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Mercedes-Benz MBN 10347

Company standard Date published: 2018-02
Transition period: 0 months
Total no. of pages (including annexes): 19
Person in charge: Peter Horn
Email: peter.p.horn@daimler.com
Plant: 059; Dept.: RD/RBE
Date of translation: 2018-02 Phone: +49 (0)176 30925760

Testing of steel weld stud fasteners

Observe approval of procurement sources

Foreword

The testing of weld studs is intended to ensure the quality of the weld studs during the ongoing process.
The strength is monitored to check the welding parameters set and to verify the reliability of the process.
If the process includes other quality assurance measures intended to verify the reliability of the process,
the continuous testing of the weld studs may be waived.

This edition supersedes the former edition of this Standard.

Application note:
In line with the scope of application, the usage of the present version of this company standard shall be
checked in case of new vehicle projects or components for which no concept/basic specifications or
component requirement specifications have yet been approved at the date of issue of this version.
The respective contract documents regulate the mandatory application of the present version of this
company standard by the supplier.

Changes
In comparison with edition 2011-06, the following changes have been made:

- Complete editorial revision (including transfer to current template).

- Table 4 Ground stud ring flange base
- Section 7.4.1 Inclined stud position added
- Section 12.1, section 12.2 and section 12.3 outsourced in BQF 10347

Note: This translation is for information purpose only.

The German version shall prevail above all others.

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Contents

1 Scope of application...............................................................................................................2
2 Normative references.............................................................................................................3
3 Terms and definitions.............................................................................................................3
4 General requirements ............................................................................................................4
5 Specified suppliers and approval of procurement sources ....................................................4
6 Non-binding illustration of product groups .............................................................................5
7 Non-destructive testing ..........................................................................................................6
7.1 Description of process sequence ...........................................................................................6
7.2 Inspection process .................................................................................................................6
7.3 Test documentation ...............................................................................................................6
7.4 Assessment criteria................................................................................................................6
7.5 Flange height measurement ..................................................................................................9
7.6 Coarse-pitch thread / metric studs .......................................................................................11
7.7 P-stud...................................................................................................................................11
7.8 Ground stud .........................................................................................................................12
7.9 Buckling torque wrench........................................................................................................14
8 Destructive strength test ......................................................................................................16
9 Test documentation .............................................................................................................16
10 Corrective actions ................................................................................................................16
11 Test values for the relevant test tools and stud types ..........................................................16
12 Test tools .............................................................................................................................18
Annex A (informative) General ...................................................................................................................19
A.1 Further specifications / literature ..........................................................................................19

1 Scope of application

This Standard applies to all weld stud fasteners (steel design) welded using the drawn arc stud welding
process; refer to MBN 10372. Pressure joining method by welding to be tested in accordance with MBN
10346.
The installed condition of the weld stud fasteners in the finished vehicle is described, as required by
Development. The relevant departments are responsible for implementing this test.

Tests for process assurance shall be performed by Manufacturing. In the case of quality problems, the
departments responsible may take additional random samples. The destructive test shall be used within
the framework of special tests for system approval and in case of quality issues. For product groups which
are not described in this Standard, refer to MBN 10351, MBN 10389, MBN 10390, MBN 10407 and MBN
10414.

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2 Normative references
The following referenced documents are necessary for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.

MBN 10346 Testing of Weld Nut and Weld Screw Fasteners

MBN 10351 Guideline for Aluminum Arc Welding Studs into Aluminum Parts

MBN 10389 Steel Arc Welding for Welding Fasteners into Steel Parts

MBN 10390 Engineering Standard for Round Weld Nuts Using the Drawn-Arc Welding
Process on Steel Parts
MBN 10372 Standard for Steel Arc Welding Studs into Steel Parts Using Drawn-Arc
Ignition
MBN 10407 Testing of Aluminum Weld Stud Fasteners
MBN 10414 Testing of Arc Welding Brackets

3 Terms and definitions

KTO Klein-Teile-Optimierung (small parts optimization – fastener technology)

Bond weld: Is an incompletely melted weld where the weld nut/screw fastener only sticks to
the metal part and does not have the required strength.

Stud type M6x21 F9,4 Weld stud with metric nominal thread diameter of 6mm, length 21mm and flange
diameter 9.4mm.

KTO: Klein-Teile-Optimierung (small parts optimization)

LF: Large flange

T6: Coarse-pitch thread ∅ 6 mm

M8: Metric thread M8

T-stud: (old designation) Stud without thread which represents a "T" in section

P-stud: (new designation) Mushroom head stud without thread

RF: Ring Flange

VF: Full Flange

F9,4: Flange diameter 9.4mm

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4 General requirements

To guarantee product safety and product quality, and to comply with homologation requirements, all
relevant statutory regulations and laws shall be complied with. In addition, the relevant requirements of the
Daimler Group apply.

All materials, process technologies, component parts, and systems must conform to the current statutory
requirements regarding regulated substances and recyclability.

5 Specified suppliers and approval of procurement sources

Approved manufacturers/suppliers are documented with binding effect in BQF (Approval of Procurement
Sources) 10347 Testing of Weld Stud Fasteners.
This BQF can be accessed internally using the DocMaster system. External units should contact the
person in charge of this Standard.

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6 Non-binding illustration of product groups

Parts not illustrated here can be accessed in the KTO catalog, see Annex A1 and Figure 1.

P-stud
with/without ring flange RF
Ground stud Centering stud
and large flange LF
with/without nut without threads
(was T-stud)

T6 VF
Standard Coarse-pitch thread stud Coarse-pitch thread stud
Coarse-pitch Large flange T5 VF9 mm Large flange
thread stud T5 LF13 mm
T6 VF

Metric paint Metric paint groove stud Metric paint groove stud
groove stud Large flange RF Large flange VF 13 / 14 mm

Coarse-pitch Metric Coarse-pitch

thread LF 13 and RF 9 thread
RF 9mm Ring flange LF 13 and RF9
Ring flange Ring flange

Fig. 1: Illustration of product groups

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7 Non-destructive testing

7.1 Description of process sequence

Each faulty weld ascertained through parameter monitoring (e.g. marked in color) shall be examined.
Additional test specimens shall be removed from ongoing production in specified random samples. For the
weld studs to be tested, refer to the relevant stud schedule; test frequencies are specified by the testing
department, e.g. depending on the incidence of failure (dynamic sample).
Non-destructive testing shall be performed in the form of a visual inspection.

7.2 Inspection process

The visual inspection shall be performed in accordance with the assessment criteria listed in Table 1. The
inspection shall be performed by trained personnel at a sufficient distance of observation and with good
illumination.

7.3 Test documentation

The failure incidence shall be documented by means of a suitable instrument so that permanent tracking
is possible, e.g. using a stud database.
Recognized failures such as bond welds shall result in immediate correction of the system or welding
equipment.

7.4 Assessment criteria

The weld studs shall be assessed visually in accordance with Table 1.

Table 1: Assessment criteria

Assessment Corrective
No. Example
criterion action

Reset missing stud.

1 Stud missing
Check system/equipment.

a Straighten stud, if
a  approx. 5°,
P-stud: a  5°,
(for T-stud 10°)
Stud
2 otherwise remove stud,
incorrectly set clean surface,
- set new stud, check weld
equipment.
Testing the inclined stud
position, see section 7.4.1

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Stud
Check tool and current.
damaged and
Remove stud,
3 soiled
clean surface,
(weld spatter and damaged
set new stud
thread)

Bond weld Remove stud,

4 Air visible between stud clean surface,
and metal sheet set new stud

Weld flash protruding too Check tool and current,

far: remove protrusion if it
B = flange Ø + ≤2.5mm interferes with the
5 H = flange height + assembly of following
≤2.5mm components
Not for studs with large Weld flash largely depends
flange LF on application

Flange height for studs Check whether safe

with large flange and/or assembly is possible; if
ring flange necessary, remove stud
and set new stud.
Tolerance: h Large flange
6 hGroßflansch Flange height test:
hLarge flange: X – 0.3mm
X Determining the smallest
For M8RF LF18:X-0.4mm X and largest value of the
total flange circumference
is necessary for
X = depends on stud assessment.

D2 Non-binding information:

D1 D2 L3

Underhead dimension: 3.0 5.0 3.6 ± 0.3

- P-stud (new designation) L3

5.0 9.0 7.3 ± 0.2
Measurement after

7 - T-stud (previous
designation)
D1
welding

P6x11.5, RF9, LF13:

flange height 2.3-03mm,
see 3D data

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Note on no. 7:
Note that the height measured on the body-in-white may vary depending on the paint coat. This
shall be taken into account accordingly in the fastener. The specifications of the 2D/3D data records of the
P-studs are binding.
Dimension L3 after welding including tolerances (0-point) is contained in the data records (2D/3D data)
and binding.

7.4.1 Inclined stud position

If after a visual inspection it is established that the welded stud with large flange is inclined, the stud at
flange height according to Table 1 shall be inspected to be sure that the specified permitted inclined
position is not exceeded.
The flange height shall be determined with the flange height measuring device according to section 7.5,
i.e. the entire flange shall be measured. Turn the testing device on the flange and hold at the highest
dimension, then measure on the opposite side at the lowest dimension.
If both dimensions are within the flange height tolerance specified, it can be assumed that the maximum
inclined stud position according to Table 1 has not been exceeded.
In Figure 2 this is displayed on the example of a ring flange stud with large flange (diameter 18 mm) and a
flange height of 4.0 -0.5 mm, meaning that if the flange height tolerance in the welding process is fully used,
the stud is inclined at a maximum of 2 degrees.

Figure 2: Sketch of an inclined stud in relation to flange height

For a stud without flange, the inclined position can be checked, e.g. by measuring the angle.

7.4.2 Incline for ground studs

An inclined position of ground studs can also be checked by measuring the flange height. However to do
this, the screwed-on nut, if present, shall be unscrewed and screwed back on after the flange height is
measured; for the tightening torque of the nut before painting and after testing, refer to Table 3. Further
requirements can be found in the 2D/3D data.

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7.5 Flange height measurement

7.5.1 General description

The flange height measuring unit MP 015… supplied by the manufacturer listed in BQF 10347, is suitable
for measuring the flange height of welded-on studs up to dia. 6F14, see Figure 3.

Fig. 3: Flange height measuring unit MP 015…

7.5.2 Presetting of flange height measuring unit

To preset the flange height measuring unit, please proceed as follows:

 Position the flange height measuring unit on the setting gage, see Figure 4.

 Then set the scale of the measuring unit to zero or to the desired value by rotating, see Figure 5

Figure 4: Positioning Figure 5: Setting

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7.5.3 Inspection process with flange height measuring unit

To measure the weld stud flange, please proceed as follows:

 Position flange height measuring unit on the stud ensuring proper contact and angularity (see Figure
6).
 The smallest and largest value shall be determined across the entire flange circumference.
 Read the value measured on the scale of the dial indicator (see Figure 7).
Flange height

Figure 6: Positioning Figure 7: Reading value

7.5.4 Flange height after welding

The flange height as per MBN 10372 shall be tested after welding.
Underhead dimension P-stud see Table 1, no. 7.

Table 2: Non-binding flange height after welding

Flange height X
(for tolerance, see Table 1)
Stud
Name Large flange Large Large
Large flange ∅
flange ∅ 9.4 flange ∅
∅ 9 mm 18 mm
mm 13/14 mm
T5 2.3 - 3.3 -
T5 RF9 2.3 - - -
T6 2.3 - 3.3 -
T6 RF9 2.3 - - -
M6 RF9 - - 3.3 -
M6 - 2.3 3.3 -
M8 RF - - - 4.0
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The specifications of the 2D/3D data records of the relevant weld studs are binding; also refer to MBN
10372. Deviations are possible, however they shall be agreed with the person in charge.

7.6 Coarse-pitch thread / metric studs

In the combined tensile/torque test (torsion test), a tensile force acts upon the joining zone as the result of
a rotating movement; place the required torque wrench on top depending on the weld stud diameter. The
permitted load is preset and cannot be influenced by the operator. Place the test wrench with the relevant
sleeve vertically on the stud to be tested and activate the start button. If the stud shears or tears off in the
joining zone (without tear-out in the metal sheet) before the screwdriver is stopped automatically, the
strength is insufficient. The weld setting shall be corrected, see Figure 8.

Sleeve

Plate Stud

Fig. 8: Test tool on stud

7.7 P-stud

The tensile test shall be performed using a special tool (extractor with torque wrench). The extractor is
used to apply a tensile force to the stud with a defined torque. For this purpose, push the extractor onto
the P-stud and turn the handle until the clutch slips when the set torque is reached. During the tensile
test, ensure that the extractor does not tilt. Before removing the extractor, relieve the torque. If the stud
shears or tears off in the joining zone (without tear-out in the metal sheet) the strength is insufficient. The
weld setting shall be corrected, see Figure 9.

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Fig. 9: Illustration of tensile test P-stud

7.8 Ground stud

7.8.1 Ground stud without octagonal flange

To test ground studs without octagonal flange, load the existing nut using a torque wrench.
If the stud shears or tears off in the joining zone (without tear-out in the metal sheet) the strength is
insufficient. The weld setting shall be corrected.

After testing, always undo the nut and preload with the torque specified in Table 3, to ensure paint
tightness and so that the nut can be undone later.

7.8.2 Ground stud with octagonal flange

7.8.2.1 General description

The stud testing tool SMB019 shall only be used for testing ground studs with octagonal flange; see
Figure 10.

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Fig. 10: Stud testing tool SMB 019

7.8.2.2 Using the stud testing tool

To test the ground stud, please proceed as follows:

 Open the clamping bracket of the stud testing tool and place the tool on the ground stud, see Figure
11.
 Close the clamping bracket of the stud testing tool and push the sleeve downwards; see Figure 12.
 Then turn the sleeve, so that the body is lifted off the weld flash and pulled onto the octagonal flange
of the ground stud; see Figure 13.
 Figure 14 illustrates the starting position for testing the ground stud.
 Place a suitable socket wrench on the hexagonal flange of the stud testing tool and check the
grounding stud using a commercially available torque wrench; see Table 3.

Figure 11: Opening Figure 12: Positioning Figure 13: Turning Figure 14: Starting
position

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7.9 Buckling torque wrench

The non-destructive testing method using the buckling torque wrench is suitable for the examination of
centering stud weld joints and M8 with ring flange, see Figure 15.
The buckling torque shall be set to the stud under test; see Table 3.

Setting to relevant stud diameter:

 Pull knob out of handle.

 Turn the handle to set the required buckling torque. Read the set value on the scale.

 Push knob back into handle.

Fig. 15: Buckling torque wrench

7.9.1 Application of head of buckling torque wrench

The diameter of the mounting bore in the test tool head shall always be matched to the stud diameter.
The head of the stud testing tool shall be placed firmly on the stud to be tested, see Figure 16 and Figure
17.

Correct Incorrect Incorrect

Head too large Head not resting correctly

Fig. 16: Application of head of buckling torque wrench on stud

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7.9.2 Buckling torque wrench for centering studs 6 and 8

Insert for stud

Fig. 17: Buckling torque wrench for centering stud

7.9.3 Application of buckling torque wrench

Move the lever of the stud testing tool as illustrated in Figure 18. The buckling torque wrench shall only be
operated in the direction of the green marking.

Operation as illustrated in Figure 19 may result in damage to the tool and stud.
Correct Incorrect

Fig. 18: Correct application Fig. 19: Incorrect application

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8 Destructive strength test

Tear the stud from the metal sheet using suitable equipment. The pull-out or fracture pattern shall be
assessed by trained personnel.

9 Test documentation

The test results of the random sample shall be recorded on the control cards included with the test plan.
The random sample test results shall be archived for the relevant period of retention.

10 Corrective actions

If a failure is recognized during testing, this failure shall be corrected immediately according to the
specifications. The relevant system shall also be checked/corrected if required. In addition, suitable action
shall be taken to deal with faulty bodies. A torsion test shall be performed on the reset stud.
For specifications on rework, contact the department responsible.

Special case ground weld studs

Due to their relatively large diameter, ground studs may be reworked with MAG weld. The MAG weld shall
only bear against the flange, and the temperature stress on the stud shall be kept as low as possible.
For specifications on rework, contact the department responsible.

Note:
Following welding, always undo the nut and preload with the torque specified in Table 3 to ensure paint
tightness and so that the nut can be undone later.

11 Test values for the relevant test tools and stud types

The weld stud length can be disregarded with regard to torque specifications, as the strength properties
are primarily determined by the cross-section.

The following specifications only refer to weld joints with the material steel and applications in accordance
with MBN 10372.

In the event of deviating applications, deviating test values may become necessary. Such deviating test
values are not considered in this Standard. Deviating test values shall be checked by the responsible
departments and documented separately. This may be done, for example, in a similar way to the
documentation of tightening torques for threaded connections (bolts with nuts) with regard to the nut to be
installed in the parts list (dialog) or drawing.

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Table 3: Test tools with test values

Ø[mm] Stud type Test tool Test value

2.6/3.0 0.6 Nm ± 10%

P-weld stud (was T-
Manual torque wrench
5.0 stud) 2.5 Nm ± 10%

7.0 P7x10 RF9 Buckling torque wrench 3.0 Nm ± 10%

6.0 4.0 Nm ± 10%
Centering stud Buckling torque wrench
8.0 6.0 NM ± 10%

Coarse-pitch thread
5.0 stud (Xmas tree stud, Battery-operated screwdriver 4.0 Nm ± 10%
VF)

Coarse-pitch thread
5.0/6.0 Battery-operated screwdriver 4.0 Nm ± 10%
stud ring flange

Paint groove stud

6.0 Battery-operated screwdriver 7.0 Nm ± 10%
metric (VF, RF)

Paint groove stud ZE340 16.0 Nm ± 10%

Buckling torque wrench
metric with RF PSC950 36.0 Nm ± 10%
8.0
Paint groove stud
Battery-operated screwdriver 22.0 NM ± 10%
metric with VF

12.0 Nm ± 10%
Manual torque wrench SW 10
6.0 Ground stud - M6 (IET bearing) Pre-tightening torque after
Testing via nut. testing:
4.0 -1.0 Nm
Ground stud –M6 Manual torque wrench SW 10 with
6.0 with octagonal flange SMB 019.00.65 (M 065 341) 12 Nm ± 10%
Testing via octagonal flange.
22.0 Nm ± 10%
Manual torque wrench SW 11
Ground stud - M8 Tightening torque after
8.0 (IET bearing)
Testing via nut. Test:
6.0 -1.0 Nm
Ground stud - M8 Manual torque wrench SW 13 with
8.0 with octagonal flange SMB 019.00.64 ( M 065 337) 22.0 Nm ± 10%
Testing via octagon.

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12 Test tools

The testing department is responsible for selecting the test tools to be used.

The screwdrivers used shall not be pulse screwdrivers and shall correspond to the following specification:

- Torque tolerance of  10% in test range

- Visual display of test result

All order numbers and testing tools of the manufacturer can be found in BQF 10347.

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Annex A (informative)

General

A.1 Further specifications / literature

BQF 10347 Testing of Weld Stud Fasteners

KTO catalog: Internal: http://kto.app.corpintra.net

External: https://engineering.supplier.daimler.com

KTO-DOC 10002 Stud Type List

KTO-DOC 10042-2 External Tests for Small Parts Using the Drawn Arc Welding Method

KTO-DOC 10015 2D/3D Illustration of Weld Studs Using the Drawn Arc Welding Method

DIN EN ISO 14270 Resistance Welding – Destructive Testing of Welds – Specimen Dimensions and
Procedures for Mechanized Peel Testing Resistance Spot, Seam and Embossed
Projection Welds

DIN EN ISO 14272 Resistance Welding – Destructive Testing of Welds – Specimen Dimensions and
Procedures for Cross Tension Testing Resistance Spot and Embossed Projection
Welds

DIN EN ISO 14273 Resistance Welding – Destructive Testing of Welds – Specimen Dimensions and
Procedures for Shear Testing Resistance Spot and Embossed Projection Welds

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