Automatic conveyor furnace cleaning system
In 2021, Pokkels developed a special automatic laser cleaning system for moving deck plates in a confectionery. In this short article, we will explain more about the steps and the solution to the customer’s challenges.
About company
The company produces confectionery flour products: waffles and cookies. Every day 2 million products are produced. To sell this volume of products, a conveyor with moving plates is used. At a certain moment, the plate opens to feed the dough and closes to bake the product. After baking, the finished product reaches the next section of the conveyor line.
During daily operation, residues of burnt dough and oil accumulate on the surface of the hotplate and lead to product defects. The factory was looking for modern ways to clean the surfaces and turned its attention to laser cleaning. However, the serial models of laser devices were not suitable for the company due to the peculiarities of production. Then Pokkels specialists suggested automating the laser cleaning process.
Previous cleaning methods
The processing of the deck plates used to be done mechanically and chemically. The process stretched over several days: first, the conveyor was stopped and the ovens needed a day to cool down completely. Then the baking molds were filled with lye and cleaned mechanically using brushes. The cleaned molds were rinsed with water. After all the procedures, the ovens needed another day to warm up.
Conveyor plates for baking confectionery products
This method of cleaning had its disadvantages:
- Conveyor idle for 3 days;
- Labor costs for mechanical cleaning;
- Difficulties with disposal of chemical solutions;
- Reduced service interval because the lye removed grease from the moving elements of the conveyor.
Pokkels work stages
1. Selection of optimal laser radiation parameters
Before starting to develop the automated system, it was necessary to do some research to determine which laser power would do a better job of cleaning. For this purpose, we used a 500 W rack and a 100 W mobile backpack.
Preliminary testing of a laser conveyor furnace cleaning
The tests were performed directly on the conveyor plates. The Pokkels specialists made sure that the power of 100 W is enough to achieve the required result. The necessary parameters of the laser radiation were selected and the type of system to be developed was determined — a coordinate system. You can find out more about the types of automation in our article.
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2. Assembling the prototype
The Pokkels team developed a test model of an automated machine. It consisted of a coordinate system that machined the surface automatically: The system moved transversely to the moving deck plate. The prototype was successfully tested at the factory.
3. Development of the installation’s final version
The prototype showed that the choice of coordinate system for laser plate cleaning was optimal, however, a refinement was required so that the automatic installation could meet the specific operating conditions.
High operating temperature. The laser unit must clean an operating, un-cooled furnace that is hotter than 60 °C. The temperature in the shop is also high enough for the plant control unit. The standard operating limit for a laser unit is 40 °C. Additional cooling sources for the rack and heads of the laser unit have been developed to ensure correct temperature operation.
Complex shape of the plate. The surface of the deck plate has a cone shape, which can not be cleaned with laser light from one position. Therefore, the automatic unit was designed with two 100 W emitters each, which irradiated from both sides, ensuring complete cleaning of all sides of the mold.
Protection of the laser optics in a confined space. The laser treatment process vaporizes the contamination. The standard solution for protecting optics from dirt particles is the Crossjet air knife protection system. It creates air streams that prevent combustion products from reaching the lens of the laser head. However, in this case this solution was not suitable, since the device was used in a confined space. For this reason, the dirt particles to be cleaned would remain in the air and the Crossjet system, by creating air currents of dirt, would only contribute to further contamination of the lens. To solve this problem, a design was developed in which the air was fed only through a compressor and captured from the side of the lens.
Summary
The company has obtained a complete system that automatically cleans the surface of the moving deck plates and has an optimum power of 200 W. The device continuously cleans the running conveyor as soon as the baked products reach the next section of the conveyor and the bottom plate is released. Not only has the customer’s plant shortened its cleaning time, it has also greatly increased its productivity. Equipment downtime has been reduced. The conveyor now requires less maintenance because the moving parts are no longer exposed to the lye that washes away the grease.
