PETpla.net Insider 01+02 / 2015

INSPECTION SYSTEM 22 PET planet insider Vol. 16 No. 01+02/15 www.petpla.net Vision inspection system solutions To ensure a complete and precise inspection of their products, many producers and customers choose an inline or offline vision inspection system. But what has to be consid- ered after the decision about this investment has been made? First of all, the customer must specify the inspection requirements of his future system. What sounds obvious is often an obstacle when it comes to a cooperation. “Most customers have a clear idea of what is a good product and a bad product”, says Klaus Schönhoff, Technical Direc- tor at Intravis GmbH, producer of vision inspection systems for the plastic packaging industry. “Our task is to define it together with them. It sometimes can get challenging when a bad part is to be defined in com- parison with a reference sample. The goal is to specify valid rules that have been unambigously agreed upon and are understood by both parties. Our task is in the next step to put these rules into inspection algorithms.” Intensive consulting in advance To receive a vision inspection system that exactly meets the needed inspection requirements, an inten- sive information exchange between provider and customer is necessary, including valid reference samples. Klaus Schönhoff: “Ideally, we receive several numbered bad parts with an informative classification list of defect types as well as reference samples of exactly the same colour and size.” As a counterperformance, it is an impor- tant consultancy service of Intravis to tell the customer if a request cannot be fulfilled the intended way. If this should be the case, the team provides alternatives. Indirect measurements A good example: A producer wants the wall thickness to be inspected in a product region that cannot be pictured entirely by cam- eras. In this case it might be a pos- sible solution to measure the wall thickness in other regions of the cap or preform. As for every prod- uct the same amount of material is used, in this case the wall must be thicker in those other regions. Here it might be useful to define a thicker wall as a defect criterion. But this makes a deep knowledge about the production process on both sides inevitable – another evidence of how important an intensive commu- nication is. No difference at first view: Good parts and bad parts with different defect specifications Intravis vision systems Towards optimal inspection systems The requirements of producers in the plastic packaging industry have been increasing for years. On the one hand, thinner walls, caps, closures and bottoms lead to maximum sav- ings and sustainability. On the other hand, from the customer’s point of view, a constantly high level of material stability and product quality must be ensured. Moreover, the quality management has to be able to provide a complete documentation. Particular defect types also require a manual measurement to define the bad part range