ABSTRACT

Three cost studies are presented that supported decisions by commercial manufacturers to change to Vapor Corrosion Inhibitor (VCI) packaging from traditional methods: oil coatings, and desiccant in barrier packaging. These legacy methods are still common in military applications where these cost models may be useful references. The studies show cost reductions of 35% to over 50% for cases of long-term storage and ocean shipment of mechanical, electrical and electronic equipment. Two of the studies supported decisions to replace oil corrosion prevention coatings on inter-plant ocean shipments of "Completely Knocked Down" (CKD) ferrous vehicle engine components. These two cases represent the broad trend that drove rapid company conversions in methods for worldwide shipments from "wet" (oiled) to "dry" parts and subassemblies protected with VCI packaging. The third cost analysis supported a specification decision to ship container loads of electronic control cabinets and other electromechanicai modules for a turnkey factory. Packaging used VCI film combined with VCI vapor capsules rather than desiccants placed in three-layer barrier packaging (MIL-B-131H Type 1 Class 1). Other critical decision factors included improved corrosion protection, process yields, quality and reliability, logistics, environmental compliance, enhanced workplace health and safety.

INTRODUCTION

Corrosion protection of metal surfaces remains a pervasive and costly problem for long-term storage and shipment of military parts and equipment ~, particularly when parts must be clean, uncorroded, and ready to use directly out of the package or shipping container. Vapor corrosion inhibitor materials were created about two decades ago 2 in various forms of polyolefin plastics that release volatile molecules over long periods of time. This fundamental invention of formulations and processes for making VCI plastic materials provided the basis for the continuing innovation in this technology, including polyethylene films, bags, foams, vapor capsules, tubes, rods and molded containers for an expanding range of applications. Their effectiveness and cost advantages in protecting parts and systems from corrosion have resulted in replacement of oil coatings and desiccants in commercial applications that parallel military usage. Examples of these applications range from engine components and other vehicle parts, such as those shown in figures 1 to 3, to electrical and electronic components and equipment, shown in figures 4 to 6, that contain a variety of critical-to-function metal surfaces that directly affect reliability, readiness, process yields, and other measures of the cost of corrosion.

Oils and other coatings are no longer an optimum choice for cost and other factors. Desiccants are another legacy materials used in the belief that they may protect clean parts. Without well-sealed enclosures that maintain extremely low moisture transmission, they become ineffective after a few days or weeks.

The military sector lags the industrial sector in replacing legacy methods, such as oil coatings, desiccants and barrier packaging, with VCI materials. This paper offers three cases of cost analyses that were developed for decisions by companies that changed to VCI packaging for protecting ocean shipments of parts and systems. These cost analyses augmented other critical decision factors that are mentioned but not detailed in the company studies, including improved productivity, process yields, quality and reliability, as well as intangible factors like improved work environment and safety. The three cost models may be useful for similar cost reduction studies in the military sector to support decisions about corrosion pro

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