Initial customer problem:

During the production of high-quality acoustic protection and heat protection for vehicles, carpet mats are pressed and punched out by our customer. In addition to the high-quality end product, this process also produces edge off-cut sections as waste. To recycle these edge off-cut sections and to form new mats for the production process was the goal of the project.

Solution:

The edge off-cuts are collected in large waste containers (1,200 liters) and filled via a lifting-tilting device into a muetek MRZ 1030 shredder. For optimum feeding of the edge off-cuts via the lifting-tilting device, the shredder was equipped with a special container. The edge off-cuts are crushed with a 40 mm sieve and fed via a conveyor belt to the briquetting press muetek MPP 450 S. The briquetting press MPP 450 S is used to produce highly compacted briquettes with diameters of 80 mm. The briquettes are filled via a briquette transport line without the use of additional energy exclusively by the pressure of the briquetting press in big bags. The filling volume of the big bags are about 2 cubic meters. In order to have enough time to change the big bags, we have developed a 'briquette rocker', which directs the briquettes into another big bag via a mechanical changeover.

The briquettes are then transported to the recycling plant for further processing. For further processing, the starting material must be very finely shredded. This shredding takes place in two stages: a pre-shredding with the MRZ 1030 with a 40 mm sieve and a fine shredding with a hammer mill with a 3 mm sieve. A lifting / tipping device is used to fill briquettes from the rear side into a MRZ 1030 shredder. In parallel, edge strips from another production line are filled by air transport in the front area of ​​the shredder and also shredded with a 40 mm sieve. A traffic light informs the operator what the filling level of ​​the briquettes is. Red light, the operator has to refill, because there are almost no more briquettes in the silo. Yellow light, the operator may refill, the level is about half full. Green light, the funnel of the crusher is full. Another filling of briquettes would lead to overfilling of the funnel. An operation of the lifting-tilting device is blocked if the green light is switched on. After the pre-shredding process with a 40 mm sieve, the shredded carpet residues are transported via a conveyor belt to another conveyor belt, which feeds the granules to a post-shredding mill.

Metal would damage the next mill. For this reason, there is a metal detector on the 2nd conveyor belt. Immediately, when metal is detected, the 2nd conveyor belt runs backwards and the 1st conveyor belt stops. At the same time, the slide of the pre-shredder MRZ 1030 stops, however, the rotor of the machine continues to run, so that no time is wasted when restarting, after metal has been removed. After fine grinding into a 3 mm granulate, the customer has optimal starting material to produce new base mats for the production process.

There were some challenges to overcome on the way to the overall solution. For one thing, the edge strips tend to wrap around the shredding rotor. For this reason, the cutting system has been modified and adapted accordingly. The biggest difficulty, however, was re-shredding the briquettes on the one hand (for internal purposes), but on the other hand simultaneously shredding all the edge off-cut sections. The shredding of the edge off-cut sections having priority, since a problem with the edge off-cut sections shredding would cause problems with the overall production process. This was solved by an appropriate adaptation of the chambers and a special slider control.