Implementation of Innovative Hard Chromium Plating Tooling at Corpus Christi Army Depot – Phase I and II

DoD Participants:  U.S. Army – Corpus Christi Army Depot

The National Center for Manufacturing Sciences (NCMS) Commercial Technologies for Maintenance Activities (CTMA) program has established a long track record of success in developing manufacturing technology which can be rapidly translated into real productivity gains for both industry and Federal facilities. Occasionally, a CTMA project comes along for which the immediate value of the cost savings and increased throughput it generates is remarkable even for the CTMA program.

Almost from the day it was launched, the Hard Chrome Phase I project had begun to assist a key DoD metal finishing facility in meeting critical production requirements.

Corpus Christi Army Depot (CCAD) operates one of the most modern, largest and busiest Defense Department (DoD) metal finishing facilities. More than 15 different metal finishing processes are present at this facility. Hard chromium plating is one of the most heavily used of these processes; CCAD chromium plates approximately 50 different aircraft parts with a total production load of approximately 4,500 parts per year. The labor-intensive nature of hard chromium plating also makes it one of the most expensive processes to operate at CCAD; more than 25% of the metal finishing staff works on hard chromium plating.

During this CTMA[1] Hard Chrome Phase I project, “no-mask” anodes for hard chromium plating two aircraft parts (horizontal pin and cover support from the CH-47) were developed and implemented. These particular helicopter parts were selected because of their production frequency (make up 36% of hard chromium plating workload) and because they are difficult to plate (i.e. significant reject/rework rate). The no-mask concept is relatively new to chromium plating. It involves the design/fabrication of a rack and anode fixture, which are customized to particular parts. The main advantages of this approach are reduced labor for masking, faster plating times and more uniform chromium deposits.

Overall, the project involved several stages of prototype design, fabrication and testing. A final set of production tooling was then supplied and CCAD employee training was performed. By the end of the project, the new tooling developed during the course of the work had been fully incorporated into the facility’s hard chromium plating operations, and continues to be in routine use.

Hard chromium plating provides superior wear resistance for a wide variety of surface geometries. Although there has been considerable effort over the past several years to develop alternative processes that can match its performance and flexibility, hard chromium plating is not likely to be superseded in the foreseeable future for many critical applications. The results of this project will enable plating facilities to produce higher quality parts with substantially less time and effort than was possible with previous technology.

Key benefits derived from the project include:

·   Annual labor savings of $779,623

·   Reduction in shop turnaround time of 48.6 and 74.9% respectively for the horizontal pin (H-pin) and cover support

·   Increase in plating tank capacity of 24.1% (achieved as a result of reduced plating tank residence time for the H-pin and cover support).

Based on the success of prototype tooling tests, a second phase of work was recommended, approved and currently underway which focuses on some additional difficult to plate parts, including high nickel alloys and the development of generic tooling for critical parts that are less frequently plated.