Reducing Hazardous Waste and Turnaround Time with No-Mask Electroplating Methods
Advanced Tooling for Chrome and Nickel Plating; Modernization of Nickel Electroplating at Depots
Since its inception in the 19th century, the basic process of electroplating has remained fundamentally unchanged—objects to be plated are immersed in a bath of dissolved metal, and an anode is used to supply electric current, depositing metal on the object’s surface. Electroplating has numerous uses, ranging from providing heat- or corrosion-resistant protective coatings to reducing friction to laying under-coatings that improve the adhesion of other materials.[1] However, traditional methods are time-consuming, labor intensive, waste up to 90 percent of the power they consume,[2] and produce significant amounts of hazardous waste.
To demonstrate the feasibility of overcoming these challenges in a real-world maintenance setting, the National Center for Manufacturing Sciences (NCMS) and partner organizations introduced the use of an out-of-tank plating method using no-mask conforming anodes in Department of Defense (DoD) depots. In it, metal solution is circulated through water- and airtight fixtures shaped to accommodate specific parts, obviating the need for a bath or manually applied maskant. No-mask electroplating carries with it significant advantages, including cycle time and labor cost reductions, reduced volume of hazardous waste, and ability to accommodate parts that traditional methods cannot effectively plate.
Cycle time for components that, using traditional methods, would require masking decrease by 35 to 50 percent when they are plated with no-mask conforming anodes. The process shows immense potential not only for improving the efficiency of existing maintenance capabilities, but extending them. NCMS project partners were able to use it with the worn rotor blade tips of two helicopters, the CH-47 Chinook and the AH-64 Apache, parts for which no repair processes previously existed. The replacement of traditional electroplating with the no-mask process was not confined to a limited set of easy test cases, either; project teams demonstrated the merits of the technology with nickel and hard chromium, “selected based on their volume, long plating cycles, labor-intensive masking and machining, and relatively high reject or rework rates.”[3]
Benefits
In technical performance terms, no-mask electroplating has several obvious advantages. It minimizes the formation of “trees,”[4] irregular, branching nodules of metal that are a wasteful by-product of the plating process. Conforming anodes deposit metal more uniformly, reducing need for subsequent machining and significantly reducing cycle time. The use of fixtures that kept metal solution circulating around parts instead of tanks minimizes the risk of hydrogen embrittlement. Silicone inserts allow platers to work with parts containing intricate cavities. All of this leads to a more efficient plating process that can be performed more quickly with less labor, for a higher-quality end product.
The real-world cost savings of adopting no-mask electroplating are significant. Over the course of NCMS’ projects, no-mask electroplating yielding savings of $7.4 million for two DoD installations, the Corpus Christi Army Depot (CCAD) and the Navy’s Fleet Readiness Center Southwest (FRC Southwest). The process was subsequently adopted by other installations—seven depots saw annual savings of $5.9 million. DoD-wide adoption of no-mask electroplating would result in an estimated $50 million in savings over three years.
A significant source of inefficiency in traditional electroplating methods is the “hazardous, tedious, [and] error-prone” process of applying maskant.[5] According to Randy Taylor, president of Advanced Tooling Corporation, maskant is time-consuming to apply, and reliance on manual application introduces a source of operator error. The material—which can take the form of tape, wax, glue, or other coverings—can also be cumbersome to remove, and removal must be performed quickly so that the part can be placed in an oven to prevent embrittlement from hydrogen exposure that may occur during immersion. Inconsistencies in maskant application can result in an unacceptable amount of variation in final, plated parts.
Worst of all, maskant is single-use, becoming contaminated with metal solution when it is immersed in the plating bath; all used maskant must be handled as hazardous waste.[6] Discarded maskant forms only part of the wide array of waste products traditional electroplating generates, from contaminated filters and wipes to spent solutions and anodes to tank sludge and rinse water, all of which require treatment and/or specialized disposal.[7]
Summary
NCMS and its partners, through NCMS’ Commercial Technologies for Maintenance Activities (CTMA) program, conducted a quartet of projects introducing the use of new commercial electroplating processes within DoD depots. Electroplating forms an essential part of Department of Defense (DoD) asset maintenance—depots use it as an anti-corrosion treatment and a way of resizing worn parts for vehicles and weapons, including small arms, tanks, ships, and aircraft. As an alternative to these depots’ preexisting plating capabilities, NCMS used no-mask fixtures in place of tradition maskants. The initial three projects successfully applied the no-mask concept to hard chrome plating, while the last successfully extended the concept to nickel electroplating. All of them resulted in improved product quality and major cost savings.
No-mask electroplating was implemented in the refurbishment of aircraft parts by CCAD and FRC Southwest; the process had not previously been used by military depots, but upon introduction, it demonstrated immediate improvements over prior processes. Its use to repair CH-47 Chinook rotor blade tips which would otherwise have had to have been discarded and replaced produced $258,000 in annual savings. Similarly, CCAD was able to employ the no-mask approach to repair blade tip caps for the AH-64 Apache helicopter, parts that also did not have a preexisting approved repair process. FRC Southwest focused their efforts on Rotodome Gearbox Housings, which had an approved repair process that was expensive, time-consuming, and often resulted in rejected parts and rework.
By the time project work had concluded, CCAD and FRC Southwest employees had been trained in use of the new process, and a final set of production tooling was supplied to both installations.
Project Partners
- S. Army – Corpus Christi Army Depot (CCAD)
- S. Navy – Fleet Readiness Center (FRC) Southwest
- Advanced Tooling Corporation
- CAI Resources Inc.
[1] “Explore the Many Benefits That Electroplating Can Provide for Your Business,” Surface Treatment Experts, accessed November 29, 2017, http://www.sharrettsplating.com/benefits.
[2] “Electroplating Breakthrough With No-Mask Conforming Anodes,” Quality Digest, accessed November 27, 2017, http://www.qualitydigest.com/inside/twitter-ed/electroplating-breakthrough-no-mask-conforming-anodes.html.
[3] “Electroplating Breakthrough With No-Mask Conforming Anodes.”
[4] “Gray Matter: Nickel Growing in Trees,” Popular Science, accessed November 30, 2017, https://www.popsci.com/diy/article/2006-03/gray-matter-nickel-growing-trees.
[5] “DoD Touts ‘No Mask’ Plating Process : Paint BidTracker News,” accessed November 27, 2017, http://app.paintbidtracker.com/news/?fuseaction=view&id=7034.
[6] National Center for Manufacturing Sciences, No-Mask Tooling for Electroplating, 2011, https://youtu.be/cTTxyC9XhMM?t=27s.
[7] “A Guide to Electroplating Waste Management” (Pinellas County Solid Waste, https://www.pinellascounty.org/solidwaste/PDF/electroplating_waste.pdf).