Venjakob customises finishing line for Nolte Küchen

For popular German brand, Nolte Küchen, Venjakob designed and installed a system to be able to run economically in small batches and allow for up to 20 colour changes.

For 60 years, Nolte Küchen, one of Germany’s most popular kitchen brands, has been producing high-quality fitted kitchens that focus on people. For most users, a good price-to-performance ratio and design are among the decisive criteria for investing in branded kitchens.

The need for individuality is increasing and style-conscious, design-oriented consumers want an ever-greater selection of colours and combinations. In order to meet these criteria in the future, the kitchen manufacturer is continuously investing in the latest state-of-the-art technology.

Nolte Küchen tied up with Venjakob, acknowledged globally as the mechanical engineering specialist for surface processing, for a spray coating line with drying technology. The company was asked to supply a spray coating system with drying, which also works economically with small batch sizes and saves resources.

The project objectives included cost optimisation, quality aspects, reduction of throughput times, and greater flexibility in the production process.

Venjakob took over the complete implementation of the finishing line for coating and drying matt surfaces and, except for the sanding machine, all system components and the conveyor technology were designed, produced and installed by it.

The external sanding machine was integrated into the plant control system and the plant was to be designed in such a way that kitchen furniture components of the smallest sizes and up to 2,800-mm (length) and 1,300-mm (width) could be coated automatically in a continuous process.

Colour management

Nolte Küchen defined specific requirements for the performance of the system. Only water-based coatings were to be used and the challenge here was the variety of colours.

The system had to be able to run economically in small batches and allow for up to 20 colour changes. As each colour change takes time, a colour management system was used to keep set-up times as short as possible.

The coating process was carried out by four spray guns in high-performance linear mode. The gun speed was infinitely adjustable and fully automatically controlled.

A scanner in front of the spray booth determined the work piece shape, number and position and the guns were switched on and off precisely above the work piece. The scanner was able to detect each work piece separately and the measurements took place automatically.

All relevant adjustable parameters could be pre-set in any quantity at a central operating point in front of the spray booth via a touch-screen computer and called up as a spray program.

The individual programs could also be easily changed by the operator and all relevant process parameters could be stored in the system.

Drying process

Another customer requirement was short through-feed times so that the kitchen fronts were completely dry after the finishing process and the rear sides could be coated directly afterwards.

The drying process was coordinated with the manufacturer of the 2-component water-based UV coating material used. In addition, several test series were run in Venjakob’s own technical centre.

Drying was carried out with rising air temperatures. After coating, the work piece was first passed through a levelling zone for 2 minutes, followed by a flash-off channel with an air temperature of 30-35 °C.

The components were continuously conveyed on closed-belt conveyors where they passed into the jet-drying channel with a temperature of 40-50 °C.

Following drying, the coated surface was cured with UV light. The UV curing oven had its own electrical control cabinet, but was controlled via the control system of the overall production line.

A built-in real power control compensated for voltage fluctuations that occurred in overloaded or unstable power grids, ensuring consistent high-quality results.

Air supply

The required process air was supplemented by two central-supply air systems, which were project-planned by Venjakob and integrated into the overall concept.

In the area of spray coating, the supply air system worked with humidification. Before it left the unit, the supplied air was heated, cleaned and humidified to ensure optimum air quality for the best coating results.

A second supply air system without humidification supplied the areas of the sanding machine, the dust removal system and the drying section.

There was a special feature in the conveyor technology where the sanding machine that was integrated into the finishing line was to be used separately. For this purpose, a movable belt conveyor on flanged rollers was installed between the sanding and the spray coating machine.

When rolled aside, the sanding machine and the spray coating machine could be used independently, while for a combined operation involving both sanding and coating, the belt remained in line and allowed line operation.

Venjakob is represented in India by Nitshaw. For more information, write to marketing@nitshaw.com.

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