AutomotiveAutomotive ChromeChrome …… It’sIt’s BackBack By Dr. Donald Snyder

“As goes, so goes the nation.” It is not certain if GM has ever been large enough to have this much influence. However, during the 1950s and into the ’60s, it certainly could be stated that: “As the goes, so goes the plating industry.” During this period, many captive and jobshop plating companies were busy plating every elaborate bumper, grill and trim style that the automotive designers conceived. The more glitter, the better. Chrome was “in.” At the height of chrome’s popularity, if a plating shop had automotive business, times were good. Also, the use of chrome in other industries—such as kitchen appliances and furniture—was high, because their use of chrome traditionally follows the automotive industry. During the late ’60s and ’70s, however, the reputation of chrome became tarnished. By the early 1980s, external bright decorative chrome on automobiles was essentially non- existent. “Foreign styling,” unacceptable rapid corrosion, overbearing use of chrome parts and aerodynamically designed vehicles each contributed to the disenchantment with chromium, at least to the automotive manu- facturer.1 Plating shops had to shift to other parts to survive—several were forced to close. Therefore, a non-OEM source of chrome automotive parts had to be found.

Many Still Requested Bright Exterior Finishes The desire for plated bright exterior parts did not completely die in North America. For those who continued to appreciate the quality appearance of chrome on their vehicles, an industry was nurtured, primarily in southern California, to produce after-market, bright- chrome-plated automotive parts. During the ’70s and ’80s, this developed into a thriving business, particularly in plating steel, wire and, most recently, aluminum wheels. Glitzy after-market, bright-chrome- plated bumpers, roll bars, emblems and bright trim were also produced. To many consumers, putting chrome on their vehicle was like hanging jewelry on their beloved “pride- and-joy.” To others, it appealed to their macho, sporty interest. To satisfy customer demand, some new vehicle dealers offered after- market, bright-chrome-plated parts— especially copper/nickel/chromium-plated aluminum wheels. It became common for upscale autos, sporty , light trucks and recreational vehicles to have chrome-plated after-market parts. The parts provided these

38 PLATING & SURFACE FINISHING vehicles with an unique look and an enhanced curb and drive-by-appeal. The use of chromium on over-the- road trucks never died. Up-scale trucks continued to have chrome as standard equipment, and many chrome options were available for lower-level vehicles.

Automotive Companies Respond to the Demand It is hard to know for certain, but some cynical people believe that the after-market bright trim and wheel business grew so large and profitable that the automotive companies— especially those in the U.S.—wanted to benefit directly. In 1997, it was LHS reported that optional, plated alumi-

Popularity Outside the U.S. Table 1 not meet the more severe service Has Remained High Micro-etching Surface requirements of OEM parts. A less controversial reason pro- In the Far East, exterior bright trim Plating sequence for aluminum wheels posed was that the automotive dealers was never completely removed from Step Action and manufacturers observed that the vehicles produced there. They Polish Make surface reflective desire—and maybe even the de- maintained an average of 1–1.5 ft2 of Clean Remove soils mand—for bright work was great bright chrome-plated parts. Today, a Etch Micro-roughen surface enough to redesign it back into the few years after the trend started in Desmut Remove residue vehicle. Chrome parts make it easy North America, Far East automotive companies (especially in Japan and num wheels brought up to $800 in Table 2 Korea) are doubling the amount of profit per vehicle. This could be more Making Surface Platable bright trim on their high-end vehicles. profit than a dealer received for Plating sequence for aluminum wheels the rest of the vehicle. Others thought Step Action Chrome Is Back that the automotive companies did not First zincate “Clean” surface For whatever reason, the 1990s have want the potential liability if these up- Remove zincate Remove debris seen a slow but consistent increase in scale vehicles failed as a result of the Second zincate Adherent surface the use of OEM bright exterior failure of an after-market part. There was a particular concern for after- and relatively inexpensive for U.S. Table 3 market chromium parts supplied by designers to differentiate their Producing “Ideal” Substrate authorized automotive dealers vehicles and to distinguish themselves representing their respective OEM from foreign designs. Plating sequence for aluminum wheels companies. In most cases, after- To the automotive buyer, chrome- Step Action market decorative chrome parts would plated parts offer a unique, luxurious, Nickel strike Conductivity prestigious, durable and expensive Acid copper Leveling quality appearance. A late 1997 survey conducted by ABPA2 found automotive parts. It first started with that “56 percent of automotive top-of-the-line vehicles and has consumers say chrome enhances a moved slowly into the lower-line vehicle’s appearance.” In the ’80s, vehicles. They are receiving more this percentage would have been plated aluminum wheels, grills, door much smaller. ABPA also reports that handles, window trim, side panels/ the increased use of bright trim should body molding, bumper strips and last at least to the year 2010. emblems. Although not to the same extent as In the late ’90s, this trend became in North America, European automo- large enough for platers to observe the tive stylists are also adding more increased demand. Today, many bright chrome trim to their designs. A plating companies are near capacity, style popular in Europe, as well as in and some are building new plating other parts of the world, is toning lines. Also, companies not originally down bright chrome parts by giving in the plating business have started to Figure 1. Copper and Nickel over Aluminum - them a slightly dark, brushed or satin plate automotive parts. This is 500X Cross-Section appearance. especially true for companies that

September 1998 39 Table 4 rate is actually smaller than the Durable, Corrosion-resistant System industry’s average for OEM plated steel wheels. This is certainly one Plating sequence for aluminum wheels outstanding testimony to the durabil- Step Action ity of plated aluminum wheels. Semi-bright nickel Leveling & corrosion resistance It was not easy to obtain this low High-potential nickel Sacrificial layer return rate. It was the result of a Bright nickel Appearance, leveling & corrosion resistance tremendous amount of hard work on Nickel strike Produce micro-porous chromium the part of the platers with the Chromium Appearance/anti-tarnish cooperation of their suppliers and the auto companies. Because of the rapid, manufacture the parts being plated. of the fastest and least expensive naturally occurring oxide formed on In 1997, the Surface Finishing ways to change the curb and drive-by aluminum, aluminum requires the Market Research Board (SFMRB)3 appearance of a vehicle. It also helps most involved preplate sequence of estimated that about 10,000 job and in the quest to remove vehicle weight. the commonly plated substrates. A captive shops were involved in plating After the initial rapid growth in OEM typical, highly simplified plating in the U.S. The SFMRB’s 1997–98 plated aluminum wheels, the market sequence for aluminum wheels is report, states that more than 50 has been growing at an average of reviewed in Tables 1 through 4. A percent of all U.S. plating companies about five percent each year. At this more detailed description of the (in 1997 for captive shops and 1996 time, nothing appears to be adversely preplate steps can be found in the plus 1997 for jobshops) listed the affecting growth for the future. Even literature.5 automotive industry within their top the after-market business is increasing. The starting point for processing three segments of parts plated. This cast aluminum wheels prior to plating includes OEM and after-market parts. Low Return Rate is outlined in Table 1. A thick, uneven Although not surveyed, the percent- Requires Hard Work aluminum oxide coating on the wheel age of automotive platers is probably Aluminum wheels are subjected to the is removed during these operations. higher for Canadian plating shops. most demanding service environment To obtain the desired surface appear- The percentage of companies plating of any decorative part on a vehicle. ance, the wheel is subjected to for the automotive industry should Safety is also a major concern. For machining, grinding and polishing. continue to rise as a result of this these reasons, there must be no This is followed by a series of increased use of bright automotive question about the wheels’ durability. cleaning steps to remove the debris parts. Although the total surface area The plating industry has learned a generated by these physical processes covered by decorative chrome tremendous amount about producing and any other shop/processing soils. automotive parts will not return to the decorative plated parts that can last 10 The etch step removes the remaining level of the ’50s and ’60s, there is a or more years in service.4 The aluminum oxide from the surface and significant increase over the ’80s— industry has also learned how to apply leaves a micro-roughened surface. worthwhile for platers to pursue. these electrodeposited coatings to The desmut step cleans the surface of aluminum—a very hard-to-plate residual aluminum and aluminum Chrome-plated Aluminum substrate. Over the last four or five alloying oxides and activates the Wheels Are the “In” Thing years, platers adapted this technology surface, even the exposed silicon Originating from the small and in order to consistently plate high- contained in the castings. The proper fashionable after-market business in pressure (squeeze) castings (> 50% of application of this series of processing southern California, the most glamor- OEM) and low-pressure (atmo- steps determines the degree of ous and probably greatest increase in spheric) cast wheels to OEM specifi- adhesion of the electrodeposits. They exterior bright plated parts is plated cations. Throughout these years, the are also very critical in determining aluminum wheels. A dramatic wheel’s service performance has the final appearance of the wheel. increase in the production of OEM proven to be extremely good. A uniform, thin aluminum-oxide plated aluminum wheels has occurred At a panel discussion addressing coating forms on the activated over the last four to five years. bright chrome on automobiles that aluminum surface after the desmut Production that, five years ago, could was held early this year at the Detroit operation. The process steps in Table be measured in a few thousand after- International Auto Show (NAIAS, 2 remove this film and replace it with market wheels per year, is now January 1998), Dave Kuntz of Kuntz a tenacious, less active zinc/zinc salt estimated to have a worldwide Electroplating Inc. reported that they film dispersed with alloying metals. capacity of more than four million per had essentially no plated aluminum The first alloy zincate “encapsulates” year. OEM wheels dominate this wheels returned for plating rejects. any material remaining on the capacity. An estimated 50 plating This was from a pool of 1.5 million aluminum surface and removes it shops worldwide plate aluminum plated aluminum wheels produced when it is stripped. The second wheels, primarily for the U.S. market. over a 4.5-yr time period. Kuntz zincate film has a more open structure More than half the total capacity is in Electroplating is now at the 900,000 and is more uniform and thinner than the top five shops. plated aluminum wheels per year the first zincate. This film protects the This rapid increase in the use of level (two million in service after five aluminum surface from oxidation plated aluminum wheels could be years), with essentially the same long enough to cover the platable considered a fad, but it does offer one outstanding performance. This return surface with a nickel strike.

40 PLATING & SURFACE FINISHING Table 3 lists the specially formu- non-prioritized list of potential No matter what the future brings lated nickel strike step that protects replacements contains: for plated aluminum wheels or for the aluminum surface and zincate film plated bright automotive parts in from the acid copper plating solution. The Old Standard general, the increase in their use is An “ideal” substrate is next obtained • Steel wheels—painted or plated— adding excitement to the automotive by depositing a thick layer of acid highest weight industry. And, as the automotive copper over the thin nickel strike. industry goes, so goes the plating Acid copper imparts leveling, thermal Newer Approaches industry. P&SF protection and adhesion. In addition • Organic-coated aluminum wheels to the normal metal-to-metal bonding, • Organic-coated, micro-polished References the cross section in the figure demon- aluminum wheels 1. D.L. Snyder, H.A. Davies, and strates how the combination of the • Plated plastic or stainless steel G.A. DiBari, SAE Technical Paper nickel strike and the acid copper centers Series 900766, “Durability and deposit can actually mechanically • Plated plastic or metal “glued-on” Quality Performance of Today’s enhance the adhesion by plating down covers Bright Electrodeposited Steel into a pit/void. The adhesion is so • Organic/metal composite coatings Bumpers,” International Congress good that, when the deposits are • Plated two- or three-piece wheels and Exposition, February 26– pulled from the wheel, the aluminum • Plated or organic-coated magne- March 2, 1990. substrate fractures and not the sium wheels 2. The Automotive Bright Products electrodeposits. Association (ABPA), phone: 248/ Even though acid copper electrode- All of these competing approaches, 641-3880. posits have very good leveling and others, are in use today. There is 3. SFMRB reports can be obtained properties, additional leveling of the still enough demand for plated from AESF: 407/281-6441. casting can be obtained by polishing/ aluminum wheels, however, that the 4. D.L. Snyder, “Fifteen Years of buffing the soft copper deposit. Low- total number plated is still increasing. Outdoor Corrosion of Trivalent and pressure (atmospheric) castings Hexavalent Chromium Electrode- typically contain enough porosity/ Changing Technology posits,” Metal Finishing, 87, 113 voids to require buffing of the acid Even though the plated OEM alumi- (June 1992). copper deposit for maximum appear- num wheel market is only about five 5. L. Harrison, N. Martyak, J. ance. The acid copper deposits on years old, the plating technology is McCaskie, M. McNeil, and H. high-pressure (squeeze) castings already mature. This is just another Smith, Plated Aluminum Wheel typically do not need polishing, example of the rapid changes taking Characterization, Metal Finishing, because the castings are relatively place within the traditional plating 89 (December 1994). free of pits/voids and perturbing industry. The technology also contains silicon. The polished/buffed copper some health/safety/environment About the Author deposit shown in the figure demon- issues. Some areas where changes are Dr. Donald L. strates its leveling ability. currently being made, in no particular Snyder is world- Table 4 lists a sequence of electro- order, are: wide technical plating steps that many aluminum marketing man- wheel platers utilize, depending upon • Nitric acid free Etch—Table 1 ager for Atotech the specifications followed. This • Reduced pore/void in castings— GMF, Rock Hill, combination of nickel layers that Table 1 SC. He currently electrochemically interact with each • Improved plating sequence for chairs AESF’s other offers maximum corrosion other aluminum alloys—Tables 1 Hard Chromium resistance for the thickness of nickel & 2 Plating Commit- used. If this sequence of deposits had • Non-cyanide Zincate—Table 2 tee. He also serves on the ASTM-ISO been developed in the ’50s and ’60s, • Nitric-acid-free Zincate re- Review Committee and the Scientific many of the corrosion failures during mover—Table 2 Achievement Awards Committee. that time might have been avoided. • High-throw Nickel Strike—Table 3 • High-throw Acid Copper—Table 3 Competition and Costs • Higher leveling Copper and As with most large, successful Nickel processes—Table 3 & 4 products, competition and cost of • Hexavalent Chromium free production become significant. Chromium—Table 4 Weight reduction for the vehicle, design flexibility, established produc- Costs, performance/durability, safety, tion capacity, engineering costs, and competition are a few driving durability and assembly factors all forces to continuously improve upon contribute to the cost and acceptabil- the technology. The foundation was ity of potential competing products. built over the last, very exciting, five The proven durability of a plated years. Perhaps the next five years will aluminum OEM wheel is now the be equally productive. standard to beat. A non-exclusive,

September 1998 41