World first: fully automatic robotic broaching machine

The automation of production in the food industry presents manufacturers with enormous challenges, not least due to the strict standards of hygiene and the difficulties in handling products. PINTRO bv, a Belgian specialist in the design, production and supply of machinery for the food industry, developed an innovative solution. Their fully automated Pick & Skewer system for the preparation of brochettes is a world first. Stäubli TX2-60L robots with their washable and hygienic design are used for handling and accurately skewering the ingredients. 

Different varieties of meat on skewers, such as shashlik, souvlaki, kebab and satay, are all the rage with consumers. At Beltaste in Morahalom, southern Hungary, 160 employees mainly produce shish kebabs (brochettes). For experts in automation, this is a pioneer of "Food Processing 4.0," that is, fourth-generation production technology. Indeed, the company commissioned the world's first fully automated brochette machine a year and a half ago. Meanwhile, a second unit has also been installed. 

Quick preparation of brochettes

Anyone who wants to follow the operation of the fully automatic Pick & Skewer system with the naked eye must be 100% focused. After all, the production process runs at extremely high speed. All ingredients are fed on two conveyor belts in the central point of the production line: the breaded, raw or marinated meat on one side, onions, peppers, cherry tomatoes or whatever else the recipe calls for on the other. On the side of the system are the mechanisms in which the ingredients are separated and held ready to stick horizontally on the skewers. The Stäubli robots must "pick" the ingredients and ensure that the skewer pierces them exactly in the middle. The finished brochettes are then transported to the packaging station. The Beltaste system produces between 1,000 and 1,200 shish kebabs (brochettes) per hour without human intervention - each one top quality. It was precisely the level of performance that prompted Beltaste's senior management to invest in the world's first Pick & Skewer system. Leon Muyshondt, Chief Technology Officer at Beltaste in Morahalom explains: "We spent a very long time looking for a solution that would increase productivity while improving quality. No solution met our needs. When we saw the Pick & Skewer, we were immediately convinced. We believed in the concept and had confidence in the developer and manufacturer."

Five robots process 15,000 different ingredients per hour

The system was developed by the Belgian company PINTRO. The name is a simplified form of the English 'pin through'. Since 2007, this subsidiary of SMO bv, specialized in custom machine construction, produces machines for the manual or semi-automatic production of brochettes. With the Pick & Skewer, a great leap forward was made to the fully automatic preparation of brochettes - and that on a large scale. Depending on the desired output, all ingredients are picked by a minimum of two and a maximum of five robots and kept ready to be skewered. Beltaste opted for the version with five high-quality Stäubli TX2-60L HE robots. Because one six-axis robot can pick and skewer up to 3,000 individual ingredients per hour, the system achieves a maximum throughput of 15,000 ingredients. Taking into account 10 pieces per skewer, this amounts to 1,500 brochettes per hour.    

Flexible change of ingredients

The robots are guided by vision systems and operate based on recipes stored in the control system. In doing so, they are not only fast, but also versatile. "We usually change recipes every 16 to 20 hours. If this involves changing grippers, it takes only five minutes thanks to the quick-change systems," says Muyshondt. The PINTRO engineers invested a lot of know-how in the development of the grippers. The result is a combination of mechanical and vacuum grippers that grabs several ingredients at once and then pierces them with extreme precision - otherwise the high level of performance could not be achieved. Each robot produces a brochette in a matter of seconds. The exact position of each individual ingredient is controlled by image processing systems. Pieter Weyens, head of PINTRO: "The ceiling-mounted Stäubli robots grip and position each ingredient with an accuracy of ± 0.1 mm. Precise positioning and alignment are not the only criteria important in this installation. After all, the brochettes must look as if they were handmade."

Choosing a robot: hygiene as a decisive aspect

In addition to speed and precision, hygiene and cleanability also played an important role in the choice of the robot. The cleaning procedures are tough, as Muyshondt describes: "Twice a day we run an automatic cleaning and disinfection cycle of the tools, which takes one and a half minutes each time. After each shift, the equipment is thoroughly cleaned and disinfected: first, foam is applied, then it is hosed down with hot water from a cleaning lance with a pressure of 40 bar. The robots are also cleaned this way each time." The HE version of the six-axis Stäubli TX2 robot - a variant specifically for humid environments - is waterproof and thus ideally suited for such an application. It is fully encapsulated and endures the entire cleaning cycle without any functional limitations. Even frequent and intensive cleaning processes, such as in the pharmaceutical and food industries, do not shorten its lifespan. Moreover, HE robots are designed to function even in sensitive environments. Their washable, hygienic design is considered unique. The robots used in the Pick & Skewer system are lubricated with food grade NSF H1 oil. "The robots are heavily loaded because they make a lot of fast and delicate movements. So the lubricant has to be efficient while meeting the requirements of the food processing industry," Muyshondt points out. The H1 oil, developed by Stäubli in cooperation with an established lubricant manufacturer, meets these criteria perfectly.

Simple programming, even easier to use

Coordinating image processing and robot movements at this speed and with such high accuracy clearly also places demands on the robot controller. In this area, too, the machines score high: Stäubli CS9 controllers are known for their strong performance and excellent connectivity. Another advantage is their simplicity of programming. Users of the Pick & Skewer have it even easier, according to Muyshondt: "The worker simply selects a recipe, loads the ingredients and presses the start button - done!" While the preparation of the brochette is running, ingredients can be added. And the image processing systems also oversee quality control of each individual skewer.

A concept with many advantages

With the Pick & Skewer, PINTRO has developed a global first for the food processing industry, overcoming many obstacles - such as with the design of grippers that pick pieces of onion and cherry tomatoes and stick them on skewers at a speed that is almost impossible for the human eye to follow. Because the system processes raw meat, the entire process must be carried out under the strictest hygienic conditions. Fortunately, this is no problem at all for Stäubli's HE robots. This concept offers clear advantages. Muyshondt is enthusiastic: "The quality of the kebab skewers is consistently high. The ingredients are skewered precisely and we have a free choice of ingredients. The cleaning and disinfection times are extremely short and the robots can be cleaned at the same time. This is the future of kebabs (brochettes) preparation." Due to the great success of this first Pick & Skewer line, Beltaste recently commissioned a second system at its plant in Hungary.