An industry-first keeps Kraft's chocolate hearts in the right place - METTLER TOLEDO
 

An industry-first keeps Kraft's chocolate hearts in the right place

An industry-first keeps Kraft's chocolate hearts in the right place

A single X-ray detector checks seal quality as well as product size and alignment on the Marabou Noblesse line

Marabou has been the favourite of Swedish chocolate lovers since 1916. As if to prove the point, Kraft's Marabou Noblesse chocolates now come in heart shapes in sealed trays of clear plastic. But shaped chocolates sometimes bounce out of line, while stray pieces of chocolate can easily compromise the seals in the trays.

So Kraft asked Mettler-Toledo Safeline (MT) to suggest ways of monitoring product alignment and tray seals. MT adapted their InspireX R20 inspection system to create a packaging industry first – a split-beam X-ray machine that automatically checks and rejects for two entirely different production-line problems. The result is an efficient and fast-moving line that runs without the need for human inspection.

Putting an end to hit-and-miss visual checks

Kraft used to check the seals and alignments of Marabou Noblesse chocolates by eye. It was a labour-intensive and fallible process. Each plastic tray has four compartments containing a stack of seven heart-shaped chocolates, and about 400mm of seals around the tray perimeter. The task was an obvious candidate for automation.

"We called in MT because they'd already installed X-ray inspection systems on two of our production lines," says Emma Oxborn, Manufacturing Business Development Project Coordinator. "Our experience with MT had been good."
 
Customisation gives multizone inspection

MT technicians immediately saw that the problem was solvable – but not with an off-the-shelf X-ray detector. Mattias Nettrander, an MT Sales Engineer recalls asking Kraft how serious they were about solving both problems in one go.
 
"Kraft were adamant that product quality was top of their list," he says, "so we took a range of product samples to our development laboratory in Royston, Hertfordshire.
 
"It took us about two months to develop new software. Our challenge was to detect stray particles smaller than 2mm in a tray seal with rounded corners as well as variations in alignment of chocolate hearts. Since there are four compartments in each tray, we had to zone the X-ray image to examine product alignment and product mass in each of the four areas individually."

Split beam provides two tests in one

The actual X-ray inspection system was an InspireX R20. MT adapted it to fit the Kraft production-line specification.

Mattias explains: "The length of the machine had to be exactly 1325mm to fit the space left by an existing metal detector. We split the X-rays generator to give us separate X-ray beams for each of the detectors, and we redeveloped the reject mechanism so that product with poor seals went into one bin and misaligned or misshapen product went into another."

Easy to install, easy to run

Installation of the R20 in Kraft's Swedish plant was straightforward. The machine replaced the metal detector at a location towards the end of the production line, immediately before the plastic trays are inserted into their cardboard retail packaging.

"Since installing the R20, the Marabou Noblesse line runs at 55 trays a minute with minimal downtime," says Emma Oxborn. "The equipment requires no specialist operators; our regular production staff can set it up at the touch of a screen. Cleaning is very easy, and our own maintenance team can maintain it. As a result, we can run that line for 16 hours a day, five days a week. And once a week we switch production to another of the three chocolate products we make on that line."

She adds "I don't think any other X-ray detection system would have worked so well. MT offered us the best solution compared to their competitors; they were happy to adapt it to our specific needs; and their after-sales service is very good.

Would we work with MT again? Yes, they gave us two detectors instead of one. With MT equipment on our line, our customers continue to enjoy superb quality chocolate. They can tell in an instant that our hearts are in the right place."