ZN-Process

Typically, the drawback with zinc has been that it is too soft for some applications. But the IOSSO-ZN zinc plating electrochemical process, controlled to provide critical mechanical tolerances with uniform coverage, is said to bring the surface hardness of zinc up to 68 to 72 Rockwell hardness. The coating process bonds directly with the metal's exterior, creating a "new skin" with improved hardness and non-magnetic and static-free qualities that suit it for abrasion-resistant applications.

As a result, parts that had previously been made from steel can now be produced from zinc. The hardened surface is said to be uniform over complex shapes with no buildup. Parts last longer, the company says, because bonding with the base zinc alloy eliminates peeling, flaking, or spalling of the hardened surface.

"It allows people to have a lower-cost material and a lower-cost way of die casting, which is a very interesting way to make a part rather than machine it. Die Casting is fast, and now (with the process) you have a hard-coat surface and corrosion resistance," said Richard Iosso, president of Iosso Metal Processes, an ISO 2011 certified company in Elk Grove Village, Illinois. "So what we do is we develop a part with a customer and do a trial; they furnish us with a part and we go ahead and apply our treatment to it. They run an evaluation test on it and away we go. There's a lot of cost savings."

The Iosso-ZN process is a patented proprietary process that hardens zinc component wear parts. The coating bonds directly to the zinc alloy surface, resulting in a new surface that is reported to be extremely hard and wear-resistant. Design engineers can now look to zinc die castings to replace more expensive alloys, said Iosso Operations Manager Don Ortmann, adding that zinc has become an economical and feasible material to manufacture parts, especially those with critical mechanical tolerances.

While working as a sales manager for a cutting-tool company, Iosso investigated making the edges of tools stay sharp longer. With a background as a chemist, he began developing and testing different compounds, eventually arriving at a chromium-based alloy coating that improves wear-resistance. The thin, dense coating worked on cutting tools and component parts. In 1970, Iosso decided to take his process to market and founded Iosso Metal Processes (www.Iosso.net).

Before the process was developed, zinc was treated with an over-plating of copper, nickel, and chrome, for mostly decorative purposes. But the zinc plating process developed by Iosso extends the wear and corrosion resistance of the part while adding to the lubricity, allowing customers to utilize a longer-lasting part. The zinc alloy surface, with its hard outer case, allows designers to incorporate die cast technology with the IOSSO-ZN process to produce economical components with strength and precise, close tolerances.

IOSSO maintains that the zinc plating process makes zinc die casting the fastest, most convenient one-step manufacturing process to produce complicated metal parts because precise, close-tolerance casting eliminates most machining operations. Instead of using expensive brass, iron, and specialty steel castings or forgings, the IOSSO-ZN process puts conventional zinc die castings into contention to replace many of these expensive previously used alloys, the company says.

Another process developed by Iosso, the Iosso FE coating process, can be applied to all iron-based alloys, tool steel alloys, and stellite, as well as stainless steel, brass, bronze, beryllium copper, tungsten carbide, and Ferro-tic carbide. The coating is said to be well-suited for automotive, medical, aerospace, packaging equipment, food processing equipment, drive system parts, and farm and heavy equipment. Because of the company's expertise in handling critical, controlled tolerances and surfaces, an entire department has been set up for plastic injection molding. "We are experts at handling all surfaces up to optical," said Iosso. The FE coating process for injection moldings is reported to provide enhanced wear and extended life, providing customers with increased production time and less down time.

"In most cases, we double the life. When we engineer the job, we know at minimum we can double the life and, often, more than that. If the mold is running at a high efficiency, they don't have any down time between the parts coming out of the machine," Iosso said, explaining the importance of holding critical tolerances and surfaces. "So if they had to stop, they've got down time because they have to clean the cavity where it's sticking or it's wearing out. So these are critical things we work on in making that mold work longer, because when the surface wears down, that's when they start running into problems."

Both the ZN and FE processes are computer-controlled, chromium-based alloy coating processes for components or production wear parts. They are said to provide significant adhesion, a hard surface, and can penetrate some base metals by up to 0.000020 inch. The thickness of deposit reportedly provides critical tolerances in the range of 0.000020 inch to 0.00050 inch, and the coating is uniform over complex shapes and deep cavities with no buildup on sharp edges or corners, according to the company.

Primarily, the IOSSO coating processes benefit manufacturers who require parts to have increased hardness, extended wear, lubricity, and corrosion resistance. The coated surfaces are heat resistant, non-magnetic, crack-free, and static-free, with no peeling, flaking, or spalling. According to Iosso, the coating processes are anti-soldering and anti-galling, and do not cause hydrogen embrittlement of the base metal. "Our coating is key to holding critical tolerances; that is a very big plus," said Ortmann.

Both processes can be applied to parts varying in size from a 3/16 inch OD gear to a six-foot shaft. Production wear parts include gears, shafts, pinions, cams, rollers, valves, and pistons, as well as roll forming dies, blades, knives, cutters, slitters, and scissors. They also include molds, dies, cavities, cores, ejector pins, punches, cutting tools, and a wide variety of lock parts.

"By using a lower-cost base metal and applying the coating to cover it, you can reduce the cost by not using a premium metal and save money," Iosso said. "With both processes, you're extending the life of that metal and getting extra life out of those parts."