A cutting method allowing for clean precision drives productivity forward

July/August 2012 - Many of today’s advancements are made possible when abstract concepts are applied to real-world applications. For example, acceleration occurs within a centrifuge, a piece of equipment that rotates around a fixed axis to separate substances. It’s often used for medical research and in the pharmaceutical industry. The pressure vessels, vacuums and chambers needed for devices like these are manufactured using tools that cut precisely and meet tight tolerances.

In Hollis, N.H., Hollis Line Machine Co. Inc. creates these components and an array of other parts spanning multiple industries. Hollis Line needs a method that leaves no heat-affected zone. As a result, using a waterjet is ideal when fabricating precision weldments out of stainless steel, for example, for the pressure vessel or vacuum furnace industries.

Investment in technological advances as well as facility and equipment upgrades have allowed Hollis Line to remain a staple for nearly 50 years in the Northeast manufacturing sector. It has an approximately 18,500-sq.-ft. facility. As the business grows, so too has the selection of parts Hollis Line provides its customers.

To meet customer needs, the company purchased an Omax 80X-1 waterjet from Kent, Wash.-based Omax Corp. The customized model allows Hollis Line to extend the machine’s standard 12-ft. table to 20 ft. long.

“We’re able to take a 20-ft.-long plate of metal and lay it on the table and can nest many different parts and cuts, minimizing waste,” says John Siergiewicz, president and general manager of Hollis Line. “We make cuts very close to each other and very little material is thrown away.”

Hollis Line needed the 50 hp, 60,000 psi Enduromax pump, the newest Omax pump on the market.

The company is able to cut 41⁄2-in. plate using Omax pumps. “We’re cutting it very efficiently and can get the part machined a bit faster,” he says, adding any remaining scrap is sold.

“They wanted the fastest cutting speed possible,” says Julie Kaiser, regional sales manager at Omax. “They do a lot of thick plate work, material over 2 in. thick, requiring a heavy-duty pump in order to achieve the best possible cutting speed.”

Hollis Line manufactures pressure vessels meeting ASME standards. It also holds the National Board R Certificate of Authorization R-5953 for repair and alteration of pressure equipment. The company is able to fabricate and machine new chambers or upgrade or repair existing chambers. Reaching a global customer base, Hollis Line also complies with the European Pressure Equipment Directive.

Expanding expertise

Over the years, Hollis Line has expanded the number of industries it services, including the fuel cell power generation industry, Siergiewicz says. “We have to make some precision weldments out of stainless steel,” he says. “[Some types] of compression fuel cells require little tabs, making it a very rigid structure, which welds up nicely.”

Working with various materials, including steel, stainless steel, aluminum, copper and nickel, Hollis Line offers parts for the semi-conductor industry. The company manufactures vacuum chambers for growing silicon crystals. To cool the chamber when silicon is crystallizing, a double wall is made from stainless steel. Another product, a stainless steel vacuum weldment, is produced from 403L stainless steel with two water jackets and two O-ring grooves.

The company produces cones by cutting a flat plate into a fan-shape and setting it in a set of rolls or a press brake. Workers make a series of bends to create a cone form, which is closed up by welding the seam until the cone is completed. “Then that [cone] becomes a pressure vessel, but having that waterjet enables us to cut a really precise shape,” Siergiewicz says.

Hollis Line also manufacturers pressure vessels 9 in. in diameter and 10 in. tall, 12-in.-diameter vessels standing 18 in. tall, 20-in.-diameter standing 22 in. tall and 28-in.-diameter standing 3 ft. tall, he says.

When cutting cylinders, Siergiewicz says Hollis Line uses the waterjet to cut penetrations into flat plate, which is then rolled up and welded. “The waterjet allows us to put in precise cuts and we put it in a set of rolls to set it in a cylinder,” he says.

More thicknesses, less water

According to Kaiser, the 80X-1 with the Terrain Follower accessory maintains a constant nozzle height over the material. “If the material happens to be warped, the machine automatically adjusts the height of the nozzle to protect the head so it doesn’t run into the material if the height changes,” she says. “Without that function, height changes could be a problem.”

Flexibility is necessary for Hollis Line to meet customer requests. “A customer can call me up and tell me they need however many pieces of 1⁄8-in. plate and 4-in. squares that need four holes at whatever dimensions and we can do it quickly on this machine,” Siergiewicz says.

The software component to the waterjet was important because Hollis Line works with a variety of different customers and products, Kaiser says. “Hollis needs to be able to introduce new designs and make revisions very quickly,” she says. “The software with this waterjet allows them to make changes quickly and get back to cutting within minutes.”

In New Hampshire, water restrictions are a potential problem. However, the Omax waterjet cutter uses substantially less water, according to Kaiser. “The Omax pump uses one water supply for both cooling as well as cutting,” she says. “Other machines often use two different circuits, one for cooling and one for cutting, thus drawing several times more water.” Using only one water supply makes the cutting process more efficient, she adds.

When making vacuum chambers, using a laser or plasma cutter requires cutting at high temperatures, resulting in some contamination of the material. Working with a waterjet cutter makes the cut without a heat-affected zone. Siergiewicz says otherwise it is sometimes necessary to run a vibratory stress-relieving process later to relieve any stresses in a weld, an extra step that costs valuable time.

“Before beginning the welding of a vacuum chamber, the welder would have to grind away the heat-affected zone caused by the laser cutter,” he says. “If a plasma was used, it might have to be milled [afterward], which is time consuming. You need a waterjet to get a really good weld so you don’t have to do that.” FFJ

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