Colors have a very different effect on people’s psyche and body. In addition, people have their own preferences. That is why there are paint mixing machines in about 8,000 German DIY shops and specialist shops. Controlled by computer, they are able to create interior or exterior paints in one of 40,000 possible shades by coordinated mixing ordinary white with combinations of up to 36 different color pigments. These paint-mixing machines require a lot of maintenance. After just three to five years they usually need to be replaced because a defect means that the customer would have to wait several days instead of a few minutes for their “terracotta wall paint”. However, scrapping the old system too early is not optimal either.
“Refurbishment is far more sustainable,” notes Uwe Michael Schlitt. He is Managing Director of OLDUS GmbH from Bensheim, a specialist service provider that not only maintains and repairs paint dosing systems, but also completely refurbishes them. “The objective is to restore a system’s technology to its delivery condition in order to extend the service life of the machine by at least the previous operating period,” Schlitt continues. During maintenance the machine is dismantled to its basic structure. All assemblies and components are disassembled, cleaned and reassembled into their individual parts. Wear parts are replaced.
But OLDUS does not want to stop here. In the company’s facility, there is a prototype of a system in which the color pigments are fed from bags under airtight seal, instead of filled into open containers. This makes preservatives unnecessary – as also required by the latest EU directives.
Another innovation concerns the 20 to 36 dosing pumps, which are constructed like an oversized medical syringe. Their task is to dispense a precisely measured amount of pigment into the base color. Today’s cylinders are made of steel and are particularly affected by wear, as the pigment particles are highly abrasive and act like sandpaper on the polished metal of the cylinder liners and the Teflon seals of the pump pistons. This issue is becoming even more important in newer machines, as they are designed to work faster.
“We are replacing the steel cylinders with DURAN® glass tubes from SCHOTT, whose durability clearly exceeds the typical operating time of a paint mixing machine,” reports Mr Schlitt. The glass drawn from the melt is much harder than steel, so there is hardly any abrasion. It is also exceptionally smooth on its own, meaning that unlike the steel, it does not have to be elaborately polished. During maintenance work on the machine, paint pigment residue can be easily removed with conventional cleaning agents.
“We are carrying out stress tests here with the support of a well-known paint manufacturer who will install and operate the machine,” explains the Managing Director. The glass must be able to withstand a continuous operating pressure of 2 bar and load peaks of 16 bar.
The cylinders shown above illustrate another obvious advantage of the glass: It is transparent. It is therefore possible to monitor the seals of the pistons and detect even the smallest leaks before they break through. The optical and mechanical surface properties of the glass, which are superior to steel, instantly lead to a higher durability and reliability in this application.