Effective cleaning for Multi-layer blown film die heads

Today´s more complex and larger blown film die heads are an expensive investment that requires a careful cleaning process to avoid costly damage.  SCHWING offers the perfect solution by presenting their new VACUCLEAN 1713 cleaning system for blown film die heads up to 1.60 meters in diameter.

Multilayer films are dimensionally stable, puncture-resistant and resistant to moisture, gases, heat and other external influences. For this reason, multi-layer blown film dies with 7, 9, or 11 layers of different plastics are being increasingly used.

Production suddenly face the challenge of properly cleaning the built up polymer and contaminant’s periodically in an effective way. The associated loss of production from restarting the plant can be up to 8-10 percent utilization and productivity of these capital-intensive investments. There are consequences of cleaning quality such as creating carbon deposits and poor surface smoothness in the tool itself, chemicals or by using simple burn-out oven. Here are some key points to consider when cleaning these dies:

  • The cleaning time or duration of the production loss,
  • The cleaning quality in particular without carbon residues,
  • The die head is continuously cleaned without damage or distortion to insure the lifetime of the investment is maximized,
  • Product quality and committee minimization during restart of the production plant,  
  • The cleaning intervals required,
  • The safety of cleaning with respect to freedom from distortion and thus ultimately,
  • The service life of the coating or the lifetime of the die

Most reputable manufacturers of multi-layer blown film lines recommend a (-semi-) annual cleaning of their die heads. Often, this is not followed by many customers due to the related costs and production loss.

Depending on its size and complexity, 100 to 250 man hours is required.
In addition, about two days for the disassembly, inspection and re-assembly of the nozzle is needed, since each layer of die needs to be individually cleaned, disassembled and remounted.

Apart from the known disadvantages of manual cleaning - damage caused by scratches or material distortion, low surface smoothness and other factors can influence the investment typically costings several million euros, these are significant production cost factors to consider!  

VACUCLEAN 1713 is the optimum cleaning system for complex blown film die heads.

During the thermal cleaning with the new SCHWING system VACUCLEAN 1713 the Multi-layer-blow head is introduced into the cleaning system. The VACUCLEAN 1713 cleans blown film die heads with a diameter up to 1.60 and weight up to 12.5 tons. It initially melts off the polymer and built up residue a gentle but effective way under vacuum. In a second phase, the remaining plastic adhered to the die is heated and decomposed in a fully automatic electronically controlled pyrolysis. In the third cleaning phase successive addition of oxygen ensures that no carbon residues in the die head. In this highly effective method that takes a maximum of about 30 hours, a multi-layer die may depend on the manufacturer, either mounted or dismounted easily cleaned. The system is designed to provide perfect even temperature throughout the complete area of the die head without any hotspots to avoid thermally damaging the die head.

Unlike conventional cleaning methods, cleaning large multi-layer blow head in a VACUCLEAN 1713 requires only one or two days is to be calculated for the cleaning, which significantly reduce the cost of system downtime and production loss. Smaller die heads and machine parts can even be cleaned in just one working day. This brings obvious cost savings and is a large return in investment.