One of the worst enemies of aluminum is the oxidation that occurs from exposure to the natural environment, causing corrosion that usually harms the part or component. Ironically, the process that best guards against corrosion uses oxidation as its primary agent of change. Anodizing puts oxidation to use to create a hard coating. The process converts aluminum on the part's surface to aluminum oxide, a wear-resistant, corrosion-proof byproduct that protects the metal.

Anodizing is an electrochemical process that decreases the thickness of the metal while increasing the oxide coating. Standard anodizing utilizes sulfuric acid in conjunction with DC electrical current to form a hard oxide layer, one said to have hardness second only to a diamond. And, compared to other finish coatings, anodizing lends itself very well to coloring or absorptive dying because of the porous nature of the finish.

One of the largest contract anodizers in the country has multiple capabilities that few job shops can duplicate. Light Metals Coloring Co. (LMC), of Southington, Connecticut, can coat one large piece or thousands of small parts. And as its name suggests, the company offers a multitude of bright, lively designer colors, from cool greens and blues, to hot reds and oranges.

It doesn't matter if the part is a large, 16-ft extrusion or a tiny lid for a perfume bottle. While most large anodizers specialize in one area of the tradelike high-volume, rack cosmetic tubes or capsLMC handles a multiplicity of work with its large labor force of 130 employees. Accordingly, its very diverse customer base ranges into almost every SIC code imaginable.

"Because we're a big company with a large equipment inventory, we can handle just about any type or size of production run," says Mark Thomas, vice president of sales and marketing at LMC. "We have a three-shift operation, so we have the capacity to do large quantities of parts, but we also have the ability to perform processes that a customer would have to go to several anodizers to find. And, if necessary, we have engineers on staff that can assist customers with design and manufacturing challenges or that will formulate proprietary finishes for a customer's specific needs."

A new trend is emerging for job shops. Nowadays, OEMs often want contract manufacturers and providers of contract manufacturing services to provide a whole, completed product, from beginning to end, without consideration as to how much is completed in-house.

"The OEMs want one-stop shopping these days. With lean manufacturing and downsizing at OEMs, there is a trend toward outsourcing a complete product, even if they will have to pay contractors more money," Thomas explains. "They don't care how much of the work is sub-contracted out as long as they get a quality finished product at a competitive price. Even though we're primarily an anodizer, we do outside purchasing for machining, fabrication, metal stamping, and other processes on a regular basis."

The mainstay of the firm's business, however, has always been the anodizing. Light Metals Coloring provides bulk, rack, and hard anodizing in one shop. In bulk anodizing, the current flows from part to part since they are compressed and packed together in a titanium canister. Nonetheless, where parts touch there will be minor blemishes. Usually small parts, like rivets and fasteners, are run in bulk, since total appearance is not an important consideration. A large, flat, metal stamped plate could not be bulk anodized. Low price and the ability to do large quantities are the main advantages to bulk processing.

In rack anodizing, usually precision, machined parts are fixtured securely to titanium or aluminum racks, with the current flowing right to the parts. In this way, no parts come into contact with each other to cause surface marking.

One of two types of anodizing are employed in most applications. Type II anodizing is used for a variety of aluminum alloys, but typically has a thinner coating thickness ranging from 0.0003 inch to 0.0005 inch. Type II is available for applications that only need mild abrasion and corrosion protection. Type III, hard anodizing, adds superior qualities that include increased wear, corrosion, and electrical resistance. The thicker coatings range from 0.001 inch to 0.002 inch.

On the face of it, being all things to all people would not appear to be a good business practice, when most of the world has become more specialized. But it seems to work well for Light Metals Coloring.

"We're able to cater to a multitude of different types of businesses by setting up targeted business units within the company," said Thomas. "Each one is almost like a separate company within our larger company, and each unit specializes in a certain type of part or component, or finish. For example, we have one unit that does small-quantity parts that take tedious masking, and another that handles high-volume, rack parts. We have a specific unit for bulk anodized components, a 16-ft crane line that deals with large parts, and three hardcoat lines for Type III coatings."

Light Metals Coloring's long history in the business gives the firm an added sophistication. The privately owned company was founded in 1945, giving it the distinction of being one of the first anodizers in the US. In 1971, the firm moved into a new facility that it still occupies. Present owners of the firm are Mark Thomas and Richard Fleet, president, who took ownership in 1991. In 56 years of operation, they are only the third group of owners. Thomas says that it was an easy transition, since both of them worked for the previous owner for many years.

The firm has a very broad, diverse marketplace, with work completed daily in many different product areas. Its primary markets are automotive, military, medical, aerospace, electronics, cosmetics, semiconductors, and the food industry. Walking through the shop, visitors are likely to see anodizing and finishing processes in progress for medical instruments, automobile brake parts, M16 rifle parts, or components for helicopters, tanks, and missilesas well as for cooking grills, heat sinks, lipstick tubes, and picture frames. For the most part, LMC's sulfuric acid-based production equipment is similar to any found in the industry. However, the company operates modern, automatic rinsing tanks for its bulk lines, which expedite washing times greatly.

Furthermore, the company has an in-house rack fabrication department, allowing it to design and build tooling for its own fixtures and some racking. Automatic equipment on its process lines also facilitates the racking and unracking of parts more quickly. Moreover, custom work gives LMC the competitive edge that it needs for customers with special needs. The custom work is usually smaller, machined parts in small quantities with a lot of detailed masking requirements and close tolerances.

"It's not widget type of manufacturing," Thomas explains. "It's very tedious and time consuming work. For example, the semiconductor industry gives us parts that only need anodizing in specific areas of the part. Many anodizers don't want to do this work, but we find it a challenge."

Another area that LMC excels in is its use of proprietary processes, such as high-strength, dielectric coatings for the semiconductor industry. Other proprietary processes are used for hypodermic needle hubs and fine aluminum wire for the military. Since anodizing is an insulator, dielectric coatings provide an even thicker coating for increased insulation properties for higher current flow. Light Metals Coloring routinely holds tolerances from 0.0001 inch to the specific voltage breakdown minimum, which is another way to gauge dielectric strength levels.

Thomas said that these distinctive proprietary coatings are another reason that the firm's services are value-added. "Our engineers have devised most of these special coatings themselves," he revealed. "And we provide strict secrecy for our customers' coatings to keep competitors from using these substances. The whole world is trying to find out what these coating levels are, so we want to keep them a secret," Thomas admits. "We have one coating that only we and another U.S. company have, so companies all over the world are trying to find out what it is."

Another service that OEMs demand these days are secondary operations, whether they consist of implementing surface finishes, like polishing and sandblasting, or performing specialized coatings after anodizing to obtain extra wear resistance, a high-lustre appearance, or hardness. The company offers a large variety of pre- and post-anodic processes, with some executed in the shop and others vended out. These include dry film lubricating, deburring, Teflon coating, powder coating, plating, alkaline cleaning, sealing, and passivation, a surface conversion process for stainless steel.

"We can add additional coatings, like ceramics and lubricants, after anodizing to make the aluminum more chemical or wear resistant," Thomas pointed out. "We don't shy away from work that takes multiple finishes to complete, even if it has to be sent out. We have to have a lot of vendors to offer all of these coatings, but we want to supply our customers with a total solution. And, even though we only do aluminum anodizing in-house, we can do any metal a company may want by vending out the work."

Many anodizers provide parts with black coloring, but multiple colors (16 in all) and graphic effects are a specialty at LMC. One such process is a patented printing process called Aluprint, which combines anodizing with a specially formulated printing dye to achieve screen printing-like effects on aluminum. But, unlike silk screen printing, the Aluprint dye impregnates the metal for multi-colored applications like logos and nameplates. And the technique produces images that won't corrode, chip, or fade away.

LMC takes pride in its ability to problem-solve for customers. In one instance, a large manufacturer of computer components was powder coating a PC control knob. The company was having problems crimping the part after coating because the brittle paint coating would crack and shatter. Next, the firm went to several anodizers, but the anodized coatings were also too hard and cracked off.

"Eventually, they found us," said Thomas. "We devised a soft coating for them to give the part different crimping properties so it wouldn't craze during impact," Thomas commented. "Our parts looked good, we saved them about 20% on the part's original cost, and we decreased the number of rejected parts greatly," he added proudly.

Another solution was activated for a large bicycle builder who needed an anodized suspension system. The firm wanted the suspension to have a hard-anodized coating and an attractive, bright metallic look. It looked around everywhere but couldn't find one anodizer who could handle both requirements, until it found Light Metals Coloring. The anodizer devised a hard coating known as Nu-Coat, which is hard and durable, yet still very attractive. And, LMC was able to help the firm get the new bicycle to market a few months sooner than it expected.

These examples prove one of the company's credos: "We are proud of our ability to adapt and turn every challenge into an opportunity to excel."

Aluprint is a trademark of the Clariant Corp.