The Gateway - Featuring Omni Components
Screw Machining: Advances in Auto. Bar Machining

The Gateway - Featuring Omni Components
The Gateway
By Bill Bryson
February, 2002

Omni Components Corp.’s quality policy is: “To provide superior quality products and services in a timely manner, to fulfill the needs and expectations of our customers.” It goes on to say, “Our primary goal is customer satisfaction. Each member of the Omni Components’ team is responsible for ensuring that internal and external customer requirements, expectations, and needs are met. Every employee is to be involved and committed to pursue the principles of excellence. We achieve this by improving processes, methods, and working environment to insure that each customer is receiving the highest quality product at committed costs, on time.” This policy statement is on display throughout the facility and is visible to all who visit Omni.
Omni Components Corp. started in 1978 in Hudson, NH in a converted chicken barn. Today they are in two facilities with 50 full-time employees with plans on the board for a brand new facility, which will house the company under one roof.

Their customer base is widespread through the medical industry, instrumentation, optics, electronics, communications, and commercial high tech. Founded by William (Rick) Holka, President, Omni specializes in precision components. The company has 25 Citizen CNC Swiss Multi-Axis lathes, many equipped with high pressure coolant, bar loaders and the ability to produce completed parts straight off the machines. With the capability to mill, drill, tap, all within the turning environment in diameters up to 2 3/4” and chucking up to 8”, they can produce quantities from prototype to hundreds of thousands of pieces.

If given a preference, Omni chooses to become involved during the engineering concept phase for process simplification resulting in potential cost savings to customers.

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Supported by 4-axis vertical milling machines used to perform primary or secondary operations, CNC water jet cutting, high speed Fanuc Robo drilling, and a multitude of support equipment, Omni is in an excellent position to offer high quality parts to virtually any manufacturer.

Quality is a vital and intricate part of Omni’s success. Omni is ISO9001:2000 certified. Their quality staff is knowledgeable, trained, and active to ensure machining accuracy is maintained throughout the operation. Omni offers SPC, if customer required, and all parts are thoroughly inspected from first piece through final to assure perfect parts go to the customer.

Omni works with many customers towards turnkey operations, offering grinding, finishing, heat treatment, or whatever is necessary to produce the part for one-stop shopping. They offer JIT and Kan Ban replenishment programs, lean manufacturing, and will carry raw material stock in anticipation of customer needs on critical parts. They are developing with some customers an auto-replenishment system where e-mail messages will arrive from automatic bin control systems, via radio control to notify Omni that parts need to be replenished.

Charles Doherty, General Manager, does the quoting and is heavily involved with sales and his sales reps. He is often the first contact within Omni, and will bring Rick or the Engineering department into the discussion to develop the right approach to the machining need. Based on the collaboration of the team, the quotation will be made.

In response to our question of what Omni would like to say to potential customers, Rick responded that, “Omni cares about customer success and has the talented people who are committed to production and service. We understand that when our customers are successful, we are successful” Charles’ response was, “We offer total customer satisfaction and we live up to our Mission Statement, because it is what this company is all about. Perfection is our aim. Integrity is the foundation of our values, and compromise is never an option.”

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Screw Machining: Advances in Automatic Bar Machining

By Mark Shortt and David Gaines
JobShop Technology Magazine
Eastern Edition, August 2001

While reducing setup times and secondary operations, CNC Swiss Automatics produce parts that are superior with respect to both dimensional tolerances and surface finish.

Manufacturers who are looking to find a screw-machining source shouldn't have to look very far. In the U.S. today, screw machining is reported to be a $2 billion industry that delivers precision parts for everything from watches, heart implants, fiber optics connectors, and solenoids, to aerospace fasteners, photo imaging devices, and automotive drive shafts, sensors, and brake systems. Employing technology ranging from single-spindle, cam-driven machines to multiple-spindle, CNC Swiss Automatics, more than 6,500 job shops regularly turn out precision-machined miniature screws, connector pins, and other small-diameter parts, as well as valves, pinions, bushings, and tubular parts with internal threads.

It’s a good thing, too, because manufacturers are being driven more and more to outsource screw machine work by factors related to corporate business strategy, economic necessity, and technical expertise. While many are realizing the need to concentrate more on core competencies, such as product development or marketing, they are also finding it increasingly difficult to hire skilled, competent machinists to operate increasingly complex and expensive equipment. Others are inclined to outsource complex parts, or jobs requiring materials that are difficult to machine, such as high-temperature alloys.

 “Screw machining” is a general term for a process used to manufacture a wide assortment of pins, connectors, shafts, bushings, nuts, bolts, and valves, as well as various screws and other intricate threaded parts. It encompasses turning operations by a number of different specialized machines, including automatic and semiautomatic types. Cam-operated, single- and multi-spindle machines, CNC single-spindle machines, and automatic lathes, or chuckers, are among the different types of screw machines widely employed by job shops.

 Automatic screw machines, also known as automatic bar machines, use an assortment of tools attached to a special turret. With the tool attachments, a number of different operations—such as milling, broaching and cross- drilling, tapping, and slotting—can be performed on the screw machine. Automatic screw machines can turn workpieces from 1/16 inch to 6 inches in diameter, and are capable of high rates of production. Parts can be machined from 12-ft-long bars using automatic bar feeders, and thousands of parts can be made with very little variation in size, notes Grob. Single-spindle machines usually have one spindle with five tools, while multiple-spindle machines have anywhere from four to eight spindles configured in a circular arrangement, with each holding a separate workpiece. 

Swiss-type automatic screw machines are prized within the industry for their ability to provide high precision, holding tight tolerances with great repeatability. CNC Swiss Automatics, programmed to handle both primary and secondary operations on one machine, can produce parts that are superior with respect to both dimensional tolerances and surface finish “for really no extra cost,” according to Greg Cde Baca, president of Pacific Swiss & Mfg. Inc., Clackamas, Oregon. 

“The best advantage of using CNC Swiss screw machines is their ability to produce complex parts extremely accurately, usually to 0.0005 inch over several inches, or longer,” says Cde Baca. “By using CNC Swiss screw machines, we find that with the technology that the machine tool builders are putting into the machines and the after-market accessories that are available, we are only limited, in what we can make, by our own creativity.”  

 Jack Graeber, president of Northwest Swiss-Matic, Inc., a QS-9000-certified shop in Minneapolis, Minnesota, says that CNC Swiss machines are the most appropriate equipment for today’s fast turnaround, precision machining. “Ideally, we want to do the close tolerance turning and milling work on the CNC Swiss machines,” comments Graeber. “The large form tools on the multi-spindle machines can remove large amounts of material faster than the small, single point cutter on the Swiss machines. But we get tighter tolerances, better concentricity, and nicer finishes from the CNC Swiss machines. We can hold +/- 0.0002 inch on the Swiss machines, depending on the type of material, part configuration, and length of the part.”

Screw machining permits the consistent, high-volume production of components with tight tolerances (usually 0.0005 inch or less), says Tom Hicks, vice president, ALCprecision, Farmingdale, New York. According to Hicks, the process still offers a minimal capital investment in custom tooling compared to other technologies with “hard tools,” such as die casting, powder metallurgy, or metal injection molding (MIM). It also provides a shorter turnaround time and lower tooling cost for part modifications and design changes. “You can make a lot of design changes with screw machine parts before you are faced with purchasing new ‘hard tooling,’” commented Hicks. 

Advances in Screw Machining Technology

By expanding opportunities for cutting operations, the multi-axis, CNC Swiss turning machines reduce the number of separate secondary operations required and decrease overall cycle times. The CNC machines also require shorter setup times and provide “very respectable part-to-part reproducibility, even on close tolerances,” says Hicks. From a quality perspective, optical vision inspection arrays work with computer measuring systems to permit complete inspection of critical dimensions in real time. As a result, nearly instantaneous corrections can be made to the turning process.

Many of the technological advances in screw machining center around the use of CNC control technology, according to Rick Holka, President of Omni Components Corp., Hudson, New Hampshire. “PC-based, open architecture, Internet-capable CNC controls provide tremendous possibilities to the industry,” Holka says. “An example would be the ability to ‘rent’ a particular control feature for a specific job via the Internet, as opposed to having to ‘buy’ the feature as part of the capital investment in the machine. Another advantage would be real-time, online help with troubleshooting and maintenance.”

A major advancement in CNC Swiss automatics has been the development of the rotary guide bushing, according to Ron Grob, president of Ron Grob Company, a screw machine shop that employs 25 people at its 16,000-sq-ft facility in Loveland, Colorado.

The advance led to the incorporation of various types of insert tooling, which enabled higher surface footage while holding close tolerances and concentricities. Also, the development of multiple axes with live tooling also greatly enhanced the capabilities of Swiss automatics, Grob added. “Now, a sub-spindle with full C-axis can be used to pick off a part and perform several complex operations while another part is being started on the main spindle, resulting in a faster cycle time,” he noted.

But according to Grob, the greatest strength of a Swiss automatic screw machine is also one of its greatest weaknesses. The length of the guide bushing (about ¾ inch on larger machines) limits the length for making multiple passes on a turn, Grob explained. Although long, slender parts can be turned in one pass, the removal of large amounts of material (1 ¼-inch down to ¼-inch diameter) is a slow process, he said.

The process is also better suited to some parts designs than others, according to Hicks. “Geometrically speaking, radially symmetrical designs benefit most from turning operations,” Hicks says. “And conversely, ‘free form’ geometries are best produced either with straight machining operations (general machining centers) or net shape technologies such as casting, molding, stamping, or compression forming (powder metal or ceramics).”

Solving Problems for Manufacturers

ALCprecision has a 150-year heritage, dating back to Samuel Laubscher’s first automated Swiss screw machine. The company, part of the American Laubscher Group of companies, specializes in miniature and micro-sized parts and manufactures a wide range of custom miniature screws, connector pins, contacts, shafts, and terminal ends for the medical/surgical, automotive, consumer products, and communications technology industries.

“We provide high-precision parts which are only slightly larger in diameter than a human hair, but with complete profile geometry,” says Hicks. “From the very beginning, we have been focused on small parts, first for the watch industry, and then evolving into tiny precision components for computers, automotive controls, and now electronics and wireless communications. Our machines are specialized to manufacture in these small sizes, and our material handling processes are set up for small parts, too. This involves everything from the special handling of wire-thin raw material, to special capturing methods on the machine which prevent the parts from mixing with the larger chips.”  It also includes special plating and surface coating equipment that is designed, in some cases, to coat parts so small that 12,000 of them are able to fit into a common sewing thimble, Hicks explained.

In addition to manufacturing small parts (under 10 mm diameter), the company can provide larger parts, up to 25-mm diameter, “with micron-sized tolerances,” Hicks says. ALCprecision has had success in working with difficult materials—such as 316L, beryllium copper, titanium, and ARCAP—and parts that require demanding secondary operations, like plating, heat treating, or grinding. The company can also successfully run high volumes of close-tolerance parts, handling quantities “in the millions and often tens of millions or more,” according to Hicks.  

 “We have a small, stainless steel pin which is used in surgical applications for joining severed nerve endings, veins, or arteries,” Hicks noted. “These pins are only 1.71 mm (0.067 inch) long, with a shaft diameter of 0.16 mm (0.006 inch), and have a head diameter of only 0.35 mm (0.014 inch).”  According to Hicks, the pins permit surgeons to reattach the severed ends up to 10 times faster than with standard techniques, thereby decreasing the time during which the patient is in surgery.

“The challenge for the screw machining operation was to make parts this small and then to handle them so they do not get lost in the process,” Hicks commented. “The concept for specialty machines used for making parts this small comes from the early days of Swiss screw machining. These machines are smaller and far more precise than standard machines available on the market. We now manufacture these pins by the thousands in regular mass-production quantities.”

Omni Components Corp., Hudson, New Hampshire, provides CNC multi-axis Swiss, CNC multi-axis turning and milling, and CNC multi-axis vertical milling services to customers in the instrumentation, medical device, optical device, and communications industries. The firm’s customers require precision, multiple-feature components that are often complex, for use in medical tools, implements, and implants, optical lens assemblies and housings, fiber optic components, routers, and switching equipment. Certified to ISO 9001:2000, Omni also produces a variety of precision components used in commercial applications for valves, actuators, assemblies, and specialized machinery.

The company has obtained greater efficiency and faster cycle times by integrating the use of high-pressure coolant (2000 psi) and high-speed spindle (60,000 rpm) technology into the equipment used for turning and milling. According to the company, the technologies permit more accurate manufacturing of difficult, complex components on its CNC multi-axis Swiss lathes, multi-axis turning centers, and multi-axis vertical milling machines. By providing chip control at the tool tip, high-pressure coolant technology contributes to cleaner, faster turning, drilling, and milling operations, and extended tool life. The technology also allows for “through-the-tool coolant,” which permits cleaner and deeper holes and milled features. Omni uses high-speed spindle technology in place of conventional mechanical spindles to perform micro milling and drilling of components in any orientation to axis. The technology is said to provide fast, accurate removal of most metal materials and can assist in substantially reducing cycle times.

Omni recently put these capabilities to use on a job involving components for a manufacturer of fluid dispensing equipment. The small, close-tolerance, stainless steel components required stepped through-holes from 0.015-inch diameter down to 0.0035-inch diameter. Omni’s challenge was to produce clean, burr-free orifices with the greatest possible yield on tool drills, while not compromising quality or cost.

This was accomplished on Citizen Multi-Axis CNC Swiss machines by adapting high-speed drilling spindles and precise spotting techniques to face drill the required through-hole combinations, Holka explained. Opposed drilling and main spindle rotations of up to 35,000 rpm permitted effective surface footage for the drilling of these small holes. High-pressure coolant (up to 2000 psi), directed along the drill through a special drill collet, keeps the drill tools free of chips and helps maintain a cool temperature at the tool/work piece interface. “All objectives were met, including requirements for milled features on the OD of the components, as well as off-axis, backside face drilling of blind holes,” said Holka. “The process has been a success and the customer has expanded this line of product as a result.”

Ron Grob Company performs screw machining for manufacturers in many industries, including electronics, medical devices, energy production, fiber optics, hydraulics, semiconductors, and after-market automotive parts. Customer products range from aortic punches, to pool cues, printed circuit board in-circuit test fixtures, mass flow valves for computer chip manufacturing, and fruit peeling equipment. Because the company has in-house thread rolling capabilities, it makes many parts from thread-rolled rods, which it custom rolls to its customers’ thread and material specifications.

Diameter tolerances of  +/- 0.0001 inch with a surface finish of 8 rms are not uncommon, and a total tolerance of 0.0005 inch is held on a daily basis, Grob says. “We hold a length tolerance of  +/- 0.005 inch on parts up to 100 inches long,” he asserts. “When we can’t hold diameter and finish tolerances on the automatics, we usually can do it on the grinders.”

Pacific Swiss & Mfg. Inc. employees 11 people at its 5000-sq-ft facility and has plans to expand in the near future, according to Greg Cde Baca. At peak time, the firm runs its six-machine CNC Swiss department approximately 125 hours per week.

“Our customers are in the connector, electronics, high-tech, medical, dental, telecommunications, hardware, and automotive industries,” says Cde Baca. “They produce anything from miniature connectors to medical/surgical equipment. Parts are generally of complex shapes or difficult-to-machine materials, such as nickel, Haynes alloy, and Hastelloy, among other alloys. Our customers primarily outsource their complex parts, or hard-to-machine materials like the high-temperature alloys that other shops do not have the capability to make or do not want to run.

“We offer a full range of capabilities with CNC Swiss Automatic screw machines. All are state-of-the-art, from Citizen, from the 2-axis B-12 through the 7-axis L-20 and L-25. By utilizing right angle heads and NSK air spindles on both the front and back workstations, we can be very creative on how we manufacture complex parts.”

Northwest Swiss-Matic manufactures precision screw machine parts for customers in the automotive, medical, electronics, and military industries, among others. Quantities are often large, with orders ranging up to 100,000 parts per day. Critical-tolerance metal spools and pistons, manufactured for leading companies in the automotive, hydraulics and pneumatics, and aerospace industries, are examples of precision components produced by Northwest Swiss-Matic. The firm produces individual parts ranging in size from 0.010 inch to 23/4 inches, with lengths to 3 feet. Some parts require accuracy to ± 0.0002 inch.

Northwest Swiss-Matic is certified to MIL-I-45028, MIL-I-45622, and the intent of MIL-Q-9858, in addition to QS-9000.

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