technology | Machinery MEASUREMENT
In-line measurement cuts waste and boosts quality on medical tubing line
US-based Pleasant Precision Inc (PPI), whose products include medical tubing and other extruded products, recently took steps to reduce material waste and part rejects by installing a meas- urement system from NDC. PPI, which specialises in the
extrusion of tight tolerance medical tubing, inherited an extrusion system from a customer – bringing the company its first extrusion process. Its goal was to improve its process to allow extrusion of thermoplastic tubing for the medical device industry. The newly acquired
extrusion line included only a single-axis laser diameter gauge to measure the outer diameter (OD) of the product for quality control purposes. When extruding plastic medical tubing, the critical measurement is the inner diameter (ID). It took 1.5 hours, and
around 20 lbs (9kg) of waste material for PPI to stabilise the extrusion process, to keep the product within specifica- tion. But the process became unstable over time, and the
NDC’s Beta LaserMike system helped to cut waste and part rejects
extruded tube part would fall out of specification. After 19 months of
operation, the extruder produced more than $36,000 in scrap material that could not be fed back into the process. Other problems included: nearly 2.5m rejected parts, at a cost of more than $50,000; an internal defect rate above 22%; and, external PPM (parts per million) of nearly 75,000. After evaluating several
measurement systems, PPI selected the Beta LaserMike
measurement and control system from NDC, which comprised a DataPro 5000 process control and data management system, AccuScan 5000 Series multi-axis laser diameter and ovality gauge, and UltraScan ultrasonic wall thickness and eccentricity gauge. The UltraScan and AccuS-
can gauges, along with the DataPro controller, work together to measure and control the critical dimensional aspects of the extrusion process such as tube diameter and tube wall thickness. The UltraScan DSP signal proces- sor with ‘Snap’ technology provides automatic setup and calibration for quick and simple operation, says NDC. The integrated system uses
The system is quick and simple to operate, says NDC 52 PIPE & PROFILE EXTRUSION | July/August 2016
two closed-loop controls in the process: one for the vacuum, to accurately control tube OD; and, the second for puller
speed to accurately control tube wall thickness to maintain the set-points established for the produc- tion run. This allows PPI to set up tighter tolerances, and so raise quality. Since it was implemented,
the system has delivered a number of benefits to PPI. “Product quality is
paramount,” said Darryl Wren, senior process engineer at PPI. “The system enables us to quickly identify product issues, make immediate process adjust- ments and resume production to produce in-spec product.” As a result, he says, PPI
has reduced scrap by 98% and start-up time by 89%. At the same time, internal defect rate has been cut to 1.3%, while the company now has an external PPM of zero. ❙
www.ndc.com ❙
www.teamppi.com
www.pipeandprofile.com
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