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Time and time again we hear from customers looking to transition their passivation process in-house. In most cases the biggest concern cited is not always the cost to have the process performed by an external vendor, but the time. Between packing, shipping, unpacking, processing, repacking, shipping the parts back and unpacking them again many customers are seeing delays from several days to several weeks as they wait for their parts.
Overhead Exhausting Used for Nitric Acid Passivation Systems
Concerns about cost of the system, learning the process, understanding the chemistry usage and disposal and so on are frequently expressed when companies look at bringing the passivation process in-house. But the reality is that the process of moving your passivation needs in-house is much simpler than most people expect, and remarkably affordable, too.
In the case of one aerospace and defense manufacturer we worked with recently, the waiting game became unbearable and they had to move the process in-house. The company needed a robust system that could be fully automated, handle up to 150 pounds per basket of parts, provide monitoring of their various tanks of solutions, AND provide a reasonable return on investment in a relatively short period of time.
Enter the MK36 Six-Stage Passivation Line.
Stage 1: Alkaline Turbo Wash with Agitation
Stage 2: Overflow Rinse with Agitation
Stage 3: Citric Passivation
Stage 4: Overflow Rinse with Agitation
Stage 5: Cascade Rinse with Agitation
Stage 6: Dryer with Dual Adjustable Hot Air Knives
Each stage features a work platform that is 34” x 19” x 16” and can handle up to 150 pounds at a time. The units feature 90-gallon tanks and the wash includes an oil removal system with “Surface Sweep”. The units feature platform oscillation during cycle to provide agitation in the wet tanks, and to allow all portions of the parts to pass through the air stream from the air knives in the dryer. Each of the wet process tanks is also equipped with a vent collar to connect the tank into the building’s HVAC system for ventilation.
Video Demonstration of Pump Agitation in Wash and Acid Tanks
Stage 5, the Cascade Rinse with Agitation features a constant feed from the customer’s fresh DI source. In turn, as the tank continually overflows, the stream is fed into Stage 4 freshening that rinse. Stage 4 in turn overflows into Stage 2 rinse which helps keep that rinse fresh but also serves as a continual neutralization of the alkaline water in Stage 2. Because Stage 2 sees the greatest amount of dragout from the alkaline detergent in Stage 1, the water will tend to become more alkaline over time. Similarly, Stage 4 see the greatest dragout from the citric acid in Stage 3 and becomes acidic over time. This multi-tank overflow across the three rinse tanks allows for a slow, continual freshening of the solution in all three rinse tanks, and allows the acidic build up from Stage 4 to work as a natural neutralizer to the alkaline build up in Stage 2.
A powered conveyor on the input side of the system allows for loading of up to three baskets in queue. As the system operates it continually moves the baskets from the in-feed conveyor, through each tank and onto a gravity-fed output conveyor that allows the baskets to accumulate until an operator can take them on to the next step in the manufacturing process.
The passivation process tanks are automated with the patented articulated walking beam automation that insures precise process time and minimizes operator exposure to the various chemicals.
Since installing the parts cleaning equipment just a few months ago, the customer has already been pleased that they are exceeding the workflow they had originally planned for the system and it is working flawlessly. They estimate the system pay-off (cost savings versus price of machine) will take less than three years, and the management team has asked the manufacturing group to start a feasibility study for adding a second system.
