WCA March 2012

Data processing and recording in extrusion lines

ONLINE recording of production data has always played an important role in cable production. In the past data was collected separately at every single production line. Therefore, simple plant computers were used in combination with a printer for extensively printing out the data at the end of the production process. In particular, data archiving was a major problem. Nowadays, the measuring values are recorded and stored digitally in real time. This is especially important with regard to the high capacity of the lines and the related data volume. There are two possibilities of data processing. On the one hand, production data is measured online and directly transferred to a central quality assurance system. As there is often measuring data of several production lines available to the operator, a line computer is quickly at its capacity limit. That is why measuring data is first collected and processed in processor systems such as the Sikora Ecocontrol before being transferred to a line computer. Data can be stored daily, batchwise but also reelwise. The processor systems determine trends and statistics over the entire production process and document quality characteristics of the product for defining Cp or Cpk values. In addition, they provide information on possible surface faults on the cable such as lumps and neckdowns. The online processing and recording of quality characteristics is a significant progress for the cable production compared to the past. Five years ago, a cable manufacturer could make a statement about statistical data. However, he had not received details on the single values as they were averaged. Therefore, a cable could be shown

concentric in the average value, although it was punctual eccentric. Only by means of a cut cable sample could the operator recognise that the core was eccentric in the insulation and the cable did not fulfil quality requirements. Nowadays there are solutions such as the so-called cloud diagram, which graphically present the distribution of short-term variations of the eccentricity. The information is stored and transferred to a line control via serial interfaces or simply by a USB stick. As a result, the operator and the quality management continuously have production data available for monitoring processes and improving them with the help of QS quality documentation. Ecocontrol. With the help of the cloud diagram the distribution of the short-term variations of the eccentricity are shown. The cloud consists of 5,000 dots, whereby each dot represents an actual single value of the eccentricity (value and direction). The overall distribution of the cloud diagram easily highlights the standard deviation of the eccentricity ▲ ▲ The cloud diagram is an alternative style visual view of the measurements being made at the processor system

Sikora AG – Germany Fax : +49 421 489 0090 Email : sales@sikora.net Website : www.sikora.net

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Wire & Cable ASIA – March/April 2012