Metal Stamping Company Maintains Niche in Low-Volume, Deep Drawn Power Tubes

This technical information has been contributed by
Connecticut Coining

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Deep Drawn Parts
This deep drawn part for a medical application was originally made of bar stock stainless steel
The walls and the bottom of the part have different wall sizes Photo courtesy of Connecticut Coining

The medical industry is one of multiple high-tech markets for the precision power tubes

A metal stamping company in Bethel, Conn., maintains a special niche in the manufacturing world, one that has the company deep drawing custom-made, precision power tubes made with high-tech, exotic metals. The power tubes manufactured by Connecticut Coining (www.ctcoining.com) are often used for high-voltage, vacuum applications, including MRI and X-ray machines. They are also used in commercial and military radar and laser systems, and for power sources that drive telecommunication devices.

"The power tubes we make are used for any device that needs huge amounts of power," says Greg Marciano, the owner and president of Connecticut Coining. "We don't make the housings; we make the internal tubes that hold the electronic equipment. The materials most used would be pure nickel alloys and Kovar®, which have the same coefficient of expansion as glass and ceramic. The housings are usually built out of cast and machined aluminum, and are then lined with lead so that the X-ray or microwave energy can't escape."

For a variety of reasons, deep drawn power tubes lend themselves well to medical component applications. A tight grain structure is particularly important for parts used in the vacuum seal of the tubes used for X-ray machines, for example.

"Most of the tubes that that are used in the medical equipment are for high-voltage, high-vacuum uses, so they need to be deep drawn," Marciano explains. "If you machine the tubes out of bar stock, the material has inclusions and the grain structure isn't as tight as sheet metal, which doesn't have the inclusions. If you use machined bar stock in the high-vacuum applications, the parts could incur leaks. The deep drawn parts start out with sheet metal, and have a much tighter grain structure."

Due to the precision required, the majority of parts manufactured by the stamping company are produced in short to medium runs. "The tube industry is not a high-volume industry," Marciano remarks. "We also do work for the aerospace industry, where large volumes of these parts are not necessary. What makes our company [strong] is that a customer will send us a print, and our engineering department has the capability to figure out how to make the part more manufacturable."

An ISO-9001 certified company since 1999, Connecticut Coining is well-equipped to handle most part sizes, from small to large parts. The company has set aside a large section of the plant for its stamping presses -- about 50 presses in all -- from the smaller 10-ton presses up to the large 500-ton models. In addition, the contract manufacturer has a CNC machining department with 25 CNC lathes and mills, as well as wire EDM machines.

The deep drawing process stretches and extrudes a flat piece of metal using a die set, consisting of a die that holds the flat metal blank or partially formed part, and a punch that's used to push the metal into the desired shape. The deep drawn part cannot be made perfectly even due to the manner in which the molecules flow--guided by the die set--in the process of reforming the metal. Secondary CNC machining and finishing processes are therefore used to provide a customer with the tight part tolerances that are required.

Because of the crucial end uses for this type of work, tolerances are very critical to maintaining excellent quality. In this regard, the company handles material thickness from 0.003-inch to 0.250-inch, with deep drawing tolerances as tight as 0.002-inch and deep draw depths to 10 inches. Machining tolerances often meet or exceed 0.00025 inch, and surface finishes can be pushed to 8 micro inches.

Expediting production at Connecticut Coining is an on-site tool room, where its staff is able to build complex dies quickly and cost effectively. The company also has an extensive tooling library that covers a wide range of basic parts. Additionally, the company maintains a large raw stock inventory, which enables it to significantly lower tooling costs and provide rapid delivery of production and time-critical prototype parts.

Most of the high-tech industries that order power tubes require a very highly-polished part because the applications are inside a high-voltage environment. Any peaks, valleys, or burrs on the part, according to Marciano, could spark an electrical short.

For high-voltage power tubes, deep drawing has advantages over roll forming a tube and then welding the edges together, according to the company. "If you are going to roll form it, or use some other type of forming before the welding, the welding will have to be checked very carefully," Marciano emphasized. "You're going to need to X-ray the welds and test the part under vacuum conditions before it can be cleared to make sure the weld is leak-tight. You don't have to worry about any of this with deep drawn parts."

The stamping company specializes in short runs from 25 pieces to 25,000 pieces, as well as prototypes. Much of the company's work involves using materials such as Kovar®, Inconel®, stainless steel, tantalum, titanium, molybdenum, and assorted nickel-based alloys. Machining is often performed as a secondary process after drawing the tube to achieve the tight tolerances required.

"Our precision CNC machining for secondary processes gives us a competitive edge," says Marciano. "We also have a finishing department for the parts that have critical finishing specs. We outsource some finishing processes, such as electropolishing, plating, welding, and assembly, so a part is ready to go into a client's production line after it leaves here. The finishing work that we do in-house is usually mechanical work, like abrasive tumbling and hand polishing."

Marciano says that the company is able to handle these exotic, engineered metals because most production runs are small enough to allow staff members the time to perform a great deal of extra handling. This type of metal stamping doesn't compare to speedily processing a part with a progressive die, where parts are cranked out as quickly as possible.

"I've gone to a lot of tradeshows, and I don't see too many companies like ours that work with the exotic materials," says Marciano. "Some companies find it hard to deep draw these exotic materials, but we've got it down. We might have to inspect every single part and keep adjusting the dies while the work is in process, and we might have to polish the dies, as well. We could have an order for 100 parts and every part has to be checked, and even looked at under a magnifying glass after every press operation. This kind of work is very labor-intensive."

To create a tight seal for the power tubes, a ceramic or glass coating is often added to the tube. While the tube manufacturers will sometimes handle the glass coatings, the ceramic coating process is usually handled by a ceramic specialty house. "For example, when you make a glass seal for a piece of Kovar® for a vacuum, it's not fused," Marciano points out. "It's almost like welding it to the metal. When they use ceramic, they braze it and then put it in a furnace. The reason why it's compatible is because of the coefficient of [thermal] expansion between the metal and the ceramic. So they can heat up at the same time and cool down at the same time."

Connecticut Coining not only has a large marketplace in this country, but has clients located all over Western Europe, including Germany, the Netherlands, and France. To respond to these far-reaching locations, the stamping company has sales people in-house that are fluent in the German, Dutch, and French languages. In addition, Marciano will sometimes travel to Europe to meet with existing and prospective clients.

"The parts that the Europeans require are the same types of parts that we make for the American companies," he says. "Business, whether overseas or domestic, usually gets developed by word-of-mouth."

Greg Marciano's father, Greg Sr., started the company back in 1963, providing deep drawn and other types of stamped metal parts. Greg Sr. initially started working with a couple of companies, one of which was a Stamford, Conn., tube manufacturer that continued to send him more and more of its deep drawing work. Today, Connecticut Coining employs 48 people in a 30,500-square-foot plant in Bethel, a small town south of Danbury. One of the keys to the company's growth has been its ability to firmly grasp its customers' needs, then build on that understanding to provide design and engineering assistance for maximum manufacturability.

"In order to gain understanding of our customer's needs, it is important to develop a relationship with the customer that is strong enough for the customer to be comfortable allowing Connecticut Coining to understand not just what parts they need, but why they need them, the specifications they must meet, and how they will be used," says Marciano. "The best customer relationships are characterized by a sense of partnership between Connecticut Coining and the customer, which permits easy dialogue between our designers and engineers, and the customer's.

"We can help customers by seeing the parts that they are actually using," he continues. "They'll actually allow me to see their assembly area, or to take a look at parts in their stock room. I'm able to look at these parts and suggest ways to deep draw the parts if they're being done by machining. Instead of making the parts in two pieces, I will suggest that we make them in one piece."

New equipment recently acquired by Connecticut Coining has upgraded the company's quality control capabilities in a number of ways. "We just acquired a new piece of inspection equipment, an OPG, that's basically three machines in one," says Marciano. "It measures visually, and it allows us to inspect surface finishes; it can measure the depth and width of a scratch. It has a laser capability, which allows us to inspect many parts very quickly. It also has the CMM capability, which allows us to check angles and tapers that have to be measured. Therefore, if you put a part down on the plate after it's programmed, it can do all three aspects to measure the part."

In addition to expediting the company's inspection processes, the new machine has brought a higher level of measurement to the company. "It's accurate to a millionth of an inch, so we can do in-depth inspections on our parts," Marciano adds.

Connecticut Coining recently became certified by the International Traffic in Arms Regulations (ITAR) regulatory body that provides the U.S. government with information as to who is involved in specific manufacturing and exporting defense-related products.

"The ITAR registration has to do with safeguarding the customers' prints, and limiting access to our production areas," Marciano points out. "We decided to do this because one of our customers requested that we get certified, and also because you might not be able to do work for some companies without the certification, since it's becoming more prevalent. It's used quite a bit for military and military aerospace work."

This technical information has been contributed by
Connecticut Coining

Click here to find suppliers

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