Online plastic bottle wall thickness measurement system

measures each wall independently at speed up to 120,000 bottles / hour

Online plastic bottle wall thickness measurement system

The FocalSpec Bottle Wall Thickness Measurement System is a real-time wall thickness measuring system designed specifically for plastic bottles and containers. The system is installed on an existing conveyor downstream of a blow molding machine for 100% product inspection. The system’s MCP 100 sensors read thicknesses of each container in desired locations and stores the results in csv files. The results are displayed instantly on charts providing immediate feedback information for machine operator to quickly adjust and optimize blow molder settings after changeovers and during daily production (Picture 1). The system can also be set to automatically alert operators and to reject containers that exceed specified thickness limits with an trigger output for air blast blow-off.

FocalSpec Bottle Wall Thickness Measurement System: User Interface
Picture 1: User interface

Technical Specification

Container shape: symmetrical, non-symmetrical
Container material: PET, PC, PP
Container transparency: transparent, semi-transparent
Container color: Clear, Green, Blue, Amber, other
Thickness range: 0.002 – 0.157” (0.05 – 4 mm)
Throughput: Up to 120,000 containers per hour

Principle of operation

An integrated trigger installed immediately before the system’s probes tells the system that a container is approaching the measurement station on the conveyor. The container position is tracked by the trigger and an encoder that continuously senses the speed of the conveyor. The probes are aimed to desired measurement locations, independently on one side, and each of them scan every container at a high rate resulting often in hundreds of readings from each measurement area, depending on the conveyor speed and container diameter (Picture 2). As the bottle moves through the station and the measurement is completed by all the probes, the software then instantly calculates, stores and displays minimum, maximum and average thickness values from each measurement area. The values are compared to pre-set limits and when needed, the machine operator is alerted by the stack light. As the container position is still being tracked by the system, a bad container can be rejected by an air blast blow-off nozzle located typically immediately downstream of the system.

Picture 2: Bottle Wall Thickness Measurement System utilizes Line Confocal Imaging

The system can be programmed by trained plant personnel for virtually unlimited number of different container types. The pre-set “recipe” for the desired container type is selected from the list, the probes are positioned and the system is then ready for production. The stored recipes include independent measurement location-specific parameters for thickness alarm/reject limits, measurement location, mode and probe positioning. The software enables targeting of critical areas in flat-walled and non-symmetric containers. The machine operator may also select active blow mold cavities and package type for each production run separately.

All the pertinent measurement data is stored in the database. Measurement date and time, cavity number, probe number, minimum, maximum and average thicknesses, rejection status, conveyor speed, etc. for each measurement location in every container are recorded and stored. The data is used for instant real-time and run charting on the system’s integrated touch screen monitor. The measurement data is also available for other reporting purposes whenever required at a later stage.

System highlights

100% thickness measurement without added labor for wide range of container sizes, shapes, colors and materials
Throughput capacity up to 120,000 bottles per hour
Measures each wall independently
Non-contact optical method
Adjustable measurement spot sizes and locations
Modular design
All-inclusive construction with small footprint
Automatic data collection, storage and reporting

Download Bottle wall thickness brochure  (pdf, opens in new window)

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