Beyond the obvious—selecting floor coating, secondary containment trays, or berming, power, air, and exhaust requirements—the equipment selection process might proceed as follows:
- The equipment estimator must first collect all the data.
- Then, a determination of how many parts are to be finished per year, month, week, day, must be broken down into hours per day, in order to size the process line.
- Pretreatment requirements, such as burnishing, tumbling, deburring, buffing, polishing, or degreasing, and selection of any specialized equipment, must be considered.
- Selection of the process, which will depend on whether the parts need to be barreled or racked, is yet another factor.
- Determine a plating or anodizing process cycle for the particular base material, as well as the
- configuration of the parts.
- Determine if the plating thickness requires electroplating, immer- sion, or autocatalytic (electroless) processing or Type I, II, or III anodizing, etc.
- Carefully calculate the surface area of a single part to determine how many parts may be loaded per barrel, rack, or fixture.
- If the parts are to be barrel plated, then determine if the parts will nest, or stick together; and, if so, what type of barrels will be used. If the parts are to be racked, then each part needs to have a special rack or fixture designed to accom- modate that special part. If more than one rack per flight bar is required, determine just how many racks per load will achieve the best results.
- Masking considerations: Many parts will require masking with special tapes or waxes, as well as holes plugged with custom plugs.
- Reels of connector parts might require selective plating only in some areas, especially where pre- cious metals are plated. Customized selective strip plating lines will be required for each special application.
Once the production quantities are determined, then the plating facility must be sized accordingly. The plating tanks must be laid out, and the footprint of all lines and systems measured, with optional floor coating, double containment of the tanks, with catwalk and grating provided. If a manual line is sufficient for the desired production volume, with one or more operators, then it must be determined if an overhead hoist will be needed—and if so, will it be a manual chain hoist, powered trolley with push button, or joy stick variable-speed motorized hoist.
If an automatic hoist line is needed, then you’ll need to determine precisely how many hoists will be required. Depending on the configuration of the line, there might be parallel lines, side by side, with load, unload at the same end, or load on one end, unload on the other end, and with either wet or dry shuttle transporting the barrels or racks from one side of the line to the other, or a U-shaped return line, and dryer.
The PC software must be programmable in order to allow control of all the process parameters, such as solution operating temperatures; low-level shut off, alarms, auto-fill of tanks; variable or constant current and voltage requirement of the rectifiers; cathodic or anodic; automatic ramp up of voltage for anodizing; historical process data recorded for future records; hoist location, position, and speeds; pumps and filtration operation; air blower pressure; and amp min/hr. Other parameters to consider are chemical dosing, and if any brightener feeders or chemical feeders are supplied with metering pumps, etc.
In order to design the plating line(s) correctly, key items must considered for every single tank in the line. The designer must go through each station or tank, one at a time, to decide which controls or accessories need to be installed on each tank. A manual line would need the same items as an automated line, except the automated line would have either single or multiple programmable hoists, which might be either a monorail type, sidearm, semi-bridge, bridge, or a “rail rider.” The hoist positioning might be laser-controlled encoder or manual, with random loading scheduling—or it could be time-way based. The line might be totally enclosed because of either clean room or other environmental circumstances, with the operator working inside the enclosure.
All of the tanks must be sized to accommodate the barrels, or racks, with sufficient clearance for the heaters, sensors, coils, pumps, filters, spargers, level controls, anode baskets, etc. The tank material must be chemically compatible—with the decision to either line the tank, or offer it without linings or inner coatings—for each solution, as well as each individual component. Each tank must be outfitted with a variety of components, based on just what the tank is supposed to accomplish.
The soak cleaner would need either electric heaters or heating coils, temperature controllers, sensors, hi/lo level sensors, individual solenoids for city water or deionized water feed, agitation sparger (with agitation either provided by low-pressure, oil-free filtered air), or eductor/pump agitation. Other necessities: oil skimmer, oil coalescer, pump and filter, and low-level shut off of the heater.
The rinse tanks might require auto-fill city or deionized water solenoids, air sparger manifolds, drain valves, overflow weirs, conductivity controllers, and possibly pump and filter, depending on particulate drug into them. Electro-cleaner tanks would also need a rectifier, anode/cathode bars, pump and filter, oil skimmer, heater or steam coil, solenoids for city and deionized water feed, etc.
The process tanks would require similar components as the electro-cleaner, with an addition of rectifiers and other items, depending on the process. The rectifiers might be chosen to accommodate a variety of controls, such as constant current and/or constant voltage (pulsed, periodic reversed, or reverse pulsed; air, water, or convection cooled), and might include analog or digital amp/volt meters mounted remotely. The designer must decide just what type of heaters, agitation, cooling, filtration, circulation, rectification, and materials of construction, as well as what needs to be exhausted and which tanks need exhaust plenums. CFM requirements also need to be calculated for the entire line in order to size the air scrubber.
If the plating tank happens to be an electroless nickel process, then the decision must be made as to how to heat the tank. For example, would it be more practical to use heaters, steam, or hot water coils? Or does it make more sense to make the tank a double-boiler tank heated with coils in the lining of the tank?
CONSIDERATIONS WHEN DESIGNING A TANK
There are many considerations when building the tanks, including size, quantity, and spacing of the girths around each tanks, as well as factoring in the weight capacity of each solution. All of this depends on specific gravity, operating temperature, and geographical location. On the West Coast, for example, you might require seismic calculations on the larger tanks.
The plating lines might be either individual tanks sitting on a frame or modules. Either way, the lines should be plumbed with valves, solenoids, city and deionized water feeds, with separate drains to cyanide, acid/alkaline, and chrome lines to the wastewater treatment system. Note: every plating facility will need some type of treatment system, unless it’s all hauled away and treated off site. The plating line should offer single-point connections after arriving for hook up of the utilities, air, water, or steam, and electricity. Most plating lines are wired “three-phase” wherever possible for energy efficiency savings.
Some plating lines are required to provide VFC (variable frequency controls) that vary the speed of the electric motors on the pumps, etc., depending on load requirements.
The wastewater treatment system must have many components to accommodate the plating line, and the plating line designer is usually asked to also quote the wastewater system supporting the plating or anodizing line. Aside from considerations regarding the wastewater treatment methodology of each plating line, the designer must determine just which type of system will be the most efficient system for that particular line while satisfying the local permitting laws.
The aforementioned factors should offer readers just a few examples of the magnitude of calculations, researching, sizing, etc., that might be required when estimating a new system. If the process line is designed properly to begin with, then the chemistry will have a much better opportunity of being successful.
Jim Sutherland is a sales manager for CJI Process Systems in Santa Fe Springs, Calif. Prior to his joining CJI, he had almost 50 years of plating and metal finishing experience, and was certified under the AESF grandfather clause in 1980 as a CEF. He also received certificates for all the plating courses taught by Larry Durney at New Haven College in the early 1960s. Over the course of his career, Sutherland has held various positions, including technician, plant supervisor, and plant manager. He has worked for such operations as Harper Leader, Robert’s Plating, Chappel Industries, EMF, Production Finishing, and Winchester Electronics. Sutherland’s sales career launched in 1971, a year before graduating from the University of New Haven. After a stint as sales & service engineer for Truebrite Chemical, he was then recruited by American Chemical & Refining Co. as New England manager, selling and servicing precious metal processes and refining services. Sutherland also held positions with SERFILCO, HBS Equipment, ACS Environmental, Metal Surfaces and Allied Signal-Honeywell. You may e-mail him or visit the CJI's website.