Group standard TL 196
Issue 2012-12
Class. No.: 50223
Descriptors: zinc, nickel, passivation, sealing, chromium (VI)-free, corrosion protection, surface protection, coating
systems
Duplex Coating Systems for Small Parts and Bulk Parts
Surface Protection Requirements
Previous issues
TL 196: 1995-11, 2001-10, 2004-10
Changes
The following changes have been made to TL 196: 2004-10:
– Scope supplemented by components <1 200 MPa with heat treatment
– Surface protection type Ofl-s617 removed, replaced by Ofl-s627
– Notes on temperatures to be used and repeated installations added
– Requirements for the cutting burr added
– Layer thicknesses changed
– More details given for galvanic surfaces
– Table 1 updated
– Table 3 expanded
– Table 4 added
– Released protection systems in appendix A, section A.1 expanded
– Applicable documents updated
Verify that you have the latest issue of the standard before relying on it.
This electronically generated standard is authentic and valid without signature. Page 1 of 8
The English translation is believed to be accurate. In case of discrepancies, the German version is alone authoritative and controlling.
Numerical notation acc. to ISO/IEC Directives, Part 2.
Technical responsibility The Standards department
GQL-M/1 Hans-Joachim Koeppen Tel.: +49 5361 9 25803
GQL-M/1 Günther Laudien Tel.: +49 5361 9 25846 EKDV/4 Gabriela Bochynek EKDV
GQL-M Dr. Frank Röper Tel.: +49 5361 9 21698 Manfred Terlinden
All rights reserved. No part of this document may be provided to third parties or reproduced without the prior consent of one of the Volkswagen Group’s Standards departments.
© Volkswagen Aktiengesellschaft VWNORM-2012-05k
Page 2
TL 196: 2012-12
1 Scope
This Technical Supply Specification (TL) specifies requirements for galvanically deposited zinc
coatings as per TL 217 and zinc/nickel alloy coatings as per TL 244 with an additional organic
coating based on epoxy resins (cathodic dip paint) on ferrous materials and steel parts with a ten‐
sile strength Rm ≤ 1 000 MPa as per code letter "s" specified in Volkswagen Standard VW 13750. It
furthermore defines application limits and exceptions for tensile strength values >1 000 MPa.
On principle, the alloy coatings defined in this standard must not be used for steel parts with a ten‐
sile strength Rm > 1 200 MPa and a surface hardness >370 HV. Exceptions may be made for com‐
ponents with Ofl-s621 and Ofl-s627 and a tensile strength Rm between 1 000 MPa and 1 200 MPa.
However, heat treatment as per DIN EN ISO 4042 is required in these cases.
The coatings defined in this standard are suitable for fasteners with external threads and also for
fasteners with driving recess ≥N5 as per VW 01043 and ≥T20 as per VW 01048.
Components that have metric thread and this surface protection must be used preferably only at
ambient temperatures <90 °C. Application-specific releases are required for the use at higher tem‐
peratures. Fasteners with metric thread and Ofl-s627 must be used preferably only for single-use
threaded joints.
The coating is not a standard surface protection for fasteners.
2 Designation
See VW 13750, section 2.
3 Requirements
3.1 Surface protection types
The surface protection types listed in table 1 apply.
Table 1
Surface pro‐ Characteristics and appearance
tection type
Ofl-s611 Zinc coating Ofl-c310 as per TL 217 with limited layer thickness, phosphated,
with organic coating (cathodic electrocoating), deep black
Ofl-s621 Zinc/nickel alloy coating Ofl-r642 as per TL 244 with limited layer thickness,
phosphated with organic coating (cathodic electrocoating), deep black
Ofl-s627 As for Ofl-s621, additionally treated with lubricant as per TL 52132
Page 3
TL 196: 2012-12
3.2 General requirements
Approval of first supply and changes as per VW 01155.
Avoidance of hazardous substances as per VW 91101.
The coating media used as well as the coatings must not contain any Cr(VI) compounds.
Phosphating must be used as the pretreatment for paintwork for zinc coatings and for zinc/nickel
alloy coatings. Thin-film zinc phosphating must be used preferably for fasteners. Alternative pre‐
treatment systems (e.g., passivation) are permissible for these applications only after consultation
with the laboratories "GQL-M/1" (Volkswagen AG) and/or "I/GQ-32" (Audi AG).
Lamination, voids, and pores can influence the corrosion resistance. In addition to fine stamping,
these adverse effects can be corrected by vibratory finishing. The welds on welded parts must be
coatable (free from burned oils, slag, and scale).
The cutting burr on small parts (general components) must correspond at least to the manufactur‐
ing precision "fine" as per VW 01088.
A total of 10 parts are required for complete testing.
The production process must be designed and controlled so as not to impair the functional charac‐
teristics of the finished part.
The total paint coat thickness of the coating system must not exceed the layer thicknesses as per
DIN EN ISO 4042. In metric external threads, the h-layer must not be exceeded after the coating
process (see VW 11611).
The large surface area contact points at the suspension points that are typical for rack galvanized
goods are not permissible. Individual, barely perceptible micro-contact points that do not adversely
affect the corrosion resistance in particular are permissible.
The coating procedures must follow one directly after the other (online procedure), so that interim
storage and/or transport times are significantly reduced (target value: a maximum of 48 h). With
proper mounting, the coating must not suffer any damage that would lead to impairment of function
and/or decrease of the specified corrosion protection.
For Ofl-s627, the coefficients of friction as per VW 01129 must be adhered to. Testing is performed
as per VW 01131-1 and/or VW 01131-2, but the original tightening is evaluated at room tempera‐
ture.
For bolts, the test requirements for Ofl-s611, Ofl-s621, and Ofl-s627 apply to the head and/or the
wrench bearing surfaces. For similar threaded and molded parts, these test requirements apply to
the face surfaces. The reduced requirements specified in section 3.7 apply to the shank and
thread.
As a process-inherent phenomenon, accumulation of coagulate on the coated parts cannot be reli‐
ably ruled out due to contacting during the coating process of the bulk parts. To ensure the installa‐
bility of the parts, a 100% visual inspection for the accumulation of coating must be performed.
Page 4
TL 196: 2012-12
3.3 Base material
Material as per the drawing or master data list (MDL).
3.4 Color
Black RAL 9005.
3.5 Coating thicknesses
See table 2. In the thread and in the driving recess, the layer thickness must be reduced depend‐
ing on the system.
Table 2 – Layer thickness (in µm)
No. Application and Ofl Zinc and zinc/nickel Organic coating (cathodic Total paint coat thick‐
coating electrocoating) ness
for fasteners Ofl-s621
1 6 to 12 (Ofl-r642) 6 to 12 12 to 18
with external thread Ofl-s627
Ofl-s611 8 to 15 (Ofl-c310) 18 to 25
2 for general components 10 to 15
Ofl-s621 6 to 10 (Ofl-r642) 16 to 25
3.6 Adhesion and brittleness
Cross-cut test as per DIN EN ISO 2409 with adhesive tape removal after 2 h waiting time.
Requirement: ≤ characteristic value 1.
Alternatively, the adhesion for small parts and fasteners can be evaluated with a scribing line as
per DIN EN ISO 9227 with subsequent adhesive tape removal as per DIN EN ISO 4628-8. Re‐
quirement: no stripping of coating.
3.7 Corrosion behavior
3.7.1 Test in condensation atmosphere with constant humidity
Testing in CH test atmosphere as per DIN EN ISO 6270-2 with a scribing line as per
DIN EN ISO 9227, test duration 240 h, then at least 30 min (max. 60 min) acclimatization at room
temperature. The results are evaluated as per DIN EN ISO 4628-8.
Requirement outside of the scribing line: no blisters, no corrosion of coating and base metal.
Requirement on the scribing line: loss of adhesion d < 1 mm.
In addition, the coating adhesion requirements as per section 3.6 must be fulfilled after the test in
the condensed water constant climate.
Requirement: ≤ characteristic value 1.
Page 5
TL 196: 2012-12
3.7.2 Corrosion cycle test
Test as per Test Specification PV 1210 with scribing line as per DIN EN ISO 9227, and then adhe‐
sion testing as per section 3.6. The results are evaluated as per DIN EN ISO 4628-8.
Requirements as per table 3.
Table 3
Requirements
Test cy‐ Ofl-s611 Ofl-s621, Ofl-s627
cles General components General components Fasteners with external thread
5 No surface changes, including cut edges and welds No surface changes
Surface free from base metal cor‐ Surface free from base metal cor‐
Surface free from base metal cor‐
rosion (rust) and blister formation, rosion (rust) and blister formation,
rosion (rust) and blister formation,
no coating corrosion, including cut no coating corrosion, including cut
15 no coating corrosion,
edges and welds, edges and welds,
adhesion loss at the scribe
adhesion loss at the scribe adhesion loss at the scribe
d < 1,5 mm
d < 2,5 mm d < 1,5 mm
Surface free from base metal cor‐
rosion (rust) and blister formation,
Surface free from base metal cor‐
no coating corrosion, including cut Surface free from base metal cor‐
rosion (rust) and blister formation,
edges and welds, rosion (rust) and blister formation,
30 including cut edges and welds,
adhesion after cross-cut test adhesion loss at the scribe
adhesion after cross-cut test
≤ characteristic value 1, d < 1,5 mm
≤ characteristic value 1
adhesion loss at the scribe
d < 1,5 mm
Surface free from base metal cor‐
rosion (rust) and blister formation,
60 Omitted Omitted
adhesion loss at the scribe
d < 2,5 mm
Page 6
TL 196: 2012-12
3.8 Resistance to chemicals
The resistance to chemicals must be tested and ensured by the paint supplier.
Testing in oils and brake fluid only for parts used in the engine compartment.
In first-sample testing, the resistance to chemicals may also be demonstrated by a certificate is‐
sued by the coating material manufacturer.
For test media and requirements, see table 4. The resistance is evaluated as per
DIN EN ISO 4628-1.
Table 4
No. Test medium and test requirement Requirement
1 E10 gasoline as per DIN 51626-1, ethanol content 9%
to 10% (V/V): Testing as per DIN EN ISO 2812-3, room
temperature, 10 min, filter
2 B7 diesel fuel as per TL 788-B: Testing as per
DIN EN ISO 2812-3, room temperature, 60 min, filter
3 Reference engine oil as per TL 52185 (Lubrizol
Characteristic value ≤1
OS 206 304): Testing as per DIN EN ISO 2812-4, room
temperature, 16 h, dripping
4 Hydraulic fluid as per TL 52146: Testing as per
DIN EN ISO 2812-3, room temperature, 16 h, filter
5 Coolant as per TL 774: Testing as per
DIN EN ISO 2812-3, room temperature, 60 min, filter
Characteristic value ≤1; swellings
Brake fluid as per TL 766: Testing as per
6 that have disappeared after 24 h
DIN EN ISO 2812-3, room temperature, 60 min, filter
are permissible.
4 Applicable documents
The following documents cited in this standard are necessary to its application.
Some of the cited documents are translations from the German original. The translations of Ger‐
man terms in such documents may differ from those used in this standard, resulting in terminologi‐
cal inconsistency.
Standards whose titles are given in German may be available only in German. Editions in other
languages may be available from the institution issuing the standard.
PV 1210 Body and Add-on Parts; Corrosion Test
TL 217 Zinc Coatings; Surface Protection Requirements
TL 244 Zinc/Nickel Alloy Coatings; Surface Protection Requirements
TL 52132 Lubricant for Threaded Fasteners with Electrolytically Applied Coatings
or those of Stainless Steel; Requirements
TL 52146 Central Hydraulic System Fluid; Lubricant Requirements
TL 52185 Reference Engine Oil SAE 5W-30 for Testing of Compatibility with Re‐
spect to Elastomer Materials; Lubricant Requirements
Page 7
TL 196: 2012-12
TL 766 Brake Fluid; Material Requirements
TL 774 Ethylene Glycol-Based Coolant Additive; Material Requirements
TL 788 Diesel Fuel; Fuel Requirements
VW 01043 Multipoint Socket Profile; Drive Shape for Threaded Parts
VW 01048 Hexalobular Socket Profile; Drive Shape for Threaded Parts
VW 01088 Workpiece Edges; Definitions, Drawing Specifications
VW 01129 Limit Values for Coefficients of Friction; Mechanical Fasteners with Met‐
ric ISO Threads
VW 01131-1 Determination of Coefficients of Friction; Practice- and Mounting-Orien‐
ted Testing
VW 01131-2 Determination of Coefficients of Friction; Release of New Surface Coat‐
ing Systems
VW 01155 Vehicle Supply Parts; Approval of First Supply and Changes
VW 11611 Metric ISO Thread; Limit Dimensions with Protective Coating for Medium
Tolerance Class; External Threads 6gh / Internal Threads 6H
VW 13750 Surface Protection of Metal Parts; Surface Protection Types, Codes
VW 91101 Environmental Standard for Vehicles; Vehicle Parts, Materials, Operat‐
ing Fluids; Avoidance of Hazardous Substances
DIN 51626-1 Automotive fuels - Requirements and test methods - Part 1: Petrol E10
DIN EN ISO 2409 Paints and varnishes - Cross-cut test
DIN EN ISO 2812-3 Paints and varnishes - Determination of resistance to liquids - Part 3:
Method using an absorbent medium
DIN EN ISO 2812-4 Paints and varnishes - Determination of resistance to liquids - Part 4:
Spotting methods
DIN EN ISO 4042 Fasteners - Electroplated coatings
DIN EN ISO 4628-1 Paints and varnishes - Evaluation of degradation of coatings - Designa‐
tion of quantity and size of defects, and of intensity of uniform changes
in appearance - Part 1: General introduction and designation system
DIN EN ISO 4628-8 Paints and varnishes - Evaluation of degradation of coatings - Designa‐
tion of quantity and size of defects, and of intensity of uniform changes
in appearance - Part 8: Assessment of degree of delamination and cor‐
rosion around a scribe
DIN EN ISO 6270-2 Paints and varnishes - Determination of resistance to humidity - Part 2:
Procedure for exposing test specimens in condensation-water atmos‐
pheres
DIN EN ISO 9227 Corrosion tests in artificial atmospheres - Salt spray tests
Page 8
TL 196: 2012-12
Appendix A (informative)
A.1 The Volkswagen Group has released parts with the following protection systems
– Cr(VI)-free Duplex 2000 (PPG Powercron, binder 645A, paste CP639 or PPG Powercron
6000, binder CR 691, paste CP 639Q) coating systems, Hillebrand (hurdle technology for gen‐
eral components), for Ofl-s627 with lubricant treatment as per TL 52132.
– Cr(VI)-free Duplex coating as bulk parts (Doerken coating, designation EC 800, for Ofl-s627
with lubricant treatment VH 315), Klever, Hillebrand, Leist
– Cr(VI)-free Duplex coating as bulk parts (PPG Powercron, binder CR648A or CR691K-C4 and
paste CP639 or CP639Q-H6, for Ofl-s627 with lubricant treatment as per TL 52132, ITW
