Metal Finishing Guide Book

2012-2013

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Figure 1. C-5 Galaxy, Aircraft dens and foster enhanced worker safety at OOALC. Under this effort, numerous interviews with OO-ALC personnel were conducted. The purpose of the interviews was to identify the technical requirements for the parts being processed and to capture the desired characteristics of an alternative sealer. CTC then identified relevant products by conducting Internet searches, vendor interviews, and literature reviews. This article presents the findings from the Figure 2. Main Landing Gear interviews with ALC personnel (requirements analysis) and product search (technology assessment) conducted during this effort. Although this activity focused on the specific needs of OO-ALC (e.g., military components and applications), the information and methodology presented herein is useful for anyone interested in exploring alternatives to dichromate sealers for anodizing operations. ANODIZING AND SEALING REQUIREMENTS OO-ALC uses sulfuric acid (Type II and Type IIB) and hard coat (Type III) anodizing at its facility. Therefore, processing and coating requirements for Types II, IIB, and III anodizing at OO-ALC were determined. Based on interviews with OO-ALC personnel, anodizing processes at OO-ALC are used to treat components made from 2000, 6000, and 7000 series Al alloys. The performance requirements for the three types of anodizing conducted at OO-ALC must meet the requirements of MIL-A-8625F, which are summarized in Table 1 [Ref. 6]. The acceptance criteria recognize that corrosion resistance is determined using the standard salt spray test in accordance with ASTM B117 [Ref. 7], and that paint adhesion is determined in accordance with Federal Test Method Standard 141, Method 6301 [Ref. 8]. (1See Table 2: Acceptance Criteria for Corrosion Resistance.) . SULFURIC ACID (TYPE II AND TYPE IIB) ANODIZING OO-ALC uses sulfuric acid (Type II and Type IIB) anodizing to anodize the components of various aircraft landing gear. Current is applied when parts enter into the solution and is gradually increased to the desired current density 375

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