Quality Control Automation Machinery Advancing

Compiled by Don Rosato

Keyword Abstract: machinery, quality control, online monitoring, moisture analyzer, Arizona Instruments, Computrac Vapor Pro, Cognex Corporation, SmartView, surface inspection system, machine vision system, AgrTopWave, PETWallplus, PET, bottle, VisyPak, Krones, Contiform blow molders

Advances in Quality Testing and Online Monitoring

Traditionally, plastic processors have relied on their material suppliers for physical property data, but the necessity for real-time, reliable test data on incoming raw material, various production stages, and on the final product has meant that more manufacturers are establishing test labs. Understanding and adjusting the manufacturing process can pay dividends in maintaining quality standards, and lessening scrap/rework. Data on many plastics physical properties that can help optimize material formulations, processes, and quality control, such as tensile, flexural, compressive, tear, and shear strength can be determined using a universal testing machine. Additionally, other testing equipment can be used to establish rheological properties, weatherability, color, and appearance as part of a complete quality program. Advances in electronics, data acquisition and analysis software have improved the performance of testing equipment, lowered equipment prices, made them easier to use and in some cases, provided for closed-loop control or automatic defect rejection.

Pellet moisture analyzers that use relative humidity sensing technology are now approved under a new standard, D7191-05 'Standard Test Method for Determination of Moisture in Plastics by Relative Humidity Sensor' adopted by ASTM last year. Arizona Instruments LLC's Computrac Vapor Pro is an example of this type of instrument, which provides fast, safe, cost effective moisture analysis. Relative humidity sensor technology has many advantages over traditional 'wet' titration methods that require broad training, costly glassware, and continuing costs for chemical reagents and disposal fees. Relative humidity sensor instruments, such as the Computrac Vapor Pro are durable enough for the production floor while sufficiently versatile for the laboratory, and require little training to use accurately so that even an inexperienced operator can produce reliable results.

Computrac Vapor Pro (Source: Arizona Instruments LLC )

To further assist in quality control related inspection tasks Cognex Corporation's 'SmartView' surface inspection system is finding increased use. A leading supplier of machine vision systems, Cognex has added a totally new inspection capability to its SmartView. A new software package, called Surface Quality Monitoring (SQM), automatically assesses the overall visual appearance of the surfaces of metals, plastics, and other materials, as they are being produced. Unlike SmartView's defect detection tools which identify and categorize discrete defects on material surfaces, SQM is used to evaluate surface qualities such as smoothness, roughness, texture and patterning to be certain that they are within acceptable limits, and alert plant operators when predetermined limits are approached so that adjustments to the process can be made. Cognex is the only supplier of surface inspection systems offering this revolutionary new capability.

Cognex's SmartView system is a state-of-the-art surface inspection system that is used to automatically detect, identify, and visualize defects. SmartView can detect and classify defects much smaller than a square millimeter in the most challenging applications at full production speeds, which enables manufacturers to both improve product quality and reduce scrap, resulting in increased profitability.

PETWallplus Improves Bottle Production Control

VisyPak, a division of Melbourne based Visy Industries, Ltd., and a market leader in the supply of clear, polyethylene terephthalate (PET) plastic bottles and PET preforms is using AgrTopWave PETWallplus with Vision to keep off-specification product out of the customer stream. The division's largest PET container plant in Kings Park produces 1.2 to 2.5 million PET beverage bottles a day (depending on the season) with blow molding machines operating at speeds of 45,000 bottles per hour. More than 60 different SKUs are made requiring frequent changeovers to produce the various bottle sizes and shapes for soft drinks, juice, water, and alcoholic beverage applications. The bottle processing speeds, volumes and varieties leave the division no room for processing error.

VisyPak Uses PETWallplus Vision in PET Bottle Production (Source: VisyPak)

Manufacturing at VisyPak is about automating wherever possible, reducing costs and adding value to the manufacturing process. VisyPak can't afford to have quality issues. The Kings Park plant installed an AgrTopWave PETWallplus with Vision process monitoring system inside each of its Krones Contiform blow molders. The PETWallplus incorporates non-contact wall thickness measurement and random defect detection in one compact unit. Most bottle defects occur in the neck or base, where shape or directional changes can create stress points reducing bottle performance. PETWallplus with Vision combines non-contact wall-thickness monitoring with high-precision camera-based inspection, using infrared light absorption techniques to measure accurately critical areas for changes in material distribution and visual defects. The monitoring system both rejects non-conforming bottles, and associates measurement data with individual molds and spindles inside the blow molder. The feedback is displayed on the PETWallplus' freestanding user interface. Continuously updated, the data are presented as easy-to-understand charts and graphs so the operator can quickly assess blow molder performance in real time and respond as needed.

PETWallplus supplies Visy with an early warning system. Before the monitoring system was installed operators often had difficulty relating cause and effect. Operators would have to resort to physical inspection of a bottle, cutting it up and examining it section by section, during which thousands of nonforming bottles might be made, then attempting to correlate action directly with the results. Use of the monitoring system has eliminated the guesswork. In less than six months of operation, the Agr system allowed Visy to significantly improve bottle performance, and also discover defects that had previously passed unnoticed.