TL_240_Englisch 2012_12
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Group standard
TL 240
Issue 2012-12
Class. No.:50221
Descriptors:
zinc, phosphating, zinc phosphating, thin-layer phosphating, surface protection
Thin-Layer Zinc Phosphating Surface Protection Requirements
Previous issues
TL 240: 1986-01, 1991-11, 2004-01, 2008-01Changes
The following changes have been made to TL 240: 2008-01:
–Post-treatment with Gardolene CP 8000/1 by Chemetall incorporated in section A.2Scope
This Technical Supply Specification (TL standard) specifies the surface protection requirements for thin-layer zinc phosphating on screws, bolts, nuts and similar threaded parts.
Ofl-b149 must be used for fasteners in combination with locking coating as per DIN 267-28, sealing coating as per TL 195, microencapsulation as per DIN 267-27 and/or an alternative lubricant (e.g.as per TL 52132).Description
As per Volkswagen standard VW 13750, section 2.
1
2
Verify that you have the latest issue of the standard before relying on it.
This electronically generated standard is authentic and valid without signature.
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.
Page 1 of 5
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-2012-05m
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TL 240: 2012-12
Requirements
Surface protection types
The following degrees of protection apply.–Ofl-b140, thin-layer zinc phosphating, oiled –
Ofl-b149, thin-layer zinc phosphating, not oiled
General requirements
Approval of first supply and changes as per Volkswagen standard 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.Design and process assurance as per VW 01110-1.Coefficients of friction of Ofl-b140 as per VW 01129.
Approximately 20 parts (depending on size) are required for a complete testing. For first-sample release of small parts, e.g. threaded fastener, a test production run of ≥50 kg must be performed.Appearance and structure
Dark gray to black. The thin-layer zinc phosphating must be uniform and crystalline in structure and
exhibit firm adherence (see figure 1). Salt residues are not permissible (see appendix A,section A.1).
Figure 1 – Example structure for a
thin-layer zinc phosphating at 500x magnification
(grainy, angular, crystalline structure with a low proportion of needle-shaped formation,
grain size approx. 4 μm × 8 μm)
3 3.1
3.2
3.3