PET preforms can be soiled for a number of reasons. Sometimes particles such as PET dust or foreign bodies, including splinters of wood or fragments of PET, can enter preforms during production, transportation or storage. "If foreign bodies like these are detected during preform inspection, the preform is rejected," explains Marco Böhnke, product manager at KHS Corpoplast. Although the rejection rate for soiling of this kind is usually under half a percent, even this very slight amount is soon noticeable at a high production volume. A preform may only cost a few cents but by dedusting preforms and thus preventing unnecessary rejections annual savings into five figures can be made. The mineral water bottling plant in Gerolstein in Germany has now opted for this system.
To save costs for preforms which would otherwise be lost Gerolsteiner has placed a dedusting unit from KHS upstream of its inspection system. After six months in operation Dieter Kuhl, production manager for one-way containers at the bottling plant, is very pleased with the new extra. "We're constantly working on improving the quality of our products. Further developments in inline quality control also help us here. We're one step nearer to this goal with our dedusting unit and in addition we're cutting our costs in the long term."
The principle itself sounds pretty simple; using a compressed air lance specifically inserted into each preform the compact system removes unwanted particles at a rate of up to 81,000 preforms per hour. As a result not only are considerably fewer PET preforms lost; the risk posed by contaminated preforms is minimized further in combination with an inspection unit.
"KHS preform dedusting is a prudent addition to any quality assurance setup," says Böhnke. The deduster is upstream of the stretch blow molder and compactly integrated into the machine layout. The cleaning system is supported by an effective extraction unit which reliably ejects all particles into an easy-to-clean collection vessel. The cleaning module has been designed so that it can be retrofitted for all customers with InnoPET Blomax stretch blow molders in series III and IV.