1、AEROSPACEARP1675RECOMMENDED PRACTICEIssued 1990-10Reaffirmed 2014-08Structural Weldbondingof Aluminum StructuresRATIONALEARP1675 has been reaffirmed to comply with the SAE five-year review policy.1. SCOPE:1.1 This SAE Aerospace Recommended Practice describes the aluminum weldbondingprocess for fabri
2、cation of secondary aircraft structural assembliespossessing excellent strength, fatigue life, and environmental durability.1.2 The nature of the weld nugget, produced by resistance weldbonding, providesmlcrocrack initiators and propagators which compromise the fatigue life.Additional development wo
3、rk is required to validate this process for eachprimary aircraft structure.1.3 This manufacturing process has been developed and validated for highstrength bare aluminum alloys AMS-4037 and AMS-4045 within the thicknessgages of 0.020 to 0.125 In (0.51 to 3.48 mm). It 1s expected to beapplicable to o
4、ther bare aluminum alloys and tempers. The use o f thisprocess 1s not recommended for clad or mixed bare-clad alloy systems becauseof decreased environmental durability.1.4 The surface preparation system has been validated for use with 80C (176F)service temperature modified epoxy paste adhesive whic
5、h cures at120 to 125C (248 to 257F). The adhesive contains a radio-opaquesubstance, strontium chromate, which permits nondestructive examination forbondline voids by X-radiography.1.5 Safety - Hazardous Materials:While the materials, methods, applications, and processes described orreferenced 1n thi
6、s ARP may Involve the use of hazardous materials, this ARPdoes not address the hazards which may be involved in such use. I t is thesole responsibility of the user to ensure familiarity with the safe andproper use of any hazardous materials and to take necessary precautionarymeasures to ensure the h
7、ealth and safety of all personnel involved.SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report isentirely voluntary, and its applicability and suitability for any particular use, includi
8、ng any patent infringement arising therefrom, is the sole responsibility of the user.“SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments andsuggestions.Copyright 2014 SAE InternationalAl
9、l rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical,photocopying, recording, or otherwise, without the prior written permission of SAE.TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside U
10、SA and Canada) SAE values your input. To provide feedbackTel: +1 724-776970 (outside USA) on this Technical Report, please visitFax: 724-776-0790http:/www.sae.org/technical/standards/ARP1675Email: CustomerServicesae.org |_SAE WEB ADDRESS: http:/www.sae.orgSAE INTERNATIONAL ARP1675 Page 2 of 362. APP
11、LICABLE DOCUMENTS:The following publications form a part of this ARP to the extent specifiedherein. The latest issue of SAE publications shall apply. The applicableissue of other publications shall be the issue in effect on the date of thepurchase order.2.1 SAE Publications:Available from SAE, 400 C
12、ommonwealth Drive, Warrendale, PA 15096.AMS-3107 Primer, Adhesive, Corrosion-Inhibiting, For High DurabilityStructural Adhesive BondingAMS-3708 Adhesive, Epoxy Paste, for Structural Weldbond (For 80C (180F)Servi ceAMS-3755/2 Powder, Fumed Silicon Dioxide, Thickening Efficiency 90AMS-4035 Aluminum Al
13、loy Sheet and Plate, 4.4Cu - 1.5Mg - 0.60Mn(2024-0), AnnealedAMS-4037 Aluminum Alloy Sheet and Plate, 4.4Cu - 1.5Mg - 0.60Mn(2024; -T3 Flat Sheet, -T351 Plate), Solution Heat TreatedAMS-4045 Aluminum Alloy Sheet and Plate, 5.6Zn - 2.5Mg - 1.6Cu - 0.23Cr(7075; -T6 Sheet, -T651 Plate), Solution and Pr
14、ecipitationHeat Treated2 . 2 ASTM Publications:Available from ASTM, 1916 Race Street, Philadelphia, PA 19103-1187.ASTM B 117 - Salt Spray (Fog) Testing2.3 U.S. Government Publications:Available from Standardization Documents Order Desk, Building 4D, 700Robbins Avenue, Philadelphia, PA 19111-5094.2.3
15、.1 Military Specifications:MIL-H-6088 Heat Treatment of Aluminum AlloysMIL-W-6858 Welding, Resistance, Spot and SeamMIL-P-17667 Paper, Wrapping, Chemically Neutral (Non Corrosive)MIL-C-22751 Coating System, Epoxy Polyamide, Chemical and SolventResistant, Process for Application ofMIL-P-23377 Primer
16、Coating, Epoxy Polyamide, Chemical and SolventResi stantMIL-T-81533 Trichloroethane, 1,1,1 (Methyl Chloroform)Inhibited, Vapor Degreasing2.3.2 Military Standards:MIL-STD-453 - Inspection, RadiographicMIL-STD-860 - Fokker Ultrasonic Adhesive Bond TestSAE INTERNATIONAL ARP1675 Page 3 of 363. DESCRIPTI
17、ON OF THE PROCESS:3.1 Aluminum weldbonding is an assembly process wherein the detail parts arefixtured by resistance spotwelding through an epoxy paste adhesive withsubsequent oven curing to achieve the strength and fatigue life of theadhesive bonded structure.3.2 The nature of the weldbond process,
18、 which makes use o f a structural pasteadhesive to join two detail parts, causes air entrapment during the matingof the parts. The entrapped air results in voids in the cured adhesivebondline. Voids are minimized by close f i t up of the detail parts, controlof bondline thickness during adhesive app
19、lication, the sequencing ofspotwelds during the welding operation, the use of vent hole(s) in thecutout areas, and excess material around the peripheral trim lines.3.3 This ARP describes the different process phases which are critical forachieving acceptable quality. They are as follows:Cleaning pri
20、or to and following heat treatmentSolvent vapor degreaseAlkaline cleanDeoxidizeLow voltage anodizeAdhesive primer applicationAdhesive applicationAssemblyResistance spotweldAssembly cureAlodineSurface finish3.4 Anodizing at low voltage (1.6 V DC) produces a thin anodic oxide layer of300 to 800 Angstr
21、oms (300 x 1010to 800 x 1 0 10m) in thickness whichprovides a stable, weldable surface resistance suitable for adhesivebonding. The surfaces are weldable up to eight weeks after processing.Scanning electron microscopic measurements of anodic oxide thickness are notrequired.3.5 The process time const
22、raints are as follows:3.5.1 Paste adhesive should be applied to the primed parts within 120 h from thetime of anodizing and within 24 h following the adhesive primerapplication.3.5.2 The adherend faying surfaces should be mated within 1 h following adhesiveapplIcation.3.5.3 Welding should be perform
23、ed within 96 h after the mating of the panel.3.5.3.1 Provision has been made t o store the frozen mated assembly prior tospotwelding provided that the total adhesive out-time at not over 27C(81F) does not exceed 168 h.SAE INTERNATIONAL ARP1675 Page 4 of 363.6 Adequate process controls utilize wedge
24、crack extension and weld lap sheartest specimens. The wedge crack extension test requires exposure for1.0 h 0.1 t o 95 t o 100% relative humidity at 50C 1 (122eF 2).4. TECHNICAL REQUIREMENTS:4.1 This ARP details the facilities, equipment, materials, materials control,manufacturing process, and quali
25、ty assurance for weldbonding. Materials,other than those shown, should not be used in the fabrication of parts inaccordance with this process.4.2 Facilities:In planning a facility for accomplishing aluminum weldbonding, considerationshould be made f o r the flow of parts from the beginning of cleani
26、ng throughall processing operations and the assembly, resistance spotwelding, curing,and finishing of the structure.4.2.1 Subsequent to chemical processing and prior to the weld-through operation,all detail parts, test specimens, and assembled detail parts should bestored or assembled in an environm
27、entally controlled room. The controlledarea should be maintained within 18 to 25C (64 to 77F) with a maximumrelative humidity of 65%. Any process or operation which producesuncontrolled spray, dust, fumes, or particulate matter utilizingsilicones, waxes, or any material detrimental to adhesive bondi
28、ng shouldnot be conducted in the controlled area.4.2.2 The area should be maintained under a positive pressure differential atall times by continuously operating air handling systems. The pressure- differential, with the entries closed, should be +0.05 in (+1.3 mm) ofwater. The following conditions
29、should apply:4.2.2.1 Regular maintenance of filters.4.2.2.2 No eating in the area.4.2.2.3 No smoking in the area.4.2.2.4 Maintain records of temperature and humidity in the controlled area.4.2.2.5 Vehicles permitted in the controlled area must be nonpolluting inoperation, such as electrically or han
30、d propelled.4.3 Equipment:4.3.1 Chemical Processing and Bonding Equipment:4.3.1.1 Solvent Vapor Degrease Tank: Commercially available solvent vapordegrease tank should utilize metallic baskets with adequate separatorracks or aluminum finger racks. Parts should not contact one another.The rack should
31、 prevent part damage, ensure good vapor circulationaround all part surfaces, and provide efficient condensate drainage.The recommended solvent is MIL-T-81533 1,1,1 trichloroethane, orequivalent.SAE INTERNATIONAL ARP1675 Page 5 of 36Alkaline Cleaning Tank: Should be constructed of mild steel. The tan
32、kshall be provided with controlled heating and agitation of thesolution. The heater and recorder controller shall be capable ofheating the solution to 70C 5 (158F + 9).Deoxidizer Tank: Should be constructed of polyvinyl chloride (PVC),CPVC, polyethylene, Koroseal (see 10.1) rubber, or equivalent or
33、300series corrosion-resistant steel. If corrosion-resistant steel is used,means should be provided to ensure complete electrical isolation of theworkpiece from the tank. The tank should contain a means o f agitationeither by air or by circulation with a submerged impeller or circulationpump. The pum
34、p and filter housing should be made o f PVC o r CPVCmaterial with polypropylene filter cartridges capable of filtration of(15 xm) particulate matter.Anodizing Tank: Should be constructed from 300 series corrosion-resistant steel. Provisions should be made so that the tank iselectrically insulated fr
35、om the holding fixtures and the parts beingprocessed. The tank should be provided with air agitation andcontinuous filtration by means o f a pump and filter housing made o feither PVC or CPVC material with polypropylene filter cartridges. Theelectrical power supply for the anodizing operation should
36、 producedirect current with +5% ripple at full power output.Anodizing Racks: Should be constructed of aluminum alloy withsufficient strength to carry the loads and with adequate currentcarrying capacity. The racks should be sulfuric acid anodized andprimed with three cured coats of MIL-P-23377 epoxy
37、 polyamide primer,applied in accordance with MIL-C-22751. Titanium stud contact pointsshould be placed no farther apart than 1000 times the part thickness.For instance, a part 0.030 in (0.76 mm) thick should have contacts nofarther apart than 30 in (762 mm). Special titanium nuts, with a sharpcircul
38、ar edge on one face, should be used to provide electrical contactto the workpiece in the trim area. Angular relief on the edge providesrinse water accessibility to the dissimilar metal contact to prevent orminimize staining. The anodize rack should be inspected weekly fordamage t o the insulating co
39、ating.Rinse Equipment: Should consist of an overhead shroud astride theanodize rack to provide spray rinse upon rack withdrawal from thesolutions. Provision should be made for spray rinsing with tap water ordeionized water, separately or simultaneously.Drying Oven: A circulating-air oven, with recor
40、ding controllers, shouldbe capable of maintaining a set temperature within 5C (9F) in therange of 28 to 95C (100 to 203F).Curing Oven: The circulating-air oven, with recording controllers,should be capable of maintaining a set temperature within 5C (9F) inthe range of 38 to 150C (100 to 302F).SAE IN
41、TERNATIONAL ARP1675 Page 6 of 364.3.1.9 Storage Rack - Chemically Processed Parts: Weldbond anodlzed coatingsare fragile and require protection from contact with solids andliquids. The anodized parts and process control specimens should bestored in racks where the rack touches the part only on the e
42、dges andoutside the peripheral trim line. The racks should be mobile andenclosed to transport parts from the process line to the clean room.4.3.2 Welding Equipment:4.3.2.1 Welding Machine: The spotwelding machine should be a three-phasemachine equipped with a computer-type microprocessor welding con
43、trollercapable of cycle-by-cycle heat control. The machine should be capableof controlling the weld force within 10 lbf (44 N) of the set pointand should be capable of controlling the forge force within 50 lbf(222 N) of the set point. The force settings should be establishedusing a calibrated Dillon
44、 electrode force gage f o r each machinecertification Input. Weld schedules for use with a Pertronmicroprocessor controller are referenced in 10.1.4.3.2.2 Welding Electrodes: Should be water cooled RWMA, Group A, Class 1.4.3.2.3 Tensile Testing Machine: Should be capable of achieving an accuracy of2
45、% of the indicated scale reading.4.3.2.4 Shear Equipment: The bench shear for preparation of the 1 x 4 in(25 x 102 mm) production weld process control specimens (see Figure 2)from the processed 8 x 30 in (203 x 762 mm) test panels should have a blade length of not less than 12 in (305 mm) and be cap
46、able of shearingaluminum specimens up to 0.125 In (3.18 mm) in thickness.4.4 Tooling:Tools and fixtures used to locate details to be weldbonded should applypressure to all surfaces being bonded. Tooling required to locate welds orassist in weld-through assembly should be made from nonmagnetic materi
47、al andso designed that the welding current 1s not shunted through the tool.4.5 Materials:4.5.1 Adhesive System:4.5.1.1 Adhesive: Should be a one-part thermosetting, thixotropic, 90.0% 0.8epoxy resin paste meeting the requirements of AMS-3708. The fillers,3.0% 0.3 strontium chromate and 7.0% 0.5 fume
48、d silica in accordancewith AMS-3755/2, shall be homogeneously dispersed in the resin. Thecure temperature shall not exceed 125C 5 (257F 9). The adhesiveshall be certified as meeting the requirements of AMS-3708.SAE INTERNATIONAL ARP1675 Page 7 of 36SAE INTERNATIONAL ARP1675 Page 8 of 364.5.5 Miscell
49、aneous Materials: Should be as summarized 1n 10.5.4.5.6 Metals: Only bare aluminum alloys in accordance with drawing requirementsshould be weldbonded. Weldbond surface preparation should be 1naccordance with requirements specified herein and should be performedafter forming, and the chemical preparation steps prior to and followingthe heat treatment operation.4.5.6.1 All parts, including the wedge crack extension and the welding processcontrol specimens, that require heat treatment should be solve
