PETpla.net Insider 11+12 / 2017

MAINTENANCE PET planet Insider Vol. 18 No. 11+12/17 www.petpla.net 36 PET preform mould cleaning and maintenance with dry ice Smart, smooth, speedy and safe by Gabriele Kosmehl Preform mould cleaning is an important part of the produc- tion process in order to maintain the quality of the moulded parts and the service life of the moulds. There are various methods on the market, often including a combination of chemicals/solvents, mechanical means and/or ultra- sonic baths. Dry ice cleaning is another one which stands out for various reasons, claims provider Cold Jet. PETplanet visited the company’s German headquarters and technology centre in Weinsheim to find out why. Usually it is on a Friday that the injection moulding systems fall silent to allow the cavities to be given a thor- ough cleaning. In the preform moulds, it is at the taper where deposits tend to build up due to the emission of plastic. The air vents at the neck ring and the air holes are other typical places where dust and debris are deposited. The greater the increase in cycle times, the quicker the impuri- ties build up. If not removed promptly, they lead to blemishes and unwanted flashes on the final product, creat- ing more rejects and contributing to a shortened lifespan for the tool. Previously, workers sometimes undertook the painstaking manual task of cleaning the system cavity by cavity; today the dry ice cleaning procedure offers a much quicker, cleaner and gentler method. “I’ve seen it myself how sometimes two men in the com- pany would set about cleaning out the system using cloths and cotton buds,” remembers Dietmar Juchmes, General Manager Europe. “Where previously a 72 cavity preform mould would be cleaned manually in 2-3 hours, today this is possible with our system in three quarters of an hour or less – and with significantly better results.” Key Account Manager Europe Steffen Kalisch explains why: “The Cold Jet procedure is efficient because places on the tool that are hard to access manually are also reached very effectively. Cleaning is also contactless. Manual process, as happens for example with a clean- ing cloth, always affects the material surface. Our procedure is gentle on the material and after cleaning, the system is ready for use again right from the very first shot.” Cleaning with pressurised dry ice uses rice grain sized 3mm dry ice particles that are blasted onto the tool, which does not need to be dis- mantled beforehand. The combina- tion of dry ice blast cleaning’s kinetic energy and thermal effects breaks the connection between dirt and the surface, lifting away contaminants. Because the dry ice, which is nothing but CO 2 at a temperature of minus 78.3°C, sublimates on contact back into CO 2 gas, there is no run off, rins- ing or drying of any liquids required. There is likewise no secondary waste to be disposed of, so the procedure’s neutral CO 2 footprint is a winner from an ecological point of view too. As regards employee safety, there are further positives for the odour- less environmentally friendly dry ice procedure. There are no toxic clean- Cold Jet Aero 80FP PET mould cleaning system with Tight Access applicator and nozzle 312v2 Dietmar Juchmes, General Manager Europe Cold Jet, Christiane Rach, Marketing Manager Germany Cold Jet, Gabriele Kosmehl, PETplanet, Steffen Kalisch, Key Account Manager Europe Cold Jet (from left)