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Minnesota Firm Making a Name in Precision Machining and Vacuum Brazing
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The CEO of a company that produces close-tolerance machined components and vacuum brazed assemblies discusses his firm's unique capabilities for solving manufacturing challenges.
Lakeville, MN - DHY Corporation is a QS-9000-registered and ISO 9002-certified manufacturing company whose name is an acronym for the custom-machined Die Head Yokes that the firm used to produce for automatic screw machines. Since its founding in 1978, the firm has achieved much success and no longer commercially produces the component for which it is named. Today, at its 53,000-sq-ft facility in Lakeville, Minn., about 25 minutes south of downtown Minneapolis, DHY Corporation manufactures precision machined components and vacuum brazed, complex assemblies for the aerospace, automotive, and medical industries, as well as various commercial customers. The firm's vacuum brazements are currently in use on the F22 Raptor Advanced Tactical Fighter, the Joint Strike Fighter, and the F18 Hornet, as well as other high-performance aircraft. For the medical industry, DHY produces parts used in spinal implants.
Through the years, DHY has earned many awards for meritorious service from customers, the U.S. Small Business Administration, and the office of the Governor of the State of Minnesota. Even the U.S. Senate recognized DHY with a flag flown over the U.S. Capitol in honor of the company's work rendered in defense of the nation. But according to Kendal Owen, CEO of DHY Corporation, the awards tell only part of DHY's story.
"More important than all the placards is the recognition given to us by our OEM customers, who have many times down-selected DHY as their supplier of choice from a field of scores of potential suppliers around the nation to supply them with very difficult parts and assemblies," said Owen.
Recently, Owen shared with Design-2-Part Magazine (D2P) some of his insights on DHY's work for the aerospace/defense and other industries. Following are excerpts of comments that Owen provided in writing to D2P:
D2P: For what types of aerospace/defense products does your company provide design or manufacturing services that involve parts, components, or assemblies?
KO: Currently, DHY provides primarily manufacturing services, with limited design services, to a variety of defense and aerospace customers. We produce liquid and air-cooled heatsinks for advanced fighter aircraft and for ground-based vehicles which utilize sophisticated, high wattage-generating electronics. We also provide the liquid and air-cooled chassis and racks. Both the individual components and assemblies require a great deal of precision machining, vacuum brazing, pressure-drop testing, and burst testing prior to being shipped to the assembly lines. The materials vary from standard aluminum alloys to exotic composites.
DHY also machines an array of electronics "packages" from various materials, like AlBeMet and aluminum, for missile defense systems. In addition, we machine certain components for Thermal Weapons Sight Systems and conventional firearms.
D2P: What design or manufacturing processes/services do you provide in support of these projects?
KO: As a supplier/partner to many OEMs, we provide strategic assistance in designing for manufacturability. This usually requires early supplier involvement with the engineering personnel at the design stage. This service can provide tremendous value in that it reduces certain costs not only in the final manufacturing process, but can also eliminate 're-engineering' the part/assembly at a later date in order to make the manufacturing process cost effective.
DHY provides prototype and production machining services - both vertical and horizontal milling, turning, and wire EDM. We provide vacuum brazing services in house, which can greatly reduce costs and enables certain "impossible" designs to become feasible for manufacturing.
We also provide for our customers all the necessary testing for flowage, pressure drop, and burst testing, where applicable, on certain avionics and vetronics parts and assemblies, along with all the information archived on discs and accompanied with full FAIRs and/or PPAPs.
We provide metallographic services to verify joint strength and integrity of vacuum brazed assemblies. We also offer our experience in managing a large supplier base per QS9000 standards, complying with all requirements regarding traceability of materials. Some of our products specify an array of plating and painting requirements on the same part. These requirements for finishes such as nickel cadmium, gold, BR127 epoxy, specified epoxy paint finishes, and special anodizing demand attention to masking and a host of sensitive processes. As the prime contractor, we have to provide the education and supervision to ensure total compliance to our customers' specifications. We have developed that experience over the years.
D2P: What types of materials do you work with on these manufacturing projects?
KO: DHY machines the following metals from wrought stock, castings, forgings, and extrusions: all aluminum alloys, magnesium, aluminum-beryllium (62% Be, 40% Be, and 30% Be and BeCu, only 2 to 3% Be), titanium, brass, all standard steel alloys, including Stainless Steel.
We also machine plastics - DuPont Teflon (PTFE), nylon, phenolics, and glass-impregnated phenolics - and occasionally we have machined 100% beryllium and ceramics.
D2P: What are some of the biggest technical/engineering challenges - involving design, materials, or processes - associated with the types of manufacturing projects that your firm accepts from aerospace or defense equipment manufacturers?
KO: Since we do not design the products we produce, our most difficult challenges in the area of design are related to designing tooling, fixturing, and processes which will produce finished components to spec. Many of our customers require and design monolithic parts, which means the parts cannot be machined in sub-units and brazed or assembled to form a completed part. The part, therefore, has to be completely machined from the initial billet or block of wrought stock. When a substantial amount of stock is machined away and only 5% to 10% of the original part mass remains, the remaining structure has been subjected to many stress forces, both inherent in the original stock and imposed by the manufacturing process. This can result in a number of distortions to the finished product. However, many of these parts require very precise finished geometric features wherein flatness and squareness, for example, are specified to a close degree in a free-standing state.
This represents a challenge which has to be overcome utilizing a combination of fixture design, machining processes, and sometimes intervening stress relieving processes, such that the finished product meets the customer spec. DHY has the experience to overcome the challenges we face in designing fixtures, tooling, and processes that produce the end results stipulated by our customers.
Some of the materials challenges we have faced and overcome have had to do with either the reaction of certain materials to the machining and/or vacuum brazing processes or with the associated safety issues. Ascertaining the most efficient cutting tool configurations in addition to the speeds and feeds for brittle metal, such as Be or AlBeMet, proved to be a challenge to us several years ago when we initially began to work with these materials. We also experimented with various program paths for the cutting tools, which also proved to be beneficial once we began to gather data on both the tool life and the effects on the metal when cut from different directions.
The challenge of solving the problem of machining certain types of metal without inducing stresses in the host material was finally overcome by experimentation, trial and error, data collection, and analysis of the quality data associated with each type of machining process. In addition, some of the materials we work with present safety issues which had to be overcome to ensure the safety of all personnel. For example, magnesium and titanium present a fire hazard which has to be prevented or efficiently handled once it occurs. We have been able to do this through research and a careful, methodical approach to our fabrication procedures throughout the entire production processes.
One of the most difficult and costly process challenges was solving the difficulty of consistently brazing AlBeMet in a vacuum. After a few years and several hundreds of thousands of dollars, we were able to develop a sound and robust process which consistently produced the kind of product our customers desired. Largely as a result of this DHY pioneering breakthrough, Raytheon Corporation awarded us their Supplier of the Year award in 2000, and DHY became the supplier of certain strategic, mission-critical components for advanced fighter aircraft.
D2P: What are some of the industry specification standards to which your work is asked to comply?
KO: QS-9000, ISO-9000, ISO -14000, GMP, AS-9100, and MIL-C-7883. Also AWS-2750, AMS-2720, AMS-2658, MIL-I-6870, MIL-B-20148, QQ-B-655C, and AWS-5.8.
D2P: What are some of the innovative or unique aspects of the manufacturing methods and technology utilized by your firm?
KO: Documented Continuous Improvement is a mandated condition of QS9000. DHY has consistently demonstrated this type of plant-wide improvement to systems and procedures, as is evidenced by our unbroken record of being officially certified as a QS9000 facility by independent ENTELA auditors, who have routinely analyzed our facility for many years.
Unfortunately, the term, "Continuous Improvement," has become so prevalent that it has become a "buzzword" in the industry to which, regrettably, some manufacturers have paid lip service without backing up their verbal homage with diligence and substantive changes to their work practices.
I will mention only two of the various areas in which we have tried to continuously improve. One is price reduction and machining quality improvement through investments in state-of-the-art flexible automation and "lights out" manufacturing. The other is internal software development, such that all business is conducted online (60 interactive databases with varying levels of access), reducing time and materials consumed in virtually every phase of the business.
These databases not only save huge amounts of time when accessing files but also ensure that all appropriate personnel are on the same page regarding such things as revision levels and work instructions. Since all new information is real time and therefore immediately available to all concerned personnel via both manual and automatic e-mails, any misunderstanding or confusion as to old or outdated information is eliminated. Transactions of any kind take place in seconds rather than minutes and save time and money, enabling us to remain competitive and ahead of the curve.
DHY personnel have been continually updating and expanding the use of this online system as part of our Continuous Improvement Process.
D2P: What are some of the advanced skills or expertise that the company's personnel utilize while manufacturing parts or providing services for these products?
KO: There are a number of advanced skills and expertise exhibited by a good number of our personnel in the area of tool design and CNC multi-axis programming for our precision machining operation. However, one of the areas of expertise demonstrated here at DHY that people are not commonly aware of is the process of vacuum brazing aluminum/beryllium and the accompanying metallographic analysis and flow testing.
As far as we know, DHY was the first machining facility to ever successfully braze aluminum/beryllium on a consistent basis, such that the finished product passed and exceeded all customer specifications in the avionics or vetronics industry. We developed and utilize special processes that were never part of any other company's processes when they attempted unsuccessfully to produce vacuum brazed components from this material.
D2P: What are some examples of tolerances that your company can achieve with your processes?
KO: When most people talk about precision machining, they tend to think of precision in terms of tolerances. DHY has made parts with dimensions that are toleranced within ± 0.000010-inch. We routinely machine production parts that have to exhibit dimensions with tolerances of ± 0.0001-inch (one ten thousandth of an inch). We provide the customer with precision machining where necessary.
However, whenever anyone speaks about precision machining and close tolerance work, a number of factors have to be considered: the size of the part, the inspection standard, and difference in degree of difficulty between prototype and production machining.
To hold a dimensional tolerance of ± 0.0001-inch on a milled part is relatively easy if the part is only two inches long. However, if the part is 36 inches long and the linear dimension between features is 34 inches, for example, then the tolerance of ± 0.0001-inch becomes much more difficult to produce and to maintain (given the thermal expansion of the part of just a degree or two Fahrenheit). In short, the closer the machined features are to each other on any given component, the easier it is to maintain a close tolerance dimension.
If a blueprint requires demonstrable Gage R&R studies with greater than 20% capability and a CPK ratio of 1.33, or 1.66, then the tolerance becomes statistically harder to maintain. If the truth be told, most manufacturers whose machines are incremented in 0.000040-inch cannot hold this tolerance in production due to a number of factors, such as thermals, tool wear, tool pressure, machine consistency, and multi-operator inconsistencies in loading and checking parts. Once the processing of parts is introduced to accurate, comprehensive metrological analysis, most processes are nowhere near as accurate as the manufacturers advertise.
Also, it is relatively easy to CNC machine (and certainly to grind or lap) a few parts to within ± 0.0001-inch. However, if the customer's purchase order demands 1,000,000 parts per month or per year, then the tolerance requirement becomes much more difficult. The machining process, over time, is subject to many more variations than it would be exposed to during a short amount of time devoted to a prototype part on which usually one person using the same inspection tooling is working.
Once many people are required to load a part, check a part, and run the part during the daytime, then the evening, in high- and low-humidity conditions, the variations in the manufacturing process become apparent even if they are manufactured in a "temperature controlled" environment with spindle chillers and sophisticated equipment that is capable of diagnosing and "remedying" its own internal thermal conditions.
D2P: What other services do you offer that would be of interest to a manufacturing engineer or purchaser?
KO: In addition to prototype-through-production conventional milling (both horizontal and vertical) and turning of castings, forgings, extrusions and wrought materials, DHY offers pre-manufacturing engineering for cost reduction; wire EDM; vacuum brazing; metallographic analysis; and flow testing and pressure testing of a wide array of heatsinks and chassis containing both fluid and air.
We also offer various heat treating processes; assembly; supply chain management of multiple sources, including casting facilities, forging facilities, extrusion houses, platers, and other suppliers. DHY has ISO9002/QS9000 certification plant-wide on all processes, and we use multiple CMMs for in-process and final part inspection, accompanied by full FAIRs and PPAPs that are provided to our customers on CDs.
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