The consistency and quality of laser generated perforations used on product packaging has a direct influence on the shelf life and ultimately, the value of the produce within the pack. It is essential therefore, that the systems used to produce these micro-sized apertures incorporate reliable methods of controlling and guaranteeing the size and shape of the holes being produced.
When a laser pulse hits fast-moving material the quality of the resultant hole may not be quite as required. If web speed exceeds certain values, the holes become visibly oval and there may also be insufficient energy available within the pulse to completely perforate the material. In some cases, material produced at high speed is not of the accuracy required to allow the specified air exchange for the packaging and can therefore be deemed unusable. The traditional method used to overcome this issue was to reduce the web speed, but this in turn results in higher production costs.
The introduction of Rofin's WMC system dramatically cut material waste and also allowed previously unattainable web speeds to be achieved, in some cases quadrupling previous performance. Web Movement Compensation (WMC) technology also allows satisfactory perforation of materials that previously could not have been processed at profitable rates, such as thick films (>100µm) or films comprising of sophisticated material combinations.
Vision system monitors perforation quality and consistency
Rofin’s high speed StarPack Web Direction System comprises of a 600W CO2 laser, with up to 4 individual W~MC heads. In this configuration, web widths of up to 1.8m can be accommodated with production speeds in excess of 350m per minute.
The addition of in process vision inspection to the system further enhances quality control and enables measurement data to be recorded and analysed. The vision system captures images on-the-fly and checks hole diameter and percentage roundness. The system can be set to alarm if a pre-set number of holes are out of specification, thus ensuring that the perforated film which is delivered to the end user meets the exacting standards required to maintain product freshness and shelf life.
Rofin laser perforation systems have been developed by product designers with over 30 years of experience in processing materials on web systems. Rofin use their own laser sources as a starting point and match them with optics, scanner heads, machines and software to provide the optimum technical solution. A graphical user interface allows user-friendly control of the entire system including previews of possible perforation and scribing speeds.
Rofin offers a complete range of lasers including CO2, Vanadate and Fiber Lasers. Rofin also provides solutions for laser marking, cutting and welding applications.