UHS coatings for hydraulic pumps and motors

UHS coatings for hydraulic pumps and motors at Linde Hydraulics in Aschaffenburg:

In Aschaffenburg, Linde Hydraulics GmbH & Co.KG established a completely new production plant. The plant consists of production and assembly halls encompassing approximately 22,000 m². The producer of drive systems supplies manufacturers of construction and agricultural machinery as well as transport vehicles across the globe. The hydraulic elements feature dimensions of up to 1.3 X 0.6 X 0.6 m and weigh up to 350 kg.

As substrates, the company primarily uses cast iron but also plastics, non-ferrous metals and pre-coated parts. Since the parts are highly contaminated with oil and grease, Linde chose a 9-zone pretreatment with pre and post-degreasing, the application of a conversion coating and a no-rinse passivation with the corresponding rinsing processes.

In order to meet the corrosion protection requirements of currently 480 hours and also to take into account the VOC directive, we presented a UHS system consisting of UR1937 (primer), UR1025 (top coat – satin gloss) and UR1409 (top coat – glossy) with a solids content of 75 – 80 % (in mixture). Only one curing agent is required for all systems.

The main colour shades are RAL 3009, RAL 7043, Eaton-blue, CAT-yellow, RAL 9005; however, other RAL-colour shades as well as small quantities of special colour shades are also being used.

Another challenge was the fact that our coatings, which feature a very high solids content, were supposed to be processed electrostatically via high rotation atomisation by a robot. But we also overcame this problem together with the application equipment manufacturer. This allows the bulk of the hydraulic units to now be completely coated by a robot without requiring manual recoating. The units are then force dried and, after the cooling period, they are immediately ready for additional production steps.

Our coatings are tested by an independent institute regarding the specification requirements. Included are the results, which exceeded the specifications:

System Criteria 240 h 480 h 744 h 1008 h
UR1937 Gt 0 0 0 0
Primer Bg 0(S0) 0(S0) 0(S0) 0(S0)
  Ri 0 0 0 0
  Wd 0 1.7 1.7 1.7
System Criteria 240 h 480 h 744 h 1008 h
UR1937 Gt 0 0 0 0
Primer + Bg 0(S0) 0(S0) 0(S0) 0(S0)
UR1025 Ri 0 0 0 0
Top coat Wd 0 1.3 2 2
System Criteria 240 h 480 h 744 h 1008 h
UR1937 Gt 0 0 0 0
Primer + Bg 0(S0) 0(S0) 0(S0) 0(S0)
UR1409 Ri 0 0 0 0
Decklack Wd 1 1 1.3 1.3

Due to these results as well as the committed work of the participating colleagues, Linde decided in mid-2016 that FreiLacke can supply the new coating system.

Until commissioning, several theoretical and practical trainings were conducted in order to optimally prepare the newly created coating team for the task at hand.

The big moment came at the end of the last year when the first series-produced parts were coated in the new plant.