application report- 9 thyssenkrupp(22 08 2014) rewitec gmbh dr.-hans-wilhelmi-weg 1 d-35633 lahnau...

REWITEC GmbH Dr.-Hans-Wilhelmi-Weg 1 D-35633 Lahnau

Tel. +49 (0)6441 44599-0 Fax +49 (0)6441 44599-25 www.rewitec.com [email protected]

Test report

Transfer case

Client: ThyssenKrupp Steel Europe AG

Kaiser-Wilhelm-Straße 100

47166 Duisburg

Sector: Industry

Plant: Transfer case (Run in and out)

Cold strip mill I, Pickle

Picture 1: Manufacturing



Project Task

The Transfer case has some microscopically surface damages, pitting and micros-pitting.

Provided by the addition of REWITEC® DuraGear® 100 should be improve the effectiveness of

the coating in the gear boxes. The analysis will be done by the help of the teeth surfaces by

using the REWITEC Replica Set (surface imprints) before and after < 100 hours after the

treatment on the tooth flank.

For appraisal of the current condition one of the tooth flanks was selected. This was cleaned

and marked using an oil-resistant dye so that it could be found again on the second

inspection.

Background

The transfer case with run in and run out stands in the cold string mill 1 pickling. Where metal

plates stretched so that the surface cracks. Next, the surface is cleaned from impurities.

Since the gear working against each other creates relative high stresses which can lead to

strong material strains.



Picture 2: detail picture of manufacturing

Technical data of the Transfer case

Oil volume: c. 2.200 liters

Oil type: CLP 220

Last service: August and December 2013

Work carried out

For appraisal of the current condition two of the tooth flanks was selected from each gear.

This was cleaned and marked using an oil-resistant dye so that it could be found again on the

second inspection.

Run-out gear:

- Massive micro-pitting on the tooth flank

- Grooves of medium severity on the tooth flank

- Electrical resistance up to 20 ohms measurable

-

Picture: Imprints area run-out area before the treatment



Run-in gear:

- Upper area of the tooth flank is very rough

- Lower area of the tooth flank has some big pittings

- Electrical resistance up to 15 Ohms measurable

Picture 4: Imprint area run in gear before the treatment

A surface imprint was taken using 2-component silicon (REWITEC Replica) on both tooth

flanks.



Analysis

The tooth flank was inspected again on 28.05.2014. Based on the differing revs, could only be

achieved that marked position of the out run gear was on the right place. For this reason

there was only the chance to do the second surface imprint from the run out gear.

Run out gear:

- The rough pittings in the tooth base are felt much smoother

- Furthermore, a grey stripe (coating) is in the foot area to identify

- Electrical resistance up to 170 Ohms measurable

- The tooth flanks seem to be improved

Picture 5: Imprint area run out gear after the treatment



Analysis of the Imprints

The following pictures were photographed from the surface imprints to evaluate the

macroscopic surface structure, before and after the treatment.

Picture 6: Macroscopic surface imprint before the treatment

Picture 7: Macroscopic surface imprint after the treatment

- Various significant differences of the both surfaces

- Significant lower pitting structure on the tooth flank



The imprints were examined under a microscope with 200x resolution. The following could be

identified very clearly.

Picture 8: Before the treatment

- Strips with micro-pitting

- Rough surface structure

Picture 9:



- Micro-pitting has gone

- Surface is smoother

Analysis part 2

The tooth flank was inspected again on 06.08.2014.Based on the differing revs, could only be

achieved that marked position of the out run gear was on the right place. For this reason

there was only the chance to do the second surface imprint from the run in gear.

Run in gear

- The rough pittings in the tooth base are felt much smoother

- Furthermore, a grey stripe (coating) is in the foot area to identify

- Electrical resistance up to 225 ohms measurable

The tooth flanks seem to be significant improved -

Picture 10: Imprint area run in gear before the treatment



Analysis of the Imprints




Picture 12: After the treatment

- The areas of the rough surface disappeared

- Surface is smoother






- rough surface

- Micro Pitting

Picture 14: After the treatment

- Surface is much smoother than before

- Micro Pitting are partly blocked



Results

Based on the analyses of the surface imprints from the 02.04.2014 before the REWITEC®

treatment and the surface imprints after the treatment after 8 weeks (28.05.2014) and 18

weeks (06.08.2014) later it can be established that the condition of the gear surfaces has

changed considerably. The following conclusion that can be stated is that:

- The surface of the tooth flanks have been shown to improve (engaging surface,

supporting images), which means significantly less stress on the components

- Straps, pitting’s, micro-pitting’s and outbreaks are reduced, in some cases be

significantly reduced

- Electrical resistance up from 15 ohms to 225 ohms at in run gear and at the out run

gear the electrical resistance risen up from 20 ohms to 170 measurable, what is

characterized by a passivating silicon into the surface.

Summary The aim of the REWITEC® DuraGear® is very clear to see of freezing / improving the current condition

by adding the wear-protection coating has thus been fully achieved.

The improved surface of the tooth flank and the bearings should extension the life-time.

On the basic of the practical results had confirm to the test results of the Competence Center for

Tribology of Mannheim University of Applied Sciences examined with a rolling wear tester the effect

of REWITEC in gear oils under rolling-sliding motion.

We recommend performing a thorough treatment again after no more than 2 years. However, it

would be better to top up the treatment annually in order to give the gearbox lasting protection with

reduced dosage.

application report- 9 thyssenkrupp(22 08 2014) rewitec gmbh dr.-hans-wilhelmi-weg 1 d-35633 lahnau...

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