Shop Solutions: Going Deep with a Four-Way Valve
National Coupling Company Inc. (NCC; Stafford, TX) has developed hydraulic coupling technology for oil and gas production systems requiring high-reliability subsea components since the early 1980s. Today, the company has more than 300 US and foreign component patents granted.
NCC primarily produces hydraulic couplings for critical applications, including designs for extreme highpressure/high-temperature environments. As oil and gas production goes deeper and deeper in the oceans, the need for systems to operate reliably in extreme environments poses new challenges and opportunities. NCC owns many of the patents on metal-seal technology, which is particularly effective in extending service life and reliability when operating in conditions of higher pressure and temperature.
As part of its diversification strategy, in 2006, NCC introduced a chemical injection system for subsea applications. The chemical injection system is plugged into subsea distribution systems to introduce high-value ($1500 per gallon) chemical cocktails into the well. When correctly and precisely injected, these chemicals extend the life of existing wells and maximize the production of a finite resource. Chemicals incorrectly injected into a well can cause collapse and shut down the well's production capability.
To control the rate of chemical injection, the system uses positive displacement metering to provide precise control and verification of chemical injection rates without the use of flow meters to a maximum depth of 15,000' (4572 m), 17,500 psi (121 MPa), 350°F (177°C), and at flow rates ranging from 1 gal/day to 2 gal/min (3.8L/day to 7.6 L/min).
A complex four-way valve is at the heart of this system. NCC began to search for ways to shrink the lead time for manufacturing the valve, which then ranged from 16 to 18 weeks. NCC approached Mori Seiki USA (Rolling Meadows, IL) with two boxes of 12–14" (305–356 mm) material, a four-way-valve prototype, and a copy of the print for the part. The challenge presented to and accepted by Mori Seiki was to determine the right machine or machines to manufacture the four-way-valve in an hour's time.
"At that point, we didn't have the expertise or the time to get up to speed making the valve," explains Ken Oberholz, NCC vice president of operations. "It would have taken us 10 to 18 months to get into production on our own to source the right machines, develop the applications, and complete prototype testing. We needed to be in production in less than six months." Mori Seiki and Ellison Technologies jointly set out to develop a project plan for machining the valve. Initially, it wasn't clear if it could be done or how many machines it would take to produce the valve in less than an hour.
NCC, which has been employing "lean manufacturing" principles since 2002, is a make-to-order (MTO), engineer-to-order (ETO) company. With over 2800 coupling designs, each week the manufacturing line must produce 1500 coupling assemblies involving 60 to 80 product famifacilities," says Oberholz. The machine or machines selected by Mori Seiki needed to keep with this philosophy.
NCC's production system allows them to have six coupling assemblies come off the production line every 10 min. They have taken a very complex part, with 68 to 95 value-added production minutes, and reduced each manufacturing operation to less than 10 min while using six to eight machines to produce each part. "With setups reduced to less than 5 min, we can maintain a high-velocity, high-variability production line," says Oberholz.
Oberholz has to be able to turn a machine over quickly and run a large variety of parts. NCC tries to eliminate total waste, so all time is value added. With this concept, they are always making the right parts at the right time, and everything is driven by customer delivery. It allows NCC and Oberholz to be very flexible on what parts they are providing.
This same methodology is central to developing the equipment used to manufacture the four-way-valve. "Our customers know if something goes wrong on their end, we can respond quickly. In an emergency, we can drop a coupling order in the front of the line and 90 min later they're in assembly, and that's without interrupting production," says Oberholz.
After review of part and print-material requirements, Mori Seiki's and Ellison's joint application engineering group selected a Mori Seiki NT4300DCG with a 100-position tool changer. The NT Series with DCG (Driven at the Center of Gravity) technology is capable of high-speed, heavy-duty, and high-precision machining of all kinds of materials. NCC was further impressed by the fact that Mori Seiki and Ellison Technologies backed their decision with a no-risk guarantee that the machine would completely produce the parts.
The solution involved using one NT4300DCG machine to make a valve in less than an hour. Three months later, the first trial runs were completed in Chicago at the Mori Seiki USA Center. The first run yielded a part complete with all operations, but the internal finishes and some close tolerances needed to be refined. In five months time, the NT 4300 was producing its first production run at NCC. The results were 10 for 10 for production. Some of the valve's critical details include:
- Fifteen sealing surfaces require finishes of 8 and 16 rms.
- Tolerance requirements are from 0.0002 to 0.001" (0.005–0.03 mm).
- There are 58 tools required for 145 operations and 125 critical dimensions.
- All deburring is done on the machine with no secondary operations needed.
- The valve is produced from bar stock in 68 min.
In addition to producing the four-way valve, NCC gave Mori Seiki and Ellison Technologies a list of four other parts that would have to be machined on the selected equipment. "With the versatility of the NT4300, we're also producing SPM [subplate mounted] valves and shuttle valves that are used in subsea drilling systems and incorporate the latest advances in our patented technology," Oberholz reports.
"With the NT, we are able to turn all the large workpieces we need for the chemical injection system, as well as produce the smaller components required in the valve assemblies. When you actually look at it, you wonder how someone even thought the four-way valve up, let alone how you will manufacture it," remarks Oberholz.
"Each year we set out a goal to improve all our critical measurements by 50%," says Oberholz. "We currently outsource 17% of our manufacturing, and we look for opportunities to reduce that number each year as we bring on new product lines."
The NT4300DCG and the four-way valve was the first project NCC developed with Mori Seiki and, since then, the company has used the same process to define its requirements and improve efficiencies by acquiring a Mori Seiki NZ2000T3Y3. "With these machines, we are beginning our journey to lights-out manufacturing and further reducing our cost of operation," Obherholz concludes, and he looks to the future growth of his company through its relationship with Mori Seiki and Ellison Technologies.
Ultrasonic Machining Improves Productivity
Ultrasonic machining of various glass ceramic composites, like Zerodur, has significantly improved productivity for the ASML Optics Group (Richmond, CA).
The facility supplies the parent company, ASML Netherlands B.V. (Veldhoven, The Netherlands) with a variety of components used in its advanced systems and equipment for the semiconductor industry, including wafer stepper and scanner machines.
ASML manufactures lithography systems for manufacturing integrated circuits (ICs) or chips used in computers, TVs, mobile phones, bank cards, and MP3 Players. The company designs and fabricates optomechanical systems and subsystems and optical component fabrications, including flats, prisms, spheres, and complex aspheres, and does glass and ceramic machining.
"The significant improvement in the shop's productivity stems from the recent addition of new ultrasonic machining equipment supplied by DMG America Inc. [Schaumburg, IL]," says Matthew White, ASML Optics manufacturing manager.
Zerodur from Schott North America (Elmsford, NY), is an extremely expensive raw material with the properties required for the high-accuracy applications of the semiconductor industry. The machinery produced by ASML is used by semiconductor manufacturers in their critical lithography operations to image circuit patterns in photoresist on silicon wafers in the chip-production process. A new ASML technology, Twinscan, images one wafer while simultaneously measuring the next one. The parts produced from Zerodur by the ASML Optics Group must attain consistently uniform tolerances, less than 10 µm.
ASML has machined glass materials for years, but concluded that it needed to increase its productivity without sacrificing the extremely tight tolerances held in its machining processes. Often, the prototyping process at this facility leads quickly to a production run once the prototype has been found suitable for the application. Given the difficulty in machining Zerodur, an entirely new approach was required, one that would provide fast material removal while maintaining superior accuracy.
The ASML Optics Group reviewed a number of technologies and other ultrasonic machine tool suppliers before deciding upon the Ultrasonic 50 and Ultrasonic 70 machines. The two machines offer the flexibility for either three or five-axis machining in both ultrasonic and conventional milling-machine modes.
Each of these machine tools features the Sinumerik 840D Powerline CNC from Siemens Energy and Automation (Elk Grove Village, IL). The 840D CNC provides the capability for quick programming and setup in either machining mode. In the ultrasonic mode, the CNC's adaptive control and acoustic control features combine with its open-architecture design to monitor the machining action and quickly adjust the feed and spindle speeds to maintain predictable accuracies to the desired levels.
Adaptive control monitors the process forces on the machining tool, while the acoustic control registers the intensity of the tool vibration on the workpiece surface via an electrical echo signal, as well as the status of the coolant pressure. Special HSK 63-S tool fittings on the DMG machines facilitate the changeover from conventional milling to ultrasonic machining mode.
In DMG's ultrasonic machining technology, the machining spindle creates an oscillation that causes the diamond tool to pulse with a controlled frequency between 17,500 and 48,000 Hz, depending on the spindle type used. This action removes microparticles from the material surface at a rate approximately five times faster than conventional machining, especially on such advanced composite materials as Zerodur.
According to DMG's Erich Bertsche, the permanent gap between the tool and the workpiece leads to significant reduction in the heat stress and the work force required, thus conserving the tool life and the workpiece material integrity. An inductive spool that functions as the transmitter is affixed to the tool interface underneath the spindle head. There is another spool on the HSK 63-S fitting that functions as the receiver. As a result of the ultrasonic stimulation, the diamond tool kernels contact the workpiece surface with a controlled force, thereby removing the material in a precise and predictable manner. Much like the spark gap in an engine, the ultrasonic stimulation causes the diamond kernels to smash into the workpiece in micronic particles that "sculpt" the surface.
In the semiconductor industry, this machining technique is frequently used to work silicon, silicon carbide, silica glass, and glass ceramic composites like Zerodur, holding tight dimensions with surface finish to 0.2µm or better being the standard.
"Our group works in various advanced material compositions," says ASML's White. "The challenges of Zerodur, as well as other materials, required us to look for a new machining strategy to maintain our manufacturing standards while continuing to supply our parent company with the necessary part production. We saw substantial upsides to the DMG Ultrasonic machines, and continue to find new and better ways to use them for the improvement of our overall process here at ASML. These machines have simply ramped up our productivity by a factor of five, compared to the previous technology we utilized." DMG also supplies the special tooling needed to machine Zerodur.
Bertsche explains that his company employs a special Sauer galvanizing and sintering process to create the diamond tools for ultrasonic machining. Through this process, a special binding matrix keeps the diamond kernels precisely in place during continuous tool oscillation.
ASML does its own programming on its ultrasonic machines. In this effort, it uses one benefit of the Siemens machine-control technology, namely, the swivel cycle. "We set up the origin of the part, and the swivel cycle allows rotational shift of the coordinate system, X,Y,Z transitional, with no separate work offsets needed. Where once we needed four setups over three machines, we can now perform two setups on one chuck on one DMG machine," White says.
As part of the Siemens ShopMill suite, the swivel cycle has a menu-driven feeler function for determining the zero-point offset, even in swiveled five-axis machining planes. It allows flexible input of the swivel angles in a workpiece coordinated system, including axis angle, solid angle, and angle of projection. Thus, both the programming and the setup time are reduced. For a job with a lot of oneoff or small batches made from extremely costly materials, this feature further expands job potential, while substantially speeding up throughput.
Bertsche also notes that the HMI developed by Siemens has resulted in faster training on the machines, by using standard M-code actuation of the ultrasonic on/off, standard ISO code, plus the onboard adaptive and acoustic-control programs. The DMG setup of all parameters is done seamlessly as another window within the standard Siemens CNC screen array.
Essentially, the concept of open architecture on the Sinumerik 840D CNC enables the machine builder to program its own functionality into the NC kernel. "The machining process is continuously monitored, making untended machining possible, even in the high-precision, small batch runs. As an example, intelligent control algorithms typically regulate the feed rate while machining an inside radius," says Bertsche.
The Siemens control recognizes these contours, and automatically adjusts the feed rate to maintain correct cutting conditions. Also, with the touch of one button an ASML operator can call up the ultrasonic generator screen and all variables can be quickly adjusted, including ultrasonic frequency, and amplitude and output, or the operator can automatically adjust the output for a defined number of tools in the ATC.
High-Velocity Part Production
A 75-employee job shop, GSP Components (Rochester, NY) started out as a screw-machine shop in 1951—one of the earliest pioneers in machining exotic alloys on screw machines. In the early 1980s, the company recognized it was necessary to evolve from a single-spindle turning and milling machine shop to shape its future as a fast-responding parts supplier to aerospace and automotive customers. GSP started working with Hardinge (Elmira, NY), acquiring its first turning machine installed in 1984.
Today, GSP's specializations include production of accurate prototypes and small/ large-lot parts supported by engineering services, problem solving, and value-engineered cost savings. Currently, the company is running 27 CNC mills and 56 CNC lathes—most of which are Hardinge units. It machines many aerospace parts from materials like Inconel, Hastelloy, and other exotic materials. Complex parts are machined on its Quest multiaxis turning machines with Y axis.
Ron Motsay, owner and president, measures GSP's success by the velocity with which product moves through the plant: "Some shops calculate their job processing by no one handling the parts and having the machine do all the work, whereas I come from the mindset of converting raw material into finished goods with high velocity. This frequently means using more spindles in the shortest time possible. It's all relative to how you look at numbers. Velocity of part production doesn't mean having an expensive machine do all the work. You can machine the part expensively with nobody touching the part, or you can make the part inexpensively with more people touching the part. That's how we calculate it out."
The result is a lean operation. When visitors to GSP Components look around the shop, they don't see any parts or stock lying around. The parts are made and the parts get shipped. Motsay states, "I think many shops fall in love with their machines and not their entire process. The hardest thing about running a velocitybased plant is not what happens in the machine when you load stock. Anyone in the country can do that."
GSP Components focuses on getting the product into a shipping box that same day or the next morning. "We put our finished goods right by the offices at the front of the building," says Motsay. "As we get further away from the offices the complex process becomes less of a constraint. As a management team, we like to have our constraining processes near where we work. It helps us support and monitor how we are performing throughout the day."
At GSP Components, stock comes in through the back dock and works its way through the shop to the front of the building from where parts get shipped, unlike many shops whose shipping dock is far from the offices. This keeps GSP's management team right at the core of the operations. Stock is brought into a lean environment one to two days before the materials are needed. The machine operators use kanban material tags and pull systems as a bar-stock ordering system. Some of the parts are finished complete on one machine, while others require more operations. Either way, products for that day get transferred to the wash area, and any additional machining gets done the next day.
"Material movement happens really fast, but not without quality checks and gaging of the parts. Nothing is more important than part verification and ensuring that specifications are met," says Motsay. "If we have a relatively simple part that is a rush order, we'll almost always run it on one of the seven Quest GT gang-tool lathes. It's a fast, easy way to go."
Motsay explains: "Today, we had a rush order from the same customer for two different parts, 100 pieces each, and the best and fastest machine for the parts was the Hardinge gang-tool lathe. We're able to maximize our throughput on these machines due to their interchangeable top-plate capability. For annual orders, say 3000 pieces, we can quickly turn out 100 pieces as the customer requires them. We have fifteen back-up tooled plates with each holding two or three jobs on them. Plus, we have extra top plates for our CHNCs lathes as well. Fast setups like this allow us to work around the issue of needing to run, say, a minimum of 300 pieces to maximize throughput on a different machine."
GSP has the ability to match the part to a machine's capability for process efficiency. Once that's determined, most of the velocity and the management of customer requirements comes in the next process, whether it's cross-drilled holes, milling, profiles, and the like. The variety of Hardinge lathes that they have to pick from allows GSP to pick the correct machine right from the start.
"Another way to look at it is that we have the machine to suit the part," says Motsay. "If that machine is tied up, we'll step the part down to the next best available Hardinge machine. We look at throughput when quoting a job. It's not a cycle time issue, but what machine we have available in our arsenal that'll get the product through the door with the highest velocity."
Utilizing high velocity methods has allowed GSP to reduce its inventory dollars. "As we reduced that expense, we worked with Hardinge to reinvest those dollars into capital investments in Hardinge machines," says Motsay. We take pride in our machines so they look and run like new. We only run oil-base coolants for best tolerances, finishes, and tool life. A machine operator may run three or four machines, depending on the workflow. We decided to stay the course with Hardinge because our workers know the machines, the controls, the tooling, and the methods. They're all the same. Hardinge has a good name in my book and I think that's pretty well agreed to throughout the Northeast."
Donna Cobertt, lead person and programmer, who runs the CNC shop floor, was instrumental in transitioning and training some of GSP's screw machine operators over to the Hardinge turning centers. Their Brown & Sharpe and Davenport workers were able to take their skill set and commit it to CNC technology. Cobertt requires that any new machine have a Fanuc control so that there's a common platform for programming. "This way the programs are interchangeable. It's easier to train people, and easier to get jobs on and off the machines due to the commonality of programming," she states.
Toward the front of the shop, there are two rows of VMCs. According to Motsay, "We need many spindles in a row for throughput, and we have outfitted all of them with Hardinge rotary tables. I bought GSP Components 12 years ago, and made the decision early on to manage our process, not allow the process to manage us."
In 2005 GSP purchased an outdated screw-machine shop down the street. Since then, it has pretty much sold off all the old screw machines, and replaced them with more Hardinge lathes. "We keep growing every year," says Motsay. "Last year brought us to just over $10 million in sales. It's the Hardinge machines and what we've been able to do with them that allows us to remain competitive and responsive. There's a lot to be said about loyalty. Hardinge takes care of us, we take care of them. It's a win-win situation."
This article was first published in the May 2009 edition of Manufacturing Engineering magazine.