Prime Wheel Rolls into Fully Automated Plating

When Henry Chen considered expanding his business, he found an opportunity in the production of OEM parts for major U.S. and Japanese auto makers. As owner of Prime Wheel of Harbor City, California, Mr. Chen and his team had become known as leaders in the production of chromium-plated aluminum wheels for the automotive aftermarket. Marketing well-respected product lines such as Prime Wheel, Image and Golden Wheel, the company's production capacity was good, producing up to 4,000 aluminum castings daily.

All the chromium plating was sent to outside sources, sometimes to as many as seven job shops. Mr. Chen wanted to be in the driver's seat. Prime Wheel's stringent quality assurance department spotted rejects at the rate of 30 to 40 pct. Mr. Chen knew he had to make changes if Prime Wheel was going to shift into high gear.

To maintain Prime Wheel's leadership position in the aftermarket and meet the increasing demand for OEM chromium-plated aluminum wheels, the company would have to accelerate production capacity. Mr. Chen also wanted to institute an even higher level of quality management. He decided the best way to control all of this was to take plating in-house.

A major expansion was needed to house the new finishing system. Working with Consultant Tom Beckwith, Mr. Chen set out to design and construct a fully automated chromium plating line.

The new system, which took two months to design and 10 months to build, features state-of-the-art equipment, each with its own back-up system. According to plating operation designer and construction supervisor, Mr. Beckwith, "Every procedure in the system has a back-up, including the boiler. This system was designed to meet and surpass the regulations of the extremely stringent South Coast Air Quality Management District. They are using this operation as a benchmark site for future standards."

Prime Wheel's plating expansion included an additional 30,000 sq ft, bringing the total manufacturing area to 600,000 sq ft. Prime Wheel now employs more than 1,000 people. Future plans also call for the construction of a 110,000-sq-ft production plant, which will increase casting production to more than 200,000 wheels per month.

To accomplish the desired levels of production and quality in its plating operation, Prime Wheel's plating tooling provider, Custom Industrial Rack, built the plating fixtures. Cosmos Minerals Corporation fabricated proprietary designed auxiliary anode hookups. Due to the complex designs of some of Prime Wheel's wheels, extremely precise plating procedures are required. These intricate auxiliary anodes are used to chromium plate hard-to-reach recesses and contours of the wheel designs. Mr. Beckwith noted, "The special design of these auxiliary anodes is a critical element in the success of this plating operation." Cosmos was asked also to provide anode baskets, special heating coils and shell-and-tube heat exchangers.

On board as finishing consultant and acting plant manager during the activation of the new plating line, Tom Beckwith instituted a strong set of guidelines for Prime Wheel's quality control procedures. Multiple checks and testing throughout the process include: Plating adhesion tests, in which the finished product must endure a torturous 45 min bake at 410F; Reverse saw cutting; and Micro-cross-section to ascertain consistency of plating thicknesses and grain structure analysis.

Prime Wheel's high quality plating can also be attributed to two procedures special to the plating industry. First, each Prime Wheel part receives a special initial treatment jointly designed by Brent America and Prime Wheel. Following this process, each wheel receives a proprietary pre-plate procedure before entering the first plating bath.

Brent America, Inc. provided the proprietary chemistry and technical support on the new wheel plating line from the immersion soak tank and power washer through the pre-plate immersion tanks. In addition to supplying pretreatment chemicals, Brent America also provided the pretreatment system for the powder coating operation and wastewater treatment chemistry.

Plating chemistries are supplied by Taskem. Acclaim HPD, process is used for plating bright acid copper. Copper metal is maintained at approximately 41 g/liter. Too high of a copper level will influence the maximum current density as well as the covering and throwing power of the solution. Deposit thickness would increase in high-current-density areas and decrease in low-current-density areas. Also, high copper levels can cause coper sulfate crystals to form on the anodes and tank walls, causing poor anode corrosion and deposit roughness.

It is also important for Prime Wheel to maintain both the anode and cathode current density. Too high a cathode current density causes burning and granular deposits. Too low a cathode current density reduces plating speed and can cause the copper metal concentration to rise.

Too high an anode current density causes anode polarization and a decrease in copper metal concentration. Too low a current density causes deposit roughness because the anodes dissolve non-uniformly. A typical operating procedure is listed in Table I.

Criterion Maxima AP bright nickel produces a uniform deposit over a range of current densities. pH is checked daily and adjusted. Hull cells are used for plating bath analysis.

Nickel sulfate and nickel chloride supply the nickel ions in the solution. The nickel chloride also improves the bath's conductivity and anode corrosion.

Cathode current density in Prime Wheel's nickel bath is the total current to the tank divided by the total cathode surface area. This allows for a wider operating current density range without burning.

The anode current density is calculated the same way, except the current to the tank is divided by the total anode surface area. A typical cycle is outlined in Table II.

Prime Wheel's new plating system was designed to include 32 tanks in a 160-ft line, with a work capacity of 12 wheels every five min. With its expanded capacity, Prime Wheel will increase its production from 80,000 to 200,000 units per month.

The company's testing and quality assurance have also seen a significant change, with a rejection rate of under one pct. With the move from outside sources to inside plating, Prime Wheel has increased its production capacity tenfold.

According to Prime Wheel's executive vice president of sales and marketing, Webb Carter, "This production expansion will help insure Prime Wheel's market position. Prime Wheel will now be able to keep more substantial and diverse inventories readily available for its customers. Additionally, Prime Wheel now has the control and capability to convert to meet OEM requirements as requested by automotive manufacturers."

So, what about Henry Chen's vision of expansion? It appears that Mr. Chen's success plan is right on target. Prime Wheel is negotiating with two major auto manufacturers to supply their chromium-plated aluminum wheel business.

TABLE I-Zinc Plating Bath Composition and Operating Parameters

	RANGE	TYPICAL
Copper Metal	37.5-52.5 g/liter, (5.0-7.0 oz/gal	41.3 g/liter, (5.5 oz/gal)
Copper Sulfate, Pentahydrate	150-205 g/liter, (20.0-27.3 oz/gal)	161 g/liter, (21.6 oz/gal)
Sulfuric Acid (Reagent Grade)	5-8 pct vol, 88.3-141.3 g/liter (11.8-18.8 oz/gal)	6.25 pct vol, 110 g/liter (14.7 oz/gal)
Chloride Ion	40-80 ppm	60 ppm
Temperature	23-26C (73-79F)	25C (75F)
Cathode Current Density	2.7-4.3 a/sq dm (25-40 asf)	3.2 a/sq dm (30 asf)
Anode Material	Phosphorized Copper (0.03-0.04 pct wt. P)	Phosphorized Copper (0.03-0.04 pct wt. P)
Agitation	Mild air agitation from a low pressure blower	Mild air agitation from a low pressure blower
Filtration	Continuous, through in-tank, cartride filtration equipment capable of 1-2 turnovers per hour	Continuous, through in-tank, cartride filtration equipment capable of 1-2 turnovers per hour
Heating/Cooling Equipment	Teflon, titanium, tantalum, quartz, or Karbate heaters and/or cooling equipment	Teflon, titanium, tantalum, quartz, or Karbate heaters and/or cooling equipment

NOTE: Copper Sulfate, Pentahydrate is 25.5 pct copper metal.

TABLE II - Bright Nickel Plating Bath Composition & Operating Parameters

	RANGE	TYPICAL
Nickel Metal	53-80 gm/liter (7.1-10.7 oz/gal)	75 gm/liter (10 oz/gal)
Nickel Sulfate	113-375 gm/liter (15-50 oz/gal)	250 gm/liter (33 oz/gal)
Nickel Chloride	60-113 gm/liter (8-15 oz/gal)	75 gm/liter (10 oz/gal)
Boric Acid	45-56 gm/liter (6.0-7.5 oz/gal)	53 gm/liter (7.0 oz/gal)
pH Rack	3.8-4.0	4.0
Temperature	49-66C (120-150F)	60C (140F)
Cathode Current Density	2.2-10.8 a/sq dm (20-100 asf)	5 a/sq dm (40 asf)
Anode Current Density	less then 3.8 a/sq dm (less then 35asf)	Same
Voltage	3-9 v	5.5 v
Agitation	Cathode rod or	Air