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Special Designs are Built to Customer Specifications

Fennville, MI--- Metallurgical High Vacuum recently shipped two chambers for customer-specific applications. One vacuum chamber is over 72" high and will be used in P E. Chemical Vapor Deposition. The other chamber is a 12-inch square design that will be used to weld silicon sticks, complete with a two-stage booster vacuum pumping system. Both chambers are built of type 304 stainless steel for the demands of the applications.

 

Fennville, MI--- Metallurgical High Vacuum recently shipped two chambers for customer-specific applications. One vacuum chamber is over 72" high and will be used in P E. Chemical Vapor Deposition. The other chamber is a 12-inch square design that will be used to weld silicon sticks, complete with a two-stage booster vacuum pumping system. Both chambers are built of type 304 stainless steel for the demands of the applications.

"We are one of the best-kept secrets" in the vacuum business, Geoff Humberstone, MHV President, commented: Our capabilities range from new and rebuilt vacuum pumps and pumping systems to design and fabrication of chambers, piping, and custom designs. We built these two chambers for customers that knew us and wanted high quality and reliability."

"Chamber design for vacuum service can be tricky. For round cylindrical chambers, the ASME code can be used to size plate thickness. Rectangular chamber design is more difficult since the plates cannot be treated as thin shells; they have to resist internal bending moments."

"All chamber designs are deflection limited, i.e., we start out with a max allowable deflection- say in the range of 0.010" to 0.030". Plate thickness is determined by using this deflection and assuming a certain length-to-width ratio set by the proposed stiffening centerlines. Total loads into the stiffeners are then calculated.  There usually are significant end moments in the outside stiffening arrangement.  Deflections are calculated due to the uniform loading from the plates and the end moments.  After these are summed, a section inertia can be calculated to give the desired deflection.  The stiffeners are then sized by trial and error calculations to give the required section inertias."

The plates must then be press brake formed or rolled-up, by a shop which can hold extremely tight tolerances after forming.  In our shop, we do final plate trimming and weld prep so that fit-up is precise.  Good fit-up ensures dimensional accuracy, minimal weld distortion, and fast welding.

"Weld procedures are very important so we use TIG for the root passes with an inert gas backup to minimize weld scaling."  Geoff further notes:" We ensure full penetration welds by grinding down into the root pass from the opposite side.  Dye penetrant is then used to prove we have ground into the root pass.  Then additional TIG passes can be applied on the opposite side.  Finally, cover passes with a flux cored process can be used to get higher metal deposition rates.   Run out tabs may be required and are used to ensure sound weld right to the edge of the plates."

The machining is critical which MHV does using CNC when the chamber fits into a 46" cube or a manual horizontal boring mill for larger sections.  Door flanges are then polished for a good "O" ring seal.

Our vacuum leak testing showed that both of these chambers had background leak rates in the low 10-9 cc/second range, which is an infinitesimal 0.06 cc per year.   MHV tested each chamber blanked off and pumped down with a 1300CFM blower/300 CFM mechanical pump (Stokes 1722 package).   The final leak check was done using an Inficon UL-1000 helium leak detector.

Metallurgical High Vacuum has put their vacuum experience of over three decades on the line for their customers who depend on their vacuum processing systems 24/7 with reliability.

About Metallurgical High Vacuum

Metallurgical High Vacuum Corporation is a vital supplier in the vacuum technology industry. With over a quarter-century in the business, they have earned a reputation for responsiveness with high-quality engineering and manufacturing that is unsurpassed. Customers depend on MHV for keeping their operations running, and costs under control. MHV products and services include new and rebuilt pumps and systems, vacuum piping and manifolds, flexible connectors, vacuum valves, custom oil filtration systems, helium leak testing, and field repair. Rental pumps and blowers are also available; call to check inventory.

Contact us at 269-543-4291, Fax: 269-543-4750, E-mail: [email protected] to learn more.

Metallurgical High Vacuum Corp., 6708 124th Avenue, Fennville, MI 49408, United States

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