Deutsche Bahn field test: faster bonded-joint corrosion repair with MONTI surface preparation

In a November 2011 field test on an ICE 3 trainset, Deutsche Bahn evaluated a faster corrosion-protection repair for bonded and sealed joints. MONTI’s rotating stainless-steel bristle tools were used to prepare the bonding surfaces — roughening the substrate to a blast-like profile and enabling a shorter repair-coating cycle.

Background

Repairing a bonded joint — for example around a bonded windscreen on a rail vehicle — requires the substrate to be fully load-bearing and free of corrosion. On coated substrates, coating damage appears over a vehicle’s service life through standing moisture (for example from leaks) or mechanical damage when a defective screen is cut out. Larger damage requires the coating to be renewed, and paint and adhesive manufacturers typically specify a cure time of at least seven days at a minimum of 20 °C before re-bonding.

On behalf of its P.TBS 1 department, Deutsche Bahn investigated a Mankiewicz coating system that internal testing suggested could cut the drying time to around 48 hours. Neutral-laboratory corrosion tests (ILF Magdeburg) confirmed that the single-coat lacquer gave corrosion protection comparable to the previous two-coat system on aluminium, and ageing/adhesion tests (including “cataplasm” ageing) showed good adhesion on aluminium. Results on steel were found not sufficient and were flagged for further investigation.

Surface preparation

The bonding and sealing surfaces were prepared with MONTI’s stainless-steel bristle tools, which roughen the surface in a manner analogous to a blasting process. The field trial found:

• The compact in-line (“stab”) bristle tool gave good access in confined joint areas, with the operating pressure limited to 5.4 bar via the supplied pressure reducer; running at higher pressure reduces belt life.
• An 11 mm stainless MBX band worked well for removing small-area coating residues, with a “half” band useful for corners.
• The wider Bristle Blaster® band (22 mm, ~6.5 bar) increased area output on larger surfaces, at some cost to flexibility.
• Where a pre-tension roller was used to raise output on larger corrosion damage, the resulting profile could become too deep for the single-coat lacquer; in those cases a light pass with 100-grit paper smoothed the profile peaks.

Reference “touch samples” of the target surface finish were produced by the Krefeld works and shared with the participating depots. Electric drives were noted as available but tended to overheat under sustained load, so pneumatic drive was preferred.

Outcome

The trial — carried out on an ICE 3-TK trainset at Krefeld on 15–16 November 2011, with MONTI and Mankiewicz supporting — verified the applicability of the mechanical preparation step and the faster repair-coating system on aluminium, and the findings were documented in a work instruction for roll-out. Deutsche Bahn noted that the repair lacquer studied was not suitable for steel and recommended further work for steel substrates and for bonding on GRP (glass-fibre) surfaces.

This article summarises a documented Deutsche Bahn results protocol. It describes the railway operator’s own field evaluation; MontiPower supplied the surface-preparation tooling and technical support.