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Overview of the plating shop. Meticulously clean, the shop is designed for precision plating of high-tech parts. The hoist goes through the cleaning cycles and then diverges to go through either cadmium or chromium plating. Anodizing is also providedt
Luis Alvarez, NDT Level II inspector, tests parts using magnetic particle inspection, a non-destructive test method that uses ultraviolet light to screen ferrous parts for defects.
Mario Teodocio, plant floor lead, transfers aerospace parts through the cadmium plating line. Parts are rotated on the bus bar during plating to ensure even distribution. Jesus Teodocio is the cadmium line operator.
Mike and Spence Nelson started Hi-Tech Metal Finishing in Lewisville, TX, more than ten years ago to serve as a primary supplier to Mayday Manufacturing, a company started by their father in the 1960s. Mayday is a leading aerospace machined-parts manufacturer. Originally, the brothers envisioned Hi-Tech as a captive aerospace parts plating shop. However, they soon realized that this new stand-alone business could serve the needs of many other regional aerospace parts manufacturers in addition to Mayday.
Jim Nelson, their father, started Mayday as a rapid-response company with expertise in manufacturing precision bushings, sleeves, pins and spacers and other close-tolerance machined parts used in the commercial and military aerospace industry. Today, Mayday’s Rapid Response Cell is capable of supporting parts needed on an emergency basis by delivering complete components in just days, as opposed to weeks or months. Hi-Tech Metal Finishing, which is co-located in the same industrial park with Mayday, is an essential element in Mayday’s ability to achieve its Rapid Response strategy.
As Spence Nelson noted, “In the early 90s, Mayday could accomplish all sorts of innovative machining improvements, but many impediments occurred with traditional plating subcontractors. We could complete the machining steps on many of our parts very quickly, yet, when we sent them out for processing, problems occurred. In one year, Mayday had a 4% rejection rate from subcontractors. “Our first reaction was to pack up all the parts and send them back for sorting and replating. But, after considering freight charges and the possibility of damage and loss, Mayday decided to return only the small percentage of parts that required rework.”
“It was chaos,” as Mr. Nelson stated. The company would have hundreds of parts out for processing. Since some pieces were returned to vendors for rework, the balance of those lots were stored all over Mayday waiting for the rework to be completed. “All of this extra activity and time contributed to extra cost and late deliveries ,” noted Mr. Nelson. “The inconsistencies from Mayday’s supply chain continued even after a lot of discussion with them. In some years the work was outstanding and much improved; in others it was unacceptable.”
In a strategic move aimed at the preservation of the company’s future, the brothers decided they needed to be in control of the finishing, which is done on virtually every part that Mayday manufactures. “It is rare that a part isn’t finished,” commented Mr. Nelson. The Nelsons went to their prime customers and explained the difficulty Mayday was having with its supply chain. The support of its customers helped the Nelsons with their final decision on starting an in-house plating operation, and thus Hi-Tech Metal Finishing was born.
Both men realized that you cannot just “start up” a plating shop. Several hurdles had to be overcome. Number one was that they did not know much about plating. They started by hiring an accomplished retired plating shop owner as a consultant. An employee in Mayday’s Quality Control Department studied at the Kushner Electroplating School and also spent time, at Hi-Tech’s expense, learning plating at area plating shops.
The second hurdle for the Nelsons was to obtain finishing approvals from primary customers such as Boeing, Bell Helicopter, General Dynamics, Grumman, McDonnell Douglas and Northrop.“Requesting approval is a laborious, long, tedious process, and then they (the customers) decide whether or not it is to their benefit to have you approved,” noted Mr. Nelson. “You can’t decide you want to plate aerospace parts and then go to the customers and say, ‘We are going to put in a plating line, will you approve us?' You have to install the facility, organize the specs, prove that you can meet the requirements and then ask for a representative from the company to come for an approval visit. We did have an advantage, since Mayday had a long history with many of these companies, including the approvals for manufacturing parts.”
Each customer requires its own approval; however, with the advent of NADCAP (National Aerospace and Defense Contractors Accreditation), customers can rely on this to certify subcontractors, thus saving time and money.
NADCAP helps both the customers and the subcontractors with the approval process. NADCAP represents major contractors, suppliers and government agencies in the aerospace and military defense and related industries throughout the United States and internationally. Audits are administered by the Performance Review Institute (PRI), an independent, non-profit association affiliated with the Society of Automotive Engineers.
Hi-Tech is nearing completion of its NADCAP approval project (see sidebar). However, in the beginning, it had to earn its approvals one at a time via visits from quality representatives from each of the major aerospace companies. Once Hi-Tech Metal Finishing’s name showed up on all the approval lists, it prompted a deluge of calls from other machine shops in the area with similar problems. “At first we declined the extra work,” explained Spence Nelson. “We did not have the capacity, nor did we feel that we were completely ready to plate parts for other subcontractors. We were okay using Mayday as our ‘experimental customer,’ but not other contractors.” Hi-Tech’s approvals were for cadmium plating, passivation, magnetic particle inspection and liquid penetrant inspection. “Magnetic particle inspection and liquid penetrant inspection are not actually finishing processes,” stated Mr. Nelson, “However, most aerospace plating operations perform these traditional non-destructive testing (NDT) services because the machining community wants these tests done along with other plating processes required. They also want all steps completed under the fewest number of purchase orders possible and with the shortest possible lead time.
Beginning in 1995, Hi-Tech gained confidence and resources and began offering plating services to companies other than Mayday. Because of substantial interest from outside companies, Hi-Tech added processes (it is certified for 75 processes and growing) and eventually upgraded its facility from its original Lewisville, TX, to a greatly expanded location in Denton, TX. Now, the company has the capacity to perform hard chromium plating, chromic and sulfuric anodizing, Alodine/chemfilm, heat treating and prime and paint, along with its original cadmium plating ability. Hi-Tech has also expanded the number of prime customers it works with and will have more opportunities when NADCAP approval is complete. Hi-Tech works to most of the major prime specifications and serves about 250 customers across the whole aerospace spectrum.
“NADCAP approval was a big hurdle,” noted Mr. Nelson. “We did it because almost all of our customers were heading in that direction, and we are only involved in aerospace specifications. Plating aerospace parts is a tightly controlled business, and we went after the approval because we are certain it will be absolutely mandatory in the near future to even be able to compete for aerospace work.”
“Each prime customer has a different set of instructions for how it wants its parts plated. Many are similar; however the chemistry, titrations and recipes, for instance, may be different. We take the primes’ specifications for each process and find the best average or middle ground that will satisfy all of its specifications,” explained Mr. Nelson. Many of the specifications are based on military standards and tweaked; however, most of them are fundamentally the same, according to Mr. Nelson (see Table I).
It is important, however, that Hi-Tech know the hardness of the incoming parts as well as what the substrate is so that the proper cleaning methods can be used.
Titrations are done three times a week on the finishing baths, and the results are charted and posted for all Hi-Tech personnel to examine. Most chemical additions are small, because such tight tolerances are maintained. To maintain strict temperature requirements, some tanks have steam coils on one side and refrigerated coils on the other side. The chromium plating tank, for example, must be maintained between 128 and 133F.
Amperage is also important for each lot of parts. The Boeing cadmium specification, BAC 5701, states that a plater must use 10-60 asf. To determine the correct amperage, Hi-Tech calculates the sq ft for each part, which is usually a fraction of sq ft. Then, the sq ft is multiplied by the number of pieces racked. This determines the amperage necessary to thoroughly plate each load of parts. All plating variables are recorded and the data is maintained so that even ten years from now Hi-Tech can go back and determine just how a particular part was plated. “We finish some parts that are very high value, provided they are plated to the right tolerance. If we are off by even a mil, the part could be scrap and worth pennies per pound in scrap metal value,” noted Mr. Nelson.
Often customer requirements include testing. Hi-Tech has the capability to perform non-destructive tests such as magnetic particle inspection and liquid penetrant inspection.
Liquid penetrant inspection (LPI) is relatively easy to use and flexible. It can be used to inspect almost any material as long as the surface is not extremely rough or porous. The fluorescent material can be applied by dipping, spraying or swabbing. Hi-Tech uses it to inspect critical aircraft components for flaws. To inspect larger areas, the parts can be dipped. LPI is highly sensitive to small surface discontinuities; can be done rapidly and at low cost; can be used on parts with complex geometry; and indications are produced directly on the part's surface, giving a visual indication of the flaw.
Magnetic particle inspection also tests for defects. Unlike LPI, the part must be made from ferromagnetic materials. The testing uses magnetic fields and small magnetic particles, such as iron filings to detect flaws in components. The magnetic particles are suspended in a solution of highly refined kerosene. There are two types of magnetic particles, those that can be seen in normal white light and those that can be seen using fluorescent light. Hi-Tech uses fluorescent lighting, which uses a black light that causes the particles to glow, indicating flaws.
The symbiotic relationship of Mayday Manufacturing and Hi-Tech Metal Finishing has allowed the Nelsons to provide the aerospace industry with a source of top-quality parts. In some cases, Mayday already has a part required because of its Overrun Inventory, which is a sophisticated, cataloged parts storage system that has some of the parts the company has manufactured previously. Mayday also maintains a huge repository of blueprints to use in manufacturing and finishing parts. The company also provides to its customers a web site with up-to-the-minute information on its current inventory. This allows the company to produce finished parts more quickly, which is a major advantage in the aerospace manufacturing industry.
The Nelson’s visions go beyond Mayday Manufacturing and Hi-Tech Metal Finishing. The brothers are developing a 25-acre parcel of land around their co-located machining and plating facility. They are calling this new development the Allied Industrial Park. Its purpose is to serve other aerospace manufacturing organizations. They think there is some opportunity for shared services in administration and quality assurance that could benefit all companies on the compound. However, the major benefit would be that others could also benefit from a co-location strategy with a vitally important finishing subcontractor without having to invest the millions of dollars and the risk of managing such an enterprise. “If any machining operation could depend on a few days of processing time rather than weeks, a 25% reduction in your current expenditures for plating and metal finishing services, elimination of all your packaging and transportation cost and time and compress their overall lead-time to customers by 50% or more, don’t you think they would be interested?” asked Mr. Nelson.
In addition to these advantages, local and regional governing bodies have provided businesses looking to co-locate in the Allied Industrial Park several incentives, including the following: free port exemption, tax abatements, utility demand charge reductions and industrial revenue bonds.
|About Hi-Tech Metal Finishing|
|For more information, contact:
Hi-Tech Metal Finishing
Phone (940) 243-0516
Fax: (940) 243-2938
“We are poised for growth,” stated Mr. Nelson. “This is Hi-Tech’s first year with more than 50% of our revenue coming from outside customers. We have gone from a captive shop to one that is primarily focused on outside customers. Our goal is to grow Hi-Tech Metal Finishing into national aerospace prominence, and we think our ratio will be 80% outside customers and 20% of our capacity used by Mayday within the next five years,” Mr. Nelson predicted.
TABLE I. Cadmium Processing for Stainless Steel Parts
1. Inspect dimensions. O.D., I.D. and any other aspects.
2. Rack. Parts that are clean and do not require masking may be racked for plating prior to precleaning.
3. Clean. Record time and temperature.
A. Aqueous clean in tank 10 for 15 seconds - 30 minutes, until parts are clean.
B. DI rinse in tanks 20 and 30 for 10 seconds minimum and 3 submergings.
C. Alkaline clean in tank 40 for 30 seconds - 10 minutes.
D. DI rinse in tanks 50 and 60 for 10 seconds minimum each and 3 submergings. 4. Dry using compressed filtered air if baking, blasting, masking and/or racking is required.
5. Preplate Bake if required. Place clean parts in oven baskets and place in oven for time and temperature required for the parts. Record time and date in and time and date out.
6. Clean if baked. Repeat step 3. Record time.
7. Grit Blast/Glass Beads if needed. Record type used, distance and pressure.
A. Abrasive clean parts according to HITOP-009-07. Be careful not to damage or warp parts.
B. Blow off excess grit blast or bead using dry, filtered, compressed air. (Low-alloy parts must be plated within 4 hours of mechanical cleaning.)
8. Mask, if required.
A. Mask parts according to shop traveler or blueprints.
B. A part check must be approved and signed off on before completing the masking on the entire job.
(Masking materials include lead tape, plugs, wax and others)
9. Rack/Barrel. Ensure proper electrical connection. If barrel plated, parts may be cleaned in the barrel or in another container before being placed in the barrel.
10. Clean. Repeat step 3.
11. Acid Clean. Record time and temperature.
A. Immerse parts in tank 70 for 10 seconds - 2 minutes maximum.
B. DI rinse in tanks 80 and 90 for 10 seconds minimum and 3 submergings.
12. Descale, if needed. Record time and temperature.
A. Descale in tank 430 for 10-20 minutes.
B. DI rinse in tanks 440 and 450 for 10 seconds minimum each with 3 submergings.
C. If parts have smut after descaling, repeat acid cleaning step 11.
13. Nickel Strike. Record time, temperature and voltage.
A. Immerse parts in tank 100 for 2-5 minutes for rack jobs and 5-15 minutes for barrel jobs. Record time, temperature and volts.
B. DI rinse in tanks 110 and 120 for 10 seconds minimum each and 3 submergings.
14. Cadmium Plate. Class 1, 0.0005 minimum thickness approximately 10 minutes. Class 2, 0.0003 minimum thickness, approximately 8 minutes. Class 3, 0.0002 minimum thickness, approximately 6 minutes. Record time and amperage.
A. Immerse parts in cadmium solution.
B. Adjust voltage to provide current densities that will produce cadmium plating that meets the requirements for this job.
C. Use auxiliary anodes if needed to ensure required thickness of cadmium plate.
D. Rotate parts to prevent unplated areas.
15. DI Rinse. Use tanks 150,160, 170 and 180 for 10 seconds minimum each, inspect and record the dimensions. If no further processing is required, go to iridite step.
16. Dry using compressed filter air if baking magnetic particle inspection and/or unmasking is required.
17. Unmask and inspect for proper plate coverage.
18. Clean if masked. Repeat step 3. Dry with compressed filtered air.
19. Relieve Hydrogen Embrittlement if required.
A. Parts must be baked within 1 hour of plating.
B. Place parts in oven baskets and then into oven for time and temperature required. Record time and date in and temperature and time and date out.
20. Clean if baked. Repeat step 3.
21. Magnetic Particle Inspection, if required.
22. Reclean, if needed. Record time and temperature.
A. Immerse parts in tank 130 or 140 for 5-10 seconds with no current.
B. DI rinse in tanks 150-180 for 10 seconds each and 3 submergings.
23. Neutralize. Record time and temperature.
A. Immerse parts in tank 200 for 5-15 seconds.
B. DI rinse in tank 230 for 10 seconds minimum and 3 submergings.
24. Iridite (chromate). Type 1 does not require Iridite.
A. Type 2 (yellow). Immerse parts in tank 240 for 3-20 seconds. Record time and temperature.
B. Type 2, clear. Immerse parts in tank 270 for 10-30 seconds. Record time and temperature.
C. DI rinse in either tank 250-260 or 280-290 for 10 seconds minimum and 3 submergings.
25. Dry with compressed filtered air.
26. Unrack wearing latex gloves.
27. Inspect parts. Parts should be smooth, continuous, adherent and free from blisters, pits, nodules, porosity and indications of burning.
28. Test for adhesion.
Waste treatment is carefully monitored by Jeremy Adams to ensure that cyanide goes through complete destruct and no heavy metals are sent to the POTW.
Luis Alvarez, NDT Level II inspector, tests parts using magnetic particle inspection, a non-destructive test method that uses ultraviolet light to screen ferrous parts for defects.
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