Special edition: product inspection

Detection of density: The metal can files

Picture: ©iStock

Metal cans are more challenging to inspect than low-density containers because the packaging presents a higher density to the x-rays.

Packaging features can create areas which are difficult to inspect such as the ribbed side walls and tiered base. 

For example, contaminants can be concealed within inner beading and line speeds – which are notoriously fast in the food and beverage sector – can make accurate detection difficult.

Food and beverage cans are produced with, on average, over 50% recycled materials.

What is an acceptable product?

As regulations such as the Food Safety Modernisation Act (FSMA) come into effect manufacturers must ensure they have a robust product inspection programme.

This ensures compliance and reduces the possibility of costly product recalls and risks associated to consumers.

High speed lines require high resolution images to be captured and reject devices need to be capable of removing packages suspected of contamination from the production and be ready for the next can on the line.

X-ray machines available today are designed to inspect and reject cans with high accuracy up to a speed of 1,800ppm, meaning the system will not cause a bottleneck on the line.

The challenge is having a repeatable product presented to the x-ray machine every time.

Templates of products that fall within acceptable parameters are learned by the system and if there is a product that’s inconsistent in presentation it is immediately rejected. When packaging imperfections or problems with the containers themselves are present, false rejects can occur.

Customers can use x-ray machines as a root cause analysis tool if they are experiencing a high number of false rejects to improve manufacturing processes earlier on in the line.

Canning systems can use single and split beam technology. Horizontal split beam systems can be preferable as they increase the probability of detecting small contaminants on the base or side walls of the can.

Reject systems that work with the detectors are capable of removing products from the line suspected of contamination without any reduction in throughput.

X-ray equipment installation

Systems can fit over an existing line and are adaptable to suit individual requirements.

This keeps downtime associated with integration to a minimum and ensures customers can experience the benefits of x-ray product inspection without major disruption to production schedules.

Multiple generator and diode options are available to suit every application and ensure reliable detection sensitivity.

X-ray systems can operate with low level power, reducing overall power consumption by up to five times in some instances, contributing to lower running costs.

X-ray systems are also able to perform other quality control checks simultaneously.

Fill levels, for example, can be monitored to ensure there are no under-filled products reaching the retail supply chain. Overfills can also be detected, which leads to savings for manufacturers in terms of product giveaway.

Packaging defects, such as dents, can be identified and products removed immediately.

These additional quality control checks add value in terms of customer satisfaction and potential cost savings.

  • Paul King, head of sales of Mettler-Toledo Safeline X-ray is based in Royston, UK. He is responsible for sales activities in X-ray technology for product inspection with more than 25 years of experience in the food and pharmaceutical inspection industries.

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