The Data Courier
Omron RFID application stories

Episode 9: Clever inspection for filling plastic containers

A major problem for beverage production lines where plastic containers, for example are filled with liquid is they have a short tact time and require a high degree of accuracy. This is made even more important by standards required in the foodstuff industry that is subject to particularly stringent levels of product control (e.g., HACCP).

In many companies the process of filling control is performed by measuring the weight of the plastic container once in the empty state and then again after the filling has been completed. The difference is then calculated to confirm that the weight agrees with the specified value. Data must be exchanged however with the host computer at each measurement, necessitating a complicated system configuration. If as a result of the inspection the filling weight is found to disagree with the specified value correction is therefore necessary and in this arrangement is cumbersome and prone to error. A high-speed way of performing the necessary sorting control quickly and simply, without sacrificing reliability is therefore required.

The Omron solution is to mount ID tags to the jigs holding the products or if the machine has round jigs then they can be fixed to the bottom with the Antenna installed underneath to ensure access even if the jigs turn around. As before the weight of each container in the empty state is measured but now the data is sent to the ID tag. The filling machine number is also written to the ID tag to distinguish it from other machines at subsequent processes. Next the weight of the container is measured again after the filling is completed and the total written to the ID tag. When the container is in the weight inspection process, the empty-state weight and total weight from the ID tag is compared and the difference checked at the host system. At this point, if the difference disagrees with the specified value the item can be sent to the correction process while simultaneously storing the filling machine number in the ID tag.

The system does not impose a burden on the host with each measurement and so a quality control system that checks every item can be created, replacing the spot-check systems used by the old methods. Handling the filling machine number and filling weight together enables inconsistencies between machines to be analysed and corrected or modified. The use of ID tags allows information to be easily distributed and so enables the system to be changed simply when new products are introduced and consequently less investment is required.

The salient products used in the process is the high-speed RFID system that allows 128 bytes of information to be exchanged in 14 ms and 8 digits of weight information to be exchanged in only 5 ms. The data carriers are equipped with Fe-RAM providing frequent access (reading/writing) eliminating the worry about the service life. The tags are designed to be resistant to water, chemicals, vibrations, shocks and noise, making for stable operation in the severest environment of foodstuff production lines.

Micromech is the systems integrator for Omron RFID systems, if you wish to find out more contact Stirling Morley on 01376 333311 or stirling@micromech.co.uk

‘Micromech, keeping track with Omron’