SAE-AMS-W-6858
ADOPTION NOTICE
SAE-AMS-W-6858, "WELDING, RESISTANCE: SPOT AND SEAM", was
adopted on 05-AUG-99 for use by the Department of Defense
(DoD). Proposed changes by DoD activities must be submitted to
the DoD Adopting Activity: ASC/ENOI, Building 560, 2530 Loop Road West, Wright-Patterson AFB, OH 45433-7101. Copies of this document may be purchased from the Society of Automotive
Engineers 400 Commonwealth Drive Warrendale, Pennsylvania, United
___________________
States, 15096-0001. https://www.wendangku.net/doc/3311209160.html,/
Custodians:Adopting Activity:
Army - MR
Air Force - 11
Navy - AS
Air Force - 11
AREA THJM
DISTRIBUTION STATEMENT A:Approved for public release; distribution is unlimited.
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1.2Classification:
Classification is based on function and use of the welded joint, rather than certain average levels of strength. Therefore, reliability is the key underlying quality distinguishing the work for each class.
The criteria described herein are intended to prevent larger variations in weld strength and quality than are compatible with the intended use.
Class A A welded joint, whose failure during any operating condition would cause loss of the equipment or system or one or its major components, loss of control, unintentional
release or inability to release any armament score, failure of gun installation
components; or which may cause significant injury to occupants of manned systems.
Class B A welded joint whose failure would reduce the overall strength of the equipment or system or preclude the intended functioning or use of equipment.
Class C A welded joint which is considered non-critical and for which no stress analysis is considered.
1.2.1The classification of welds in foil thickness is limited to Class A and Class C.
2.APPLICABLE DOCUMENTS:
The following documents of the issue in effect on date of invitation for bids, or request for proposal, form a part of this specification.
2.1American Welding Society (AWS) Publications:
Available from American Welding Society Inc., 2501 N.W. 7th Street, Miami, Florida 33125)
AWS A3.0Terms and Definitions
AWS C1.1Recommended Practices for Resistance Welding
3.REQUIREMENTS:
3.1Design requirements:
3.1.1Definition of terms used in this specification shall be in accordance with AWS A3.0, and as shown
in 6.2 herein.
3.1.2The class of welding shall be designated on the item specification or drawing. The design of Class
A resistance welded joints shall require the specific approval of the procuring activity who may
approve if satisfactory resistance welded prototypes exist, or upon evidence of the adequacy of the design and pattern of spot welding or upon the satisfactory performance of suitable static and
repeated loading testing of the design or applicable prototype.--` , , , , , ` ` ` ` ` , , ` ` ` ` ` ` , , , ` , , ` ` ` , -` -` , , ` , , ` , ` , , ` ---
3.1.3
There shall be two methods of certification for spot welds. The Standard Certification method shall be for a weld schedule that certifies that the requirements of Tables I through III or IV, and all other applicable weld property requirements have been met. The Design Allowable Certification method shall be a weld schedule that certifies a guaranteed strength value has been met.
TABLE I. Shear strength requirements for spot weld sheet specimens
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TABLE I(SI)*. Shear strength requirements for spot weld sheet specimens
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TABLE II. Shear strength requirements for spot weld sheet specimens
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TABLE II(SI)*. Shear strength requirements for spot weld sheet specimens
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TABLE III. Shear strength requirements for spot weld sheet specimens
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TABLE III(SI)*. Shear strength requirement for spot weld sheet specimens
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TABLE IV. Shear strength requirements for spot welds in foil
TABLE IV(SI). Shear strength requirements for spot welds in foil
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3.1.3.1The Design Allowable Certification method is intended to routinely permit the design and use of
smaller welds where the design stress permits and space or equipment or material conditions
compel; or to permit the design and use of stronger welds where they are wanted and the weld conditions are able to provide them. For a given joint a guaranteed strength value and weld
class must be specified on the drawing.
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3.1.3.2The provisions of the Design Allowable Certification method may be used to certify a weld
schedule when unusual conditions apply. For example, when welds are made through adhesives or through protective finishes or when it is desirable to use diffusion welds as integral
reinforcements to nuggets or in lieu of nuggets.
3.1.4When conditions are encountered which cause any of the requirements of this specification to be
inapplicable, the contractor shall submit alternate procedures and requirements for approval by the procuring activity. The request for approval shall include a description of the conditions which
render the requirements inapplicable, such as reduced flange widths and space limitations; and shall include data to indicate that the alternate procedures and requirements are adequate for the given application.
3.1.
4.1Granted approvals of alternate procedures shall remain in effect as complying with this
specification until the contractor is notified otherwise by the procuring activity.
3.2Materials and methods of preparation:
3.2.1Material combinations:
3.2.1.1Combinations not requiring specific approval: The metals listed below may be welded in any
combination within each lettered grouping.
a.Aluminum and its alloys
b.Magnesium and its alloys
c.Titanium and its alloys
d.Plain carbon steels of less than 0.15 percent carbon
e.Austenitic steels; precipitation hardening steels; nickel and cobalt base alloys.
3.2.1.2Combinations requiring approval: Use of the following metals requires specific approval of the
procuring activity: Clad 7075 aluminum alloy in thicknesses less than 0.020 inch or 0.51
millimeter (mm); any aluminum alloy in the 2000 or 7000 series which is unclad; or any
magnesium alloy which will be exposed to accelerating corrosion conditions like a marine
environment.
3.2.1.3Special requirements: Metal combinations not included in 3.2.1.1 shall require the following
establishment of weld ductility. The average tensile (normal to spot plane) strength of twenty spot welded specimens shall be greater than 0.25 times the minimum average shear strength in
Tables I through IV applicable to the subject alloy or as established for the Design Allowable
Certification. This test may be conducted on specimens, as welded, or after subsequent heat
treatment. Heat treatment is a later manufacturing operation and not the post weld current
provided through welder electrodes. The production process shall specify the certified weld
schedule plus the subsequent heat treatment used to demonstrate the weld ductility required
herein.
3.2.2Surface conditions: The surface of the parts to be welded shall be free from objectionable films
such as heavy oxides, scale, ink, grease, dirt, or other substances or surface conditions
detrimental to the welding process.
3.2.2.1Group I materials:
3.2.2.1.1Oxide coatings may be removed by mechanical treatment (such as sanding or wire brushing)
or by chemical treatment.
3.2.2.1.2The ability of a cleaning procedure to effectively prepare Group I materials for welding shall be
demonstrated by ability of materials cleaned by the process to be welded in compliance with
the Certification requirements of this specification. The cleaning procedure is a necessary
component of the Certification weld schedule.
3.2.2.1.3Conformity of test and production materials surfaces to those produced by the normal cleaning
procedure shall be checked by surface resistance readings. Maximum values for test and
production materials shall be established as indications of the conformity required for welding
in compliance with this specification.
3.2.2.1.4The minimum and maximum time span that is permitted between parts cleaning and parts
welding shall be established by the contractor. The contractor shall demonstrate that no
deterioration of surface conditions take place during typical holding or storage conditions
during that span. Deterioration shall be excessive when high values lead to inability to meet
Certification requirements. Conditions and limitations may be applied generally as to a
standard process, or specifically as to an exceptional assembly or material combination where
warranted.
3.2.2.1.5When a cleaning procedure is changed, if the contractor can demonstrate that the new
procedure produces the same results as the old procedure, recertification of weld schedules
shall not be required. This conformity will be shown by (1) producing the same weld results as
made during Qualification tests (with Certification quantities) with a weld heat change within
±10 percent of the established value and (2) showing a surface resistance average that is no
more than 1.05 times that achieved by the replaced procedure.
3.2.2.1.6Coatings which improve the corrosion resistance or sealing characteristics without affecting the
weld properties may be applied prior to welding. Such finishes must be considered as final
steps of the cleaning procedure and necessary conditions specified on the Certified weld
schedule.
3.2.3Joint thickness: Joint thicknesses are only limited to those thicknesses or combination of
thicknesses on which Certification weld schedule can be established and production parts can be made to meet the production requirements of this specification.
3.2.4Fitup: Mating parts assembled for welding shall be designed and processed to fit so that before the
first and each successive weld is made the surfaces to be joined by the weld are in contact with each other or can be made to contact each other with manual pressure.
3.3Equipment requirements:
3.3.1Welding machines: The welding machine shall consist of a suitable source of electrical energy,
means of adequately cooling the electrodes, and a means of reliably controlling and indicating the relative magnitude of the current, the welding force, and the time of current flow; to fulfill the
requirements specified herein. The force and current controls shall operate so that no current can flow until the welding force is applied by the welding electrodes. It shall not be possible to reduce electrode force before current is terminated.
3.3.2Electrodes: Suitable electrode material and shapes shall be used to perform welding in
conformance with this specification.
3.3.3Shear testing machines: The contractor shall provide spot weld shear testing machines as
required. All shear testing machines shall be accurate within ±2 percent of the indicated reading.
Portable spot weld shear test machines shall be checked for accuracy at intervals not to exceed 2 months.
3.3.4Surface resistance indicators: The contractor shall provide one or more surface resistance
indicators for checking the effectiveness of cleaning solutions and procedures engaged in
preparing Group I metals for spot welding. Surface resistance indicators shall be checked for
accuracy and recalibrated as necessary.
3.3.5Jigs and fixtures: All tooling that is required to locate welds or assist in the assembly of welded
parts that passes through the magnetic field during the molding operation, shall be made of
nonmagnetic materials insofar as possible. Jigs and fixtures must be so designed that no welding current can shunt through them instead of passing through the work pieces.
3.3.6Maintenance of equipment: Unless otherwise specified, each item of equipment shall be inspected
periodically as recommended by the manufacturer. Adequate preventative maintenance shall be furnished. Defective equipment parts affecting machine operation shall be replaced before
production welding is resumed.
3.4Qualification of welding machines:
3.4.1Qualification approval: Qualification is performed on a distinctive resistance spot or seam welding
machine to determine the ability and consistency of operation of a machine type at a facility.
Qualification has as a purpose to identify and verify the range of welding that a facility may, for
contractual purposes, be considered capable. To have his equipment qualified and approved for use the contractor shall perform the tests specified herein under the surveillance of the procuring activity. Weld conditions shall be documented on a Machine Qualification Test Report. Typical examples of report forms are given in AWS C1.1. Such forms may be modified or expanded as required. Weld conditions and test results shall be submitted with an application for approval to the --`,,,,,`````,,``````,,,`,,```,-`-`,,`,,`,`,,`---
procuring activity. After approval is indicated, these reports shall be posted near the machine so as to be available to contractor operators and inspectors, and agents of the procuring activity.
3.4.1.1Qualification by one procuring activity of the Department of Defense shall be Qualification for all
DOD procuring activities and for those other governmental agencies who elect to subscribe to
this specification.
3.4.2Machine qualification scope: Machines shall be qualified to meet the weld requirements for the
highest classification in a metal group for which it is intended to be used in production. A machine qualified to weld to the requirements of one weld classification in a group shall be automatically considered qualified for lower weld classifications. When one machine of a distinctive type in a plant site passes the Qualification tests all other machines of the same type shall be considered qualified. Machines used for Class C foil welding are qualified just by establishing a weld schedule Certification. Machines qualified to a class for seam welding shall be considered qualified for roll spot welding to the same class.
3.4.2.1Types of equipment: Distinctive types of equipment must include those differing in any of the
following respects:
a.Manufacturer of machine
b.Manufacturer of control panel
c.Type of machine, or model number
d.Electrical rating or capacity
e.Type of electrical energy
f.Type of pressure application.
3.4.2.2Test conduct: No maintenance work and no control adjustments are permitted during the welding
of a set of test specimens.
3.4.2.3Test materials: The test materials for a Group I Qualification shall be any aluminum alloy
commonly used in resistance welded products. For Groups 2 and 3 qualification test material
shall be any steel commonly used in resistance welded products.
3.4.2.4
Combination selection: For each group of alloys, two test sets shall be required. One at the highest, one at the lowest end of the range for which the Qualification is desired. This normally means that the thickest to thickest metal combination on one end and the thinnest to thinnest on the other end.
3.4.2.4.1
Except that when a Qualification is achieved on one combination of foil thicknesses, the equipment shall be considered qualified for all thicker foils welded to foils.
3.4.2.5Test specimen requirements: Weld test and examination requirements are shown in Table V.3.4.2.6
Weld machine requalification: When the equipment has once been qualified, it need not be
requalified for other contracts or production lots. A change of location within a plant, not involving a change in power source, or maintenance, or parts replacement does not necessitate requalification. Requalification shall be required if the machine is rebuilt or if significant
operational changes are made in it. Existing machine Qualifications made under superseded revision of this specification shall be honored.
3.5Weld schedule certification:
3.5.1
Certification: Tests shall he conducted to determine if a particular machine, in combination with a specific weld schedule and other specific conditions, will produce on a given set of materials
resistance welds that conform to the requirements of specification. Documentation of these tests will be contained in a completed Certification Test Report that will be available to agents of the procuring activity. In addition, the weld schedule shall be posted near the machine and be available to machine operators, inspectors, and agents of the procuring activity.
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TABLE V. Machine qualification test specimen requirements
3.5.2
Certification test reports: For each machine and each combination of relevant conditions (such as alloy, temper, surface conditions, and thickness combinations), the contractor will determine the effective weld machine settings for test and production parts. The schedule of conditions and parameters shall be formally entered on a report form before the test welding. Typical examples of report forms are given in AWS Cl.l. These shall be modified or expanded as required. After acceptance, production setups shall be made to the schedule therein given, with the scheduled latitude of 4.2.6 allowed.
3.5.2.1
Examination data: Part of a completed Certification test report shall be the shear strength data on each weld, the average, the numbers of specimens with shear values outside of the set limits, and the nugget diameters of each metallographic specimen. The examination page will have a formal indication of the success or failure to meet the Certification criteria applicable to the subject material combination.
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3.5.3Test vs. production conditions: It is the purpose of Certification to show the results that can be
expected on production parts. It is necessary then to produce a correspondence between test
conditions and production conditions. The material conditions (3.5.2) must be replicated in parts and material for weld tests. Any other production condition known to be relevant must be part of the test. These include, for example, curvature of the parts, mandrels in lieu of electrodes, large magnetic tools lying in the weld machine throat, narrow edge distances, offset or shaped
electrodes tips, time spans (minimum and maximum) between final preparation and welding, initial and final surface preparations, and close spot spacing. A test of relevancy may be that the
average nugget diameters in the part will equal the average Certification nugget diameters when produced by any machine weld heat seetings not further than 10 percent from the Certification heat settings.
3.5.4Certification test specimen configuration and examination requirements: Tests shall be as
specified in Tables VI Through IX and as shown in Figures 1 through 6.
TABLE VI. Certification specimen and examination requirements
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TABLE VII. Certification specimen and examination requirements
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TABLE VIII. Certification specimen and examination requirements