Group Standard TL 233

Issue 2010-11
Class. No.: 50223

Descriptors: corrosion protection, surface protection, zinc, aluminum, flake, top coat, DELTA-TONE, DELTA-SEAL,
DELTA-PROTEKT, Magni

Non-Electrolytically Applied Zinc Flake Coatings with Top Coat

Surface Protection Requirements

Previous issues
TL 233: 1982-09, 1983-02, 1991-05, 1992-06, 1993-11, 1998-02, 2003-09, 2003-11

Changes
The following changes have been made compared with TL 233: 2003-11:
– Scope changed: Maximum temperature 180 °C for general components, notes on TL 180 added
– Tables 1 and 2 changed
– Base layer and specifications supplemented in Section 3.6.2
– Requirement in Section 3.9.2 changed
– Section 3.10 revised
– Referenced standards updated
– Appendix A, new products DELTA-PROTEKT® KL 101, DELTA-PROTEKT® KH 200, as offered
by Dörken MKS-Systeme and Magni-Flake D21 and B46, as offered by Magni Europe included

1 Scope
This standard defines the requirements for non-electrolytically applied surface protection types made
of zinc and aluminum flakes (at least 70%) with an additional organic top coat for ferrous materials.
In contrast to the surface protection types specified in Technical Supply Specification TL 180 (cur‐
rently being prepared) and TL 245, this standard describes a coating system which ensures the
QUELLE: NOLIS

functional characteristics of components, e.g., color and/or corrosion protection, by means of a con‐
sistent organic top coating with a greater coating thickness. The layers are applied using the following
methods: spray coating, spin coating, or electrostatic spray coating. The dip/spin coating method is
especially suitable for small parts.

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 convention.

Technical responsibility Standards Department

GQL-LM/2 Hans-Joachim Koeppen Tel.: +49 5361 9-25803
GQL-LM/2 Günther Laudien Tel.: +49 5361 9-25846 EKDV/4 Jürgen Wiesner EKDV
GQL-L Dr. Stephan Eisenberg Tel.: +49 5361 9-21151 Tel.: +49 5361 9-29064 Manfred Terlinden
Confidential. All rights reserved. No part of this document may be provided to third parties or reproduced without the prior consent of the Standards Department of a Volkswagen Group
member.
This Standard is available to contracting parties solely via the B2B supplier platform www.groupsupply.com.
© Volkswagen Aktiengesellschaft VWNORM-2010-08e
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TL 233: 2010-11

Surface protection according to TL 233 can be used for maximum temperature loads of up to 180 °C
(exception: DELTA-TONE® 9000, as offered by Dörken MKS-Systeme, max. 120 °C). The color of
the surface protection according to TL 233 is generally black. However, it can also have different
colors if required and specified accordingly. If silver color is required (e.g., for metric screws), surface
protection according to TL 245 s is to be preferred.
For newly designed parts, surface protection types acc. to TL 180 are to be preferred for fasteners
with metric threads.
Since, with proper pretreatment, hydrogen embrittlement is not to be expected as a result of the
coating process, this coating can also be used as corrosion protection for hardened and high-strength
steel parts with tensile strength values ≥ 1000 MPa or surface hardness values > 320 HV.
The coating is not suitable for the components given below:
– Components serving as electrical conductors (e.g., ground connections).
Coatings for the following elements must be released separately depending on the application:
– Metric threaded parts ≤ M8 with specific requirements regarding the loosening torques of the
joint at temperatures > 80 °C,
– External threads ≤ M6 and internal threads < M10,
– Triple square force application acc. to VW 01043, nominal size < 8,
– Hexalobular socket acc. to VW 01048, < T30,
– Hexagon socket < 5
– Cross recessed head acc. to DIN EN ISO 4757, < H3.

2 Description
See Volkswagen Standard VW 13750, Section 2.

3 Requirements

3.1 Surface protection types

The surface protection types listed in Table 1 apply. The released surface protection types are listed
in the Appendix, Section A.1.
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TL 233: 2010-11

Table 1
Protection type Characteristics and appearance
Ofl-t330 Zinc flake coatinga) with top coat, blackb); medium corrosion protection;
not for standard parts and exposed installation positions, but for drawing parts
mainly used in the vehicle interior (e.g., seat belt buckle).
Ofl-t350 Zinc flake coatinga) with top coat, blackb); medium corrosion protection;
not for threaded parts with Metric ISO threads and parts in exposed installation
positions, but for drawing parts mainly used in vehicle interior
Ofl-t630 Zinc flake coatinga) with top coat containing lubricant, blackb); for use in exposed
installation positions; e.g. in body.
Ofl-t650 Zinc flake coatinga) with top coat, blackb); for use in exposed installation positions;
e.g. in chassis.
a) Baking temperature 200 °C to 250 °C (baking temperature 300 °C for DELTA-PROTEKT® KH 200).
b) As a standard, a black top coat is applied. However, if the coatings are to be in color, this must be mentioned on the drawing or the
master data list (for example, surface protection type 630, blue).

3.2 General requirements

Approval of first supply and changes according to VW 01155.
Avoidance of hazardous substances according to VW 91101.
Approximately 10 parts (depending on size) are required for a thorough testing. For first-sample
release of small parts, e.g., fasteners, a test production of ≥ 50 kg must be performed.
The coating media used as well as the coatings must not contain any Cr(VI) compounds.
Unless certain sections of a part that are marked in the drawing are excluded from the surface coating,
the entire surface of the parts must comply with the required surface protection type and display the
prescribed properties.
The protective layers must not exhibit any pores, cracks, damage or other flaws impairing corrosion
protection and/or specified appearance. The surface protection types must firmly adhere to the base
material; there must be no flaking or cracks on the coating under elastic deformation.
The coating must be free of flaws and excess material impairing the part’s function. Metric internal
and external threads are to be designed according to VW 11611. After the coating process, the zero
line must not be exceeded in the case of external threads, and it must not be fallen below in the case
of internal threads. Fasteners with metric threads must comply with the coefficients of friction ac‐
cording to VW 01129 (only applies to Ofl-t330 and Ofl-t630).
The production process must be designed and controlled such that functional characteristics of the
finished part are not impaired.
If the coated components are properly mounted, the coating must not be damaged in a way that would
result in impairment of function and/or in the reduction of the specified corrosion protection.
Manufacturer, surface protection types as well as the coating process are selected on a part-specific
basis and must be agreed upon with the responsible department before use (GQL-LM/2, N/GQ-551,
I/GQ-322, I/EG-72).

3.3 Base material

See drawing or master data list (MDL).
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TL 233: 2010-11

3.4 Pretreatment
Bright metal surface; microcrystalline zinc phosphating (1 to 3 g/m2) is optionally permissible.
In the case of hardened and high-strength steel parts with tensile strength values > 1000 MPa, alkaline
or mechanical cleaning (e.g., by abrasive blasting) must always be carried out prior to coating.

3.5 Color
Black or colored acc. to drawing or MDL.

3.6 Dry film

3.6.1 General
Composition acc. to International Material Data System (IMDS).

3.6.2 Base layer

Inorganic zinc flake coatings, with globular structure if applicable, with a Zn proportion of > 70 percent
by weight and an Al flake proportion of up to 10 percent by weight (for Magni-Flake, only Zn with
globular structure plus inorganic binder system). The use of zinc dust is not permissible.

3.6.2.1 Top coating

Organic epoxy resin coating with no more than 5 percent by weight lubricant (PTFE).

3.6.2.2 Top coating containing lubricant

Organic epoxy phenolic resin coating with 25 to 30% lubricant (PTFE) by weight.

3.7 Dry film thickness

Testing acc. to DIN EN ISO 1463, DIN EN ISO 2064 and DIN EN ISO 2178; position of measuring
points and tolerance zone positions for threaded parts with Metric ISO thread acc. to
DIN EN ISO 10683.

3.7.1 Requirements for Ofl-t330 and Ofl-t350

Minimum layer thickness 6 µm (with at least 3 µm of zinc flake coating);
Maximum layer thickness 25 µm.

3.7.2 Requirements for Ofl-t630 und Ofl-t650

In the case of threaded parts, the specifications only apply to the head and/or to the face and wrench
bearing surfaces.
Minimum layer thickness 10 µm (with at least 3 µm of zinc flake coating).
Maximum layer thickness 25 µm. Thicker layers are permissible if there are higher corrosion protec‐
tion requirements as compared to the basic requirements, for example, for spring clamps (see
Section 3.9.2.4).
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TL 233: 2010-11

3.8 Adhesion and ductility

3.8.1 Cross-cut test

This test is to be carried out in accordance with DIN EN ISO 2409, requirement: ≤ characteristic value
1.

3.8.2 Tape test

Test procedure: adhesive tape with an adhesive strength of (7±1) N per 25 mm width is used for the
adhesion test acc. to DIN EN ISO 10683. It must be firmly pressed onto the specimen surface by
hand and then removed with a jerk-like motion perpendicular to the surface. Coating must not be
removed from a large area. Small particles of the coating material that adhere to the tape are per‐
missible.

3.8.3 Ductility
The coating must not exhibit any flaking when springs expand or contract acc. to specifications or
when spring washers are bent during assembly.

3.9 Corrosion behavior

3.9.1 Load in condensation atmosphere with constant humidity

This test is to be carried out in the CH test atmosphere acc. to DIN EN ISO 6270-2.
Requirement: no blisters or other signs of coating separation and no base metal corrosion after 240 h.
After subsequent acclimatization for 24 h at (23 ± 2) °C, the requirements specified in Section 3.8
are still to be fulfilled.

3.9.2 Resistance to salt spray fog

NSS salt spray test and scribing line acc. to DIN EN ISO 9227.
For nuts and bolts, the test requirements apply only to the head, face and/or wrench bearing surfaces.
For threaded and thread-like parts, e.g., tap end studs , they apply to the face surfaces. Reduced
requirements apply to the thread area. These are described in the following Sections.

3.9.2.1 Requirements for the top coat layers

Coating corrosion up to a maximum of degree of change S5 acc. to DIN 34804, is permissible after
120 h (for all surface protection types) with and without thermal conditioning (aging at elevated tem‐
perature/recirculated air) for 96 h at +180 °C.
A reduced requirement of 72h is applicable to the threaded area.

3.9.2.2 Requirements for general components with Ofl-t330 or Ofl-t350

No base metal corrosion, no corrosion creepage along scribe line after 240 h with and without thermal
conditioning (aging at elevated temperature/recirculated air) for 96 h at +180 °C.
A reduced requirement of 120 h is applicable to the threaded area.
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TL 233: 2010-11

3.9.2.3 Requirements for general components with Ofl-t630 oder Ofl-t650

No base metal corrosion, no corrosion creepage along scribe line after 480 h with and without thermal
conditioning (aging at elevated temperature/recirculated air) for 96 h at +180 °C.
A reduced requirement of 240 h is applicable to the threaded area.

3.9.2.4 Requirements for spring clamps (Ofl-t650)

No base metal corrosion, no corrosion creepage along scribe line after 720 h with and without thermal
conditioning (aging at elevated temperature/recirculated air) for 96 h at +180 °C.

3.10 Resistance to chemicals

Testing in oils and brake fluid only for parts used in the engine compartment.
Testing according to VDA 621-412 in the following media:
premium unleaded gasoline according to DIN EN 228 and VDA 621-412, test A4.1.3 Y,
diesel fuel according to TL 788 and VDA 621-412, test A4.1.2 X,
reference engine oil according to TL 52185 (Lubrizol OS 206 304) and VDA 621-412, test A4.1.4 X,
hydraulic fluid according to TL 52146 and VDA 621-412, test A4.1.6 X,
coolant according to TL 774 and VDA 621-412, test A4.2.2 X.
Surface changes are not permissible in any event.
Additional testing in brake fluid according to TL 766 and VDA 621-412, test A4.2.1 X. The following
requirement applies to this medium: swellings that have disappeared after 24h are permissible.

4 Other 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 German
terms in such documents may differ from those used in this Standard, resulting in terminological
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.

TL 245 Non-Electrolytically Applied Zinc Flake Coatings; Surface Protection Re‐

quirements
TL 52146 Central Hydraulic System Fluid; Lubricant Requirements
TL 52185 Reference Engine Oil SAE 5W-30 for Testing of Compatibility with Respect
to Elastomer Materials; Lubricant Requirements
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
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TL 233: 2010-11

VW 01129 Limit Values for Coefficients of Friction; Mechanical Fasteners with Metric
ISO Threads
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, Operating
Fluids; Avoidance of Hazardous Substances
DIN 34804 Fasteners - Change of appearance of black surfaces
DIN EN 228 Automotive fuels - Unleaded petrol - Requirements and test methods
DIN EN ISO 10683 Fasteners - Non-electrolytically applied zinc flake coatings
DIN EN ISO 1463 Metallic and oxide coatings - Measurement of coating thickness - Micro‐
scopical method
DIN EN ISO 2064 Metallic and other non-organic coatings - Definitions and conventions con‐
cerning the measurement of thickness
DIN EN ISO 2178 Non-magnetic coatings on magnetic substrates - Measurement of coating
thickness - Magnetic method
DIN EN ISO 2409 Paints and varnishes - Cross-cut test
DIN EN ISO 4757 Cross recesses for screws
DIN EN ISO 6270-2 Paints and varnishes - Determination of resistance to humidity - Part 2:
Procedure for exposing test specimens in condensation-water atmo‐
spheres
DIN EN ISO 9227 Corrosion tests in artificial atmospheres - Salt spray tests
VDA 621-412 Chemikalienbeständigkeit von Kraftfahrzeug-Lackierungen
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TL 233: 2010-11

Appendix A (informative)

A.1 Released surface protection systems

Only the products DELTA-PROTEKT® KL100, DELTA-TONE® 9000, and DELTA-SEAL® GZ are
released for threaded parts with metric ISO threads (see Table A.1).

Table A.1
Ofl-t630 Ofl-t330 and Ofl-t630 Ofl-t350 und Ofl-t650
(for threaded parts with Metric (for general components) (for general components)
ISO thread)
Base layer DELTA-PROTEKT® KL 100, DELTA-PROTEKT® KL 100, as offered by Dörken MKS-Systeme,
as offered by Dörken MKS-Sys‐ DELTA-PROTEKT® KL101, as offered by Dörken MKS-Systeme,
teme, DELTA-PROTEKT® KH 200, as offered by Dörken MKS-Systeme,
DELTA-TONE® 9000, DELTA-TONE® 9000, as offered by Dörken MKS-Systeme,
as offered by Dörken MKS-Sys‐ Magni-Flake D21 or B46, as offered by Magni Europe
teme
Top coat DELTA-SEAL® GZ, DELTA-SEAL® GZ, DELTA-SEAL®
(generally black, as offered by Dörken MKS-Sys‐ as offered by Dörken MKS-Sys‐ as offered by Dörken MKS-Sys‐
optionally col‐ teme, teme, teme,
ored) Magni-Top GZ, Magni-Top,
as offered by Magni Europe as offered by Magni Europe