1、 ENGINEERING MATERIAL SPECIFICATION Date Action Revisions Rev 03 2015 10 30 A1/3/4 N Status No longer in use or replacements named G. Weber, NA 2005 02 03 Activated Para 3.0, 3.2, 3.4, 3.5, 3.7, 3.8 para 2.1, 3.0.1, 3.7.2, 3.8.1 3.8.9 title revised on 3.4 & 3.6 D. Drobnich 1999 12 08 Activated H. Ma
2、rtins, K. Yerdon Copyright 2015, Ford Global Technologies, LLC Page 1 of 4 PLATING, TIN/ZINC ALLOY, ELECTROPLATED, WSS-M1P95-A1/A3/A4 OVER FERROUS BASE METAL NOT TO BE USED FOR NEW DESIGN PLATING, TIN/ZINC ALLOY, ELECTROPLATED, WSS-M1P95-A2 OVER FERROUS BASE METAL 1. SCOPE These specifications defin
3、e the physical and chemical properties required of a neutral electroplated tin-zinc alloy and its associated hexavalent chromium free passivate in order to provide the requirements of corrosion resistance and electrical conductivity. All processes are free from hexavalent chromium, lead, and cadmium
4、 2. APPLICATION These specifications were released to provide corrosion protective and electrically conductive coatings over steel fasteners and small parts. These coatings are also suitable for fasteners that are formed during installation (e.g. blind rivets, blind anchor nuts) and small non-elect
5、rical components. 2.1 SERVICE TEMPERATURE Due to the low melting point of tin-zinc alloy (197 C), the maximum service temperature is 190 C. These coatings are not recommended for body-in-white parts, parts that will be subsequently electrocoated, or parts subjected to high service temperatures for e
6、xtended periods. 3. REQUIREMENTS 3.0 STANDARD REQUIREMENTS FOR PRODUCTION MATERIALS Material suppliers and part producers must conform to the Companys Standard Requirements for Production Materials (WSS-M99P1111-A). 3.0.1 Approved Applicator Quality Requirements Applicators must follow coating manuf
7、acturer procedures and recommendations for chemical usage, equipment, analysis and processing. 3.2 CHEMICAL COMPOSITION BY WEIGHT TIN ZINC 65 to 85% 15 to 35% ENGINEERING MATERIAL SPECIFICATION WSS-M1P95-A1/A2/A3/A4 Copyright 2015, Ford Global Technologies, LLC Page 2 of 4 3.3 PLATING THICKNESS (AST
8、M B 487) Plating thickness requirements represent minimum values and apply to all significant surfaces unless otherwise specified on the engineering drawing. A1 5 Micrometers A2 8 Micrometers A3 10 Micrometers A4 13 Micrometers 3.4 CORROSION RESISTANCE (SAE/USCAR-1, FLTM BI 123-02, ARL 18-0034) Afte
9、r completing the specified corrosion cycles, components plated to these specifications must meet the Corporate Standard for corrosion resistance. Thickness Designation Salt Spray Hours APG/APGE White Corrosion Red Corrosion 1% Red Rust Hours Hours Cycles A1 48 400 10 A2 48 500 20 A3 48 600 25 A4 48
10、700 30 3.5 CONDUCTIVITY Conductivity testing shall be run with production representative parts and finishes assembled in a manner that represents normal assembly practice. Testing shall be conducted using the Four Terminal Gold Contact measurement method and applying normal hand applied force. The t
11、otal resistance, including finish, shall be no greater than 1 milliohm. Any change to this requirement or approved sources requires concurrence of the Electrical Engineering Components group. 3.6 ADHESION (ASTM B 571) Adhesion of the electro-plate to the base metal must conform to the requirements o
12、f the following test methods per ASTM B 571 3.6.1 Grind Saw Test No lifting or peeling of the substrate is permitted following grind saw test. ENGINEERING MATERIAL SPECIFICATION WSS-M1P95-A1/A2/A3/A4 Copyright 2015, Ford Global Technologies, LLC Page 3 of 4 3.6.2 Burnishing Test No blistering, lifti
13、ng or peeling of the electroplate from the substrate is permitted following the burnishing test. 3.7 EMBRITTLEMENT (WSS-M99A3-A) Parts plated to these specifications shall be free from the detrimental effects of hydrogen embrittlement or other factors which result in part brittleness. All parts shal
14、l meet the requirements of WSS-M99A3-A except as noted. 3.7.1 If hydrogen embrittlement relief via heat treatment is required, post treatments will be performed after heat treatment. 3.7.2 Due to the low melting point of tin-zinc alloy (197 C), parts requiring de-embrittlement shall be heated to a p
15、art temperature of 187 +/- 5 C and held at this temperature for a minimum of four hours. 3.8 PROCESS REQUIREMENTS In order to successfully and repeatedly process this Tin-Zinc plating the following features must be incorporated into the process line. 3.8.1 Filtered rectification, less than 5 % rippl
16、e over the full range of rectifier output. Rectifier to have Automatic Voltage Control (AVC)/Automatic Current Control (ACC). 3.8.2 Dedicated heating and cooling equipment to hold process temperature to recommended level of 18 +/- 4 C. 3.8.3 Continuous instrument monitoring of temperature and pH for
17、 all process stages, with recorders. 3.8.4 Continuous plating bath recirculation. 3.8.5 Continuous plating bath filtration with 2 to 3 turnovers per hour. 3.8.6 Testing devices for plating thickness and alloy such as X-ray or Atomic Absorption. 3.8.7 Analytical equipment for titration and hull cell
18、testing. 3.8.8 Certification of tin/zinc anodes is required for less than 1/2 of 1 percent of metal impurities. 3.8.9 Conventional Neutral Bath, pH of 6 to 7. 3.9 THREAD ACCEPTANCE REQUIREMENTS (WA900, WE900, WX100) For thread acceptance requirements see Ford Worldwide Fastener Standards WA900, WE90
19、0, and WX100. ENGINEERING MATERIAL SPECIFICATION WSS-M1P95-A1/A2/A3/A4 Copyright 2015, Ford Global Technologies, LLC Page 4 of 4 3.10 CLEANING Prior to plating, the substrate shall be free of oil, dirt, and similar foreign materials. If a cleaning process is necessary, it shall have no detrimental e
20、ffect on the substrate, including freedom from embrittlement. 4. GENERAL INFORMATION The information given below is provided for clarification and assistance in meeting the requirements of these specifications. 4.1 SIGNIFICANT SURFACES Unless otherwise specified on the Engineering Drawing, significa
21、nt surfaces are defined as those surfaces of the finished part that: Are directly visible and/or visible by reflection when the finished part is assembled in position. Can be the source of corrosion products directly visible or visible by reflection. 4.2 TIN ZINC HEXAVALENT CHROMIUM FREE COATING AND BLACK FINISH Special finishes may be required on some parts, in which case the Engineering Drawing will be marked accordingly, for example: Tin/Zinc plate plus hexavalent chromium free passivate plus black finish.
