Extrusion International 2-2019

37 Extrusion International 2/2019 Similar approaches generate quality improvements in pipe extrusion. At the beginning of the process, the ec- centricity of the pipe must be brought under control, then the wall thickness and finally outer diameter as quickly as possible. The optimization of the wall thickness and the monitoring of the outside diameter is also ensured by the combined and cost-effective ultrasonic and laser measurement technology from Zumbach. Accurate process monitoring and quality control during cable and pipe extrusion In the extrusion of cables or pipe jack- ets, UMAC ® ultrasonic measurement ensures early notification of product centraliza-tion and achieved Wall thickness. UMAC ® measures and con- trols parameters such as eccentricity and wall thickness for up to 5 layers of materials at a maximum of 8 indi- vidual measuring points around the circumference. Additional installed ODAC ® or MSD ® diameter measuring heads benefit by checking the dia- meter and ovality. Using these tech- nologies, allows the manufacturer to closely monitor the extrusion process- es and thus continuously maintain the quality requirements. Dual Loop Strategy maximizes quality on extrusion lines Control solutions such as Zumbach’s dual-loop method, as example, takes into account the product properties in both the hot and cold conditions. The resultant reported data is determined from a combination of the diameter measurement using ODAC laser mea- suring heads and UMAC ultrasonic ec- centricity and wall thickness scanners. Wherever several ZUMBACH systems are used in combination, remarkable successes can be achieved in DLP mea- surement and control. Considerable thought should always be given to investing in several high precision and reliable control tech- nologies within the extrusion line. Af- ter all, global material costs are rising just as fast as quality requirements. Whether it is quality improvement for very precise cables or further material savings for commodity tubing – with the ZUMBACH hot end dual loop control strategy, the extrusion can be monitored and controlled even more precisely and quickly. The cost-effective process exploits the benefits of ultrasonic measure- ment and perfects it in combination with laser scanner technologies. The intelligent solution offered by the ZUMBACH control strategy makes al- lowance for the product’s properties at the hot and cold ends of the line. It utilises data from the diameter mea- surement, determined from the ultra- sonic eccentricity and wall thickness scanner UMAC ® . These data mea- surements are automatically adjusted based on the data from the ODAC ® laser diameter scanner at the end of the line and evaluated. This creates a very fast control feedback loop (due to the short distance from the point of change to the point of measurement) while still basing the control decisions on the final diameter measurements. Using this dual loop, transient devia- tions canbeminimised, in turn leading to a significant reduction in standard deviation and ultimately an increase in the process capability index (CPK). ZUMBACH Electronic AG Postfach, CH-2552 Orpund, Switzerland www.zumbach.com Dual Loop configuration with UMAC ® at the hot end, and ODAC ® at the cold Customer specific solution with ODAC ® and UMAC ® gauges in an extrusion line for products up to 500mmOD