October 2008
Mercedes-Benz
Supply Specification
Coating / Painting for Parts with
High Corrosive Stress
DBL 7391
BQF available
Additional DaimlerChrysler Standards required:
DBL 7399, 7390, 7392, 8585, 6714 and MB Special Terms. In addition, Directive 2000/53/EC of the European Parliament and Council of 2000-09-18 regarding end-of-life vehicles (ELV) shall be observed. Supersedes
edition: 04/2006:
Continued on pages 2 to 21
Issued by: DaimlerChrysler AG  D-70546 Stuttgart Standards; Telephone: +49(0)711 17-4 10 40 Technical responsibility (Name): Petra  Emmert @daimlerchrysler Department:  PWT/VBT  Plant: 050
Telephone:  +49(0) 70 31 90-37 75 HPC: E 430
Technical coordination by PWT / Materials and Process Engineering Plant 050, Department PWT/VBT: Dr.Rolf Specht
Telephone +49(0)7031 90-53 26    HPC: B 515
Product versions (PV) and application examples
General: Finish coat (top coat) for components subject to high corrosive stress, and - if applicable - also mechanical stress.
This DBL applies to coatings on the outer side and underside of vehicles and in the engine compartment.
Corrosive stress
Specific additional requirements Type of coating Application examples high long
term high
00* 50 Operating fluids in the
engine compartment Air or force-dried single or multicoat finishes Components in engine compartment, brackets, struts, engine shock absorbers, radiators, signaling horns
01* - as for PV 00
Air or force-dried single-coat finishes
Cast iron parts such as engine, transmission and steering gear housings, clutch and brake cylinders, forged parts
02* 52 Compatibility during product manufacturing as for PV 00/50 Metal-rubber parts such as engine and chassis mounts, vibration dampers/absorbers on crankshafts and propshafts 03* 53 as for PV 00
as for PV 00
High-build coating
as for PV 01
04
54
Run-free painting
high corrosion protection (non decorative,
non weather resistant, not stone chip resistant) Single-coat finish from hot-set electrophoretic paints (anaphoretic/cataphoretic dip coating)
Steel sheet drawn/pressed parts, steel disk wheels, air filters, pulleys, brake units
10 * 60
Stone-impact resistant  coating
Stone-impact resistant air or force-dried single or multicoat finishes
Vehicle underside, chassis/axle parts, shock absorbers, coil springs, torsion bars, tie rods and drag links, longitudinal and crossmembers of commercial vehicle chassis, brake/compressed air reservoirs
20*  Coating suitable for spot welding
Single-coat finish from air-dried one- or two-component paints
Bus substructure sheet stiffening, Unimog frame and attachment parts
30
80 High mechanical resistance
Powder coating or equivalent high-build coating
pulleysPassenger car underside/engine compartment,  bus seat frames and interior parts up to waistrail height, bus underfloor coating, attachment parts, engine blocks, oil pans, cylinder head covers, brake/compressed air reservoirs
31 * - as for PV 30/80 as for PV 30/80
Interior fittings for buses above waistrail height 40 *
90
Decorative appearance, weather resistant
Single/multicoat finish,
predominantly from baked paints
Body and/or attachment parts, Al disk wheels, mirror frame, ventilation window frame, air inlet grille, door handles, wiper arms/blades
*  Not for new design
Abbreviated designation:
For drawings in the block for surface protection      e.g.: DBL 7391.00
On the underfloor, PVs "long term/high" shall be used PV 04/ 30 only for the engine compartment area
Replacement remarks: For PV 01  PV 03 / 53
For PV 20  DBL 7390.20 or DBL 7390.21
For PV 31  DBL 7392.40
1Field of application, general requirements
Product versions with light alloys as base material
1.1.1  Aluminum alloys
1.1.1.1  Extruded aluminum parts / Rolled aluminum
The CASS test and/or the filiform test according to 4.17 shall be performed as approval-relevant corrosion test.
1.1.1.2 Aluminum die casting
The CASS test without scribe shall be performed as approval-relevant corrosion test.
1.1.1.3 Aluminum sand casting/Aluminum chill casting
The CASS test shall be performed as approval-relevant corrosion test.
1.1.1.4 Mirror-turned / polished aluminum wheels
The filiform corrosion test according to Section 4.17 shall be performed as approval-relevant corrosion test for mirror-turned parts. CASS test for three-layer structure.
1.1.2 Magnesium die casting / Zinc die casting
The corrosion cycle test shall be performed as the approval-relevant corrosion test .
To check the coverage of the whole surface, the CASS test can be used as accelerated test.
(This test is performed without scribing the surface).
1.1.3 Other substrates
Approval-relevant corrosion tests shall be agreed with the responsible department.
2General properties of the materials, raw materials and supply condition
2.1All product versions
The materials (cleaning and phosphating agents) used for pretreatment before coating, the binder types and pigments used for the paintwork structure as well as the coating methods and the drying types shall be disclosed to the receiving MB plant for initial samples and in the event of changes. This stipulation is intended to facilitate, in particular within the framework of development processes, the general material assessment and compliance with any necessary technical and/or personal protective measures for the processing of painted components (e.g. grinding, welding).
The pretreatments and coatings shall be free of heavy metals and their compounds such as arsenic, cadmium, mercury, chromium-VI compounds or lead. In addition, DBL 7399, Section 1.2.1, DBL 8585 and DBL 6714 as well as directive
2000/53/EC of the European Parliament and Council of 2000-09-18 regarding end-of-life vehicles (ELV) or the latest version of the ELV directive shall be observed.
Exception:
The requirements regarding "Chromium-VI compounds and lead-free" refer to new designs or new samples.
Production parts shall be adapted within the statutory transitional periods following agreement with the responsible department.
Pretreatment, coating material and coating processes shall be selected by the part supplier so as to fulfill the requirements of this DBL. Residues which could promote corrosion and/or impair adhesion of the coating (flux, scale, organic contamination residues from assembly or other processing steps) shall be removed chemically or mechanically, in particular from weld seams or from laser-cut edges.
Edges, corners, overlaps and points accessible only with difficulty which are subject to the risk of corrosion shall be treated particularly carefully.
The surface shall be free of any visible roughness, craters, dust inclusions etc.
2.2Initial sampling
The corrosion-relevant documents of the initial sample inspection report (ISIR) to PWT/VBT or the responsible department of the receiving MB plant shall be attached in the SQMS system (if available) under ISIR plants - surfaces-corrosion testing, and include the following information:
Indication of the production and coating location. If the component is produced or coated at several locations, these locations shall be listed separately including the following data for each location. In addition, one component shall be submitted for sampling for each production/coating location.
-  Pretreatment materials, product name with product code, supplier
-  Coating materials, product name with product code (for cataphoretic dip coats also binder and pigment paste) supplier, in addition an electronic IR-ATR spectrum in JCAMP/DX format of a paint layer stoved under normal process conditions with a thickness of at least 10 µm shall be submitted
-  Process description (flow chart)
-  Process parameters, test frequency
-  Layer thickness and tolerances, layer thickness measuring points (illustrated documentation), test frequency
-  Object stoving temperature (ideal, minimum, maximum),
- Object temperature curve (at full load)
-  Object temperature measuring points (illustrated documentation), test frequency
-  Corrosion test report (illustrated)
-  Requalification measures, test frequency (at least according to MB Special Terms No. 14) corrosion tests, technical-mechanical properties in analogy with Section 6.2 of this DBL
-  Repair paintwork: work instruction, coating materials with product and supplier name,
Corrosion test report for this repair concept (illustrated)
2.3Changes (material, process)
Any changes shall be notified to the MB receiving plant in good time according to VDA volume 2 and MB Special Terms No. 13 and initial sampled and approved before production application.
2.4Assemblies
Note that this DBL applies to the testing of individual components. If these components are installed with other components which might have an influence on the overall corrosion result after stressing (e.g. conductive rubber components, material combinations which run the risk of contact corrosion creation etc.), relevant corrosion tests in the corresponding assembly condition shall be agreed.
2.5MAG weld seams / heat-affected zone
MAG weld seams shall be pretreated so that silicate and slag residues are removed to an extent that allows proper phosphating/coating. The heat-affected zone shall be treated in the same way, if it is accessible.
Possibilities: ceramic blasting, barrel finishing etc. In individual cases, an additional coating on the weld seams is also possible. It depends on the component which of these possibilities mentioned makes sense, and it should therefore be selected following discussions with the responsible Daimler AG department.
2.6Punched and cut edges
Punched and cut edges shall be designed such that compliance with the edge protection required in th
e relevant PV is reliably ensured. The following rework possibilities are available for edge protection: grinding, brushing, barrel finishing, shot peening etc. If the parts are laser cut, an oxygen-free cut shall be chosen. Where this is not possible, the edges shall be finished as described above.
2.7Cavity coating
The minimum layer thickness of the cataphoretic dip coating in cavities shall be 12 µm. A complete flow through the parts shall be ensured. If air bubbles cannot be avoided for design reasons, these air bubbles shall be shifted to areas which are non-critical with regard to corrosion and functionality by suspending the parts appropriately.
If required, additional measures (waxing etc.) shall be taken.
2.8Cataphoretic dip coating material and pretreatment
The supplier shall ensure that the phosphate content in the cataphoretic dip coating bath does not exceed 100 ppm as corrosion protection deteriorates significantly with increasing phosphate content. PWT/VBT and the relevant MB receiving plant shall be notified in writing if the cataphoretic dip coating materials are changed following sampling with regard to binder / solids ratio, or if measures are taken which might impact on the flow.
2.9Overpaintability
The coating shall be capable of being repaired using state-of-the-art touch-up paints without disturbing surface changes such as crinkling. The paints to be used shall be agreed with the receiving plant and shall be matched to the relevant paint structure. Also refer to Section 4.20 of this DBL in this respect.
2.10Repair paintwork
For repair paintwork, the supplier's repair instructions and the coating materials used shall be indicated according to 2.1.2. If repair paintwork is carried out, the relevant components shall also comply with the requirements of the specified PV. The relevant department is responsible for requesting a component repaired in line with these instructions and for testing it according to the specified PV.
The following process is required by MBC for rewelded, cataphoretically coated components:
Completely remove any weld residues from the weld.
- Use angle grinder to remove weld flash.
- Resand using 80 grit sanding paper.
- Clean using commercially available silicone remover.
- Apply 2-component repair primer 4075 manufactured by Spies Hecker.
Mixing ratio, layer thickness and drying according to manufacturer's specifications.
Refinish using MB 7 167, MB spray can (1-component) MB Art. No. 00 986 29 50/7 167
2 spray applications, air drying.
3Dimensions and tolerances / Form of supply
In accordance with drawing and approved sample.
4Technical data
Preliminary remark:
Since in addition to the quality of the coating material itself, the material, the pretreatment and the shape of the parts to be coated may also be crucial to compliance with the following requirements, the tests shall be conducted on finished parts.  If, due to their size, components are sawn into pieces, the
cut edges shall be protected (by waxing, masking with Jaband No. 92402 supplied by Jaband, www.jaband.de).
A test angle between 30° and 70° shall be maintained. For components intended for the underfloor, the underside of the components in the intended installation position in the vehicle shall form the upper side in the test chamber.
All values indicated are maximum values.
FPT ... Focal point test, refer to Section 6.2 of this DBL.
From Section 4.8, either cross cuts or scratch tests can be performed. The values indicated shall apply in each case.

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