Making minced meat of a major packing challenge

With a very hygiene-conscious national retailer as a key customer, Embutidos F. Martínez R.S.A., an important Spanish meat producer, set out to eliminate all human handling from its packing of minced meat, as well as to maximise speed and efficiency.

“The IPS offers excellent flexibility in terms of crate layout”

Three lines, with a total capacity of over 72,000 kg of packed product per shift, were required for the company's new factory, at Buñol, near Valencia. The project of designing and installing them, from insertion of the meat into trays to placing the sealed trays into pallet-ready crates, was awarded to Ishida Europe's Solutions Division.

Project management at the cutting edge

At the pre-specification stage, Ishida's food industry experts were able to add value by visioneering and brainstorming ideas and innovations with the customer, whose team also contributed their extensive experience. As the broad outlines of the solution emerged, another important area of expertise came into play: the ability to maximise synergy among the various packing line elements, which included denesting, traysealing, labelling, metal detection, seal testing, label reading and 'pick-and-place' packing into Eurocrates.

Ishida then applied a range of project management techniques and expertise to implement the programme, which included extensive liaison with the customer's suppliers of enterprise resource equipment and software, and of the upstream (mixing and portioning) equipment.

Most of the equipment supplied was Ishida-made, adding the benefits of single-source manufacture to those of single-supplier design and project management, just as the customer had stipulated.

A quality product

The meat arrives in the plant in RFID-tagged crates from the company's trusted suppliers. Each crateful is X-rayed, and any opaque material, such as bone fragments, removed. It is also tested for fat content, before being stored in the cool buffer at 1.5°C. 

Processing begins by assembling a 1,200 kg batch, selecting from crates that will give the correct overall consistency, fat content and appearance. The batch is processed into pieces no larger than 10mm diameter and thoroughly mixed, before passing through an extruder. This removes any hard particles and further reduces piece size to 3.5mm.

The extruded minced meat is then automatically cut and checkweighed, and correct portions are fed to the tray loading point.

Making the trays run on time

An Ishida tray denester separates trays and places them on the belt in a single lane. The denester uses rotating cams to separate the trays. These penetrate the space between the nested trays to a very limited extent, just enough to ease them apart. According to José Luis Temprado Pérez, the Plant Manager and a professional whose participation was key to the success of the project, "This is why the denester is so fast: earlier types engaged more closely with the trays, and were much more difficult to adjust and operate." 

In fact, the Ishida denester can run at well in excess of 120 trays per minute.

The denester tray reservoir allows stacking of nested trays to extend right up to the floor above, where topping up is automatically cued by a sensor.

The trays travel to the loading point, where the minced meat portions (usually either 400g or 1kg) are accurately dispensed into them. Co-ordination of tray and portion is achieved by means of several sensors positioned before the loading point.

Splitting the stream

To fully take advantage of the capacity of the traysealer, the pack stream is made to diverge into two lanes before entering.  If a simple 1:1 ratio is required, an arm pushes each second tray into the new lane. However, if a different ratio is needed (as for example when one of the tray-sealing heater-and-knife units is switched off), the tray sealer signals to the diverger and a second pusher arm comes into play to rebalance the stream of infeeding trays.

The (state of the) art of traysealing

The traysealer is an Ishida QX-1100, capable of speeds of up to 200 packs per minute (ppm). According to José Luis Temprado, "When our company's President, who has driven this project from the start, saw it at the IFFA 2007 exhibition in Frankfurt, he was most impressed by its high speed and the near-absence of noise that result from its extensive use of servomotors: this is a big advance on the mechanical links, cogs and chains of more conventional models."

Sensors at the QX-1100 infeed check the length of any object passing by. If it is of incorrect length (as in the case of a skewed tray or a foreign object), the belt stops, allowing the operator to straighten the tray (or remove the foreign object) and restart the belt without delay.

The precise control of temperature at the sealing units causes the film to shrink just the right amount to produce a tight and secure seal of very neat appearance.

Probing for leaks

On leaving the QX-1100, the packs are labelled. All of them pass through an automatic quality testing station that comprises a metal detector, a sealtester and a vision system.

The Ishida sealtester is able to detect a 1mm diameter hole at speeds of up to 140 packs per minute.  "This is a big safety advantage", explains José Luis Temprado.

"Pack failures do occur, though these are mainly due to problems with the trays themselves. The tray material may have grooves or other uneven points on it, and sometimes these prevent proper sealing, despite the massive pressure exerted by the sealing tool. It is an advantage for us and our customers to have such a reliable way of picking these rare problems up. One result is that in nearly a year of operation we have not had any seal-defective trays rejected by our customer."

Ensuring data integrity

The vision system checks both label positioning and orientation. It interacts with the company's MIS system to verify the information in barcodes and text, such as dates and traceability information.

Final steps

At the end of each line, the packs reach an Ishida IPS twin pick-and-place system which is capable of up to 150 packs per minute.

The IPS offers excellent flexibility in terms of crate layout:  each layer can be arranged in a different collation pattern, which provides greater stability for the usually multi-layer crates.  In addition, the machine is able to include incomplete layers, very useful when packing to a specified number of trays.

Filled crates are removed via a crate elevator for any necessary labelling and forwarded to palletising and dispatch.

Packing faster...

The customer set project objectives of 100 ppm for their 400g pack and 80ppm for their 1kg pack, higher than would have been thought achievable in the days when portions of sticky meat had to be laboriously weighed and packed by hand.

These speeds were achieved, and indeed are routinely exceeded by each of the three lines. "Much of the equipment is capable of considerably higher speeds." says José Luis Temprado, "The limiting factor is currently the rate at which the meat can be extruded."

...means packing fresher

The meat emerges from the cool buffer and it takes 15 minutes to grind and mix a whole 1200kg batch and transfer it into the hoppers of the extruders.

To get the entire batch into crates of labelled and thoroughly quality-controlled 1 kg packs then takes just 15 minutes. The product is kept rigorously at a temperature of -1°C up to the point where it is protected by a modified atmosphere (O₂ + CO₂ in a 70:30 ratio).  From then on its temperature is maintained below 4°C.

Combined with excellent logistics and thorough control of the raw materials, the result is that the product reaches Mercadona with a nine-day shelf life.  Mercadona, with its strong emphasis on hygiene and safety, withdraws the product from the shelves three days before the end date is reached.

Overall Equipment Efficiency (OEE)

Efficiency has been excellent, with the Ishida equipment attaining an OEE as high as 90%, but never below 80%. 

Team performance

José Luis Temprado was impressed with the performance of Ishida's Solutions team.

"This was a genuine partnership, from our earliest free-wheeling discussions to the specification, scoping and project management practicalities. Throughout, Ishida were ready to tailor things to exactly meet our needs. Two small examples: they altered the gas feeding and flushing functions of the traysealer to suit our requirements; likewise, they re-programmed the pick-and-place system to take advantage of the way we operate our end-of-line activities.

"Secondly, they showed persistence: if there was a problem to be cracked, the team members concerned would stay until they had solved it, through the night if necessary.

"I believe that we got good value for our project fee!"

Ishida Technical Director Adrian Sunter commented:

"We were very impressed with the knowledge and experience of the Martinez team, whose contribution to this project was absolutely essential. We learned a lot from our short time with them and as a result were able to make at least 30 improvements that are of real benefit in packing this type of product."