- Tag & Label
However the above segmentation is not apt when determining market requirements as it does not profile the customer and needs. This can be extended to the major end market that packaging operation supplies. The following are the dominant categories.
- Pharmaceutical & Cosmetics
The sector an operation supplies may determine the driving requirements, but not the problems that the customer wants to solve. These are normally as a result of the process or technology used. One operation may use a multiple of technologies but again normally one process is preferred. These technologies are as follows.
- Gravure ( Web fed)
- Flexographic (CI and Inline )
- Offset ( Sheet and web fed )
So the following are the key conclusions:
- The market being supplied determines the driving factors and thus the requirements
- The technology being used creates the process issues that needs to be addressed so as to meet the requirements presented by the end user sector.
- The product supplied by the inspection supplier is designed to address the process issue, maybe specifically or not, but there are two benefits to describe to the printer.
Do the current systems address requirements?
The industry has matured and there are at least 5 suppliers that exceed $50 million in annual sales, yet none of these companies exchange data between each other. The issue for printers is that all of these systems are proprietary and none of the systems work together. Printers have purchased standalone print inspection solutions rather than building a quality infrastructure.
So lets understand the way forward
How can current systems be improved? Lets split the solution into the following:
- Hardware - This is the cameras, optics , lights and computers to acquire images from the printing presses. In 2017, this is all off the shelf. There is absolutely no need for large packing operations to purchase black boxes. The equipment used should be purchased no different to any other industrial IT solution. The only requirement is the ability to produce an image at the appropriate resolution so that the product can be analyzed.
- Services - This is the engineering support required for a manufacturing operation to purchase, test and integrate the hardware. This is an expertise that some larger operations may have inhouse or they can hire outside contractors while installing their vision network.
- Software - Vendors should focus on the intelligence required to analyze the images and provide real time feedback to the operators to produce quality and on schedule. The software should store results in an open industry format that enables the process engineer analyze production and the process.
OneBoxVision works with manufacturing operations to build vision infratructure while providing software solutions for 100% print inspection, color analysis, laminate inspection, coating inspection and rewind management controls. Access our vision library to learn more.