A new application process for polishing pastes combines the advantages of emulsions and solid compounds and results in a more cost-effective production process. A pilot system has been successfully used by Hansgrohe, the tap and shower manufacturer.

Until recently the Hansgrohe Group had used only emulsions in the automated process for polishing its brass bathroom fittings. However, the company reached the point where it was no longer possible to increase the productivity of the process. In comparison with emulsions, solid compounds produce a better surface finish, can be stored for longer periods and have much shorter processing and cleaning times. However, in the past it was not possible to make cost-effective use of pastes in the automated process.

Hansgrohe converted one of its polishing machines to the Melt process (Menzerna Liquefaction Technology) with the aim of cutting cycle times, reducing the amount of manual rework involved and giving the parts an even more brilliant finish. The Melt process has been developed by Menzerna in collaboration with SM Klebetechnik for applying solid compounds using automated polishing machines. It allows the machines to be supplied automatically with paste over long periods.

figure 1

The surface of the solid polishing compound in a 200-litre drum is melted and the compound is pumped into a dispensing head on the polishing ring via heated pipes.

© Menzerna

figure 2

The fittings are polished on a polishing wheel.

© Hansgrohe SE/ Braxart

Precise settings for paste quantities and supply intervals

The system was incorporated into an existing polishing machine at Hansgrohe in cooperation with SHL and SM Klebetechnik. Two polishing stations, which operate on a three-shift basis, are supplied from a 200-litre drum. A heated pressure plate melts the top layer of the compound in the drum. The viscous paste is then transported by a pump through a heated piping system to a dispensing head, where it is applied to the polishing ring.

The dispensing head replaces the spray gun or paste supply device and provides the polishing tool with the solid compound at pre-defined intervals. A displacement pump pushes the compound onto the polishing ring through a nozzle on the dispensing head. The feeding interval, the amount of compound and other parameters can be specified exactly via the control unit. After the first rough adjustment process, Melt led to a double-digit percentage reduction in the cycle time.

Menzerna will carry out further adjustments in collaboration with Hansgrohe to improve the cost-effectiveness of the process even further. Another advantage of the technology is that the level of contamination in the polishing cell is much lower, which significantly reduces the amount of cleaning required.