Lighting and camera type key for Mettler Toledo vision inspection system

The CLS series comes in three machine sizes depending on the packaging being inspected for the correct best-before date, lot number and barcode such as the CLS 200 for 200x200mm size to the CLS 400 for 400x400mm sizes.

Cameras automatically adjust position to facilitate the set up for examination of products ranging from 10mm to 200mm in height.

External light​

Miles Kroner, sales manager vision inspection at Mettler Toledo also explained to FoodProductionDaily.com how factors including the amount of external light can affect the machine environment.

“We’ve ran into instances where you train in a product at three o’clock in the daytime and on the factory floor there is a nice window were you can see out into the field and you train it in and it works perfectly for two hours and then three hours later for some reason it’s not working.​

“The reason that’s happened that we’ve learnt is external light, so external light plays a key role into the functionality of the vision system so what we’ve done is really focussed in using the correct type of lighting to ensure that external light doesn’t come into play or we enclose our systems as well to prevent the external lighting.” ​

Kroner said key factors when designing a vision system included the product itself and what needs to be inspected.

“In order for these inspections to take place, we are going to have to verify the label on the top, the label on the bottom as well as the print quality on the top and the bottom, the expiration date, the lot codes as well as the seal, if there are any contaminants within the seal.”​

The technology can be connected to checkweighing systems and other product inspection equipment, allowing a reject device to remove packs identified as substandard by either machine.

Product type​

He added that the inspections were heavily dependent on the type of product and identified some production variables.

“So, if the seal, for instance, is not transparent that makes it more difficult for our software to detect the particles of food stuck in the seal. As well as for the date and lot codes, if the quality of the printer isn’t up to par then it’s going to be very difficult for our vision system to verify the date and lot codes.”​

He said the speed of the line and the rates of the product were other factors.

Camera difference​

Kroner added that the machine has line scan technology instead of progressive scan cameras.

“Line scan cameras allow us to inspect larger products with still having the same amount of resolution needed to complete the inspections.​

“A progressive scan is what we use on the day-to-day so it takes a picture and it takes it at one time and has a field of view that shapes out like a V or a cone.​

“How a line scan works it takes one row of pixels at a time and takes that image right directly after another and it stiches that image together, so this allows for a larger image.”​

CIVCore Software enables the machine to analyse high resolution images at a speed of 250 packs per minute (ppm).

Another feature is the hygienic design developed by CI Vision and sister company Garvens.

“There are rarely corners or edges where food can land on, the total base frame is made of stainless steel with rounded edges and the bottom camera has a sloped window on the top so no food can land or be stuck on it.​

“We have our top camera which is automated, everything is sealed and IP-54 rated so it’s ideal for the food industry.”​