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Laboratory Tables & TableTop Platforms (continued) An effective table top design must incorporate three critical factors: mass, stiffness, and damping. Mass ensures that forces applied to the table top will cause minimal displacements. Stiffness raises the table top's lowest resonance out of the working range and provides a more stable work surface. Damping decays the higher frequency vibration that reaches the top. TMC provides three basic versions of table tops: stainless steel laminate, CleanTop ® II steel honeycomb, and granite. Stainless Steel Laminate. The standard TMC top plate is a 2 to 4 in. thick, highly damped, high stiffness lamination of steel plates sandwiched around a lightweight damped core, rigid epoxy-bonded into a seam- less stainless steel pan with rounded edges and corners. With their combi- nations of structural epoxies and visco-elastic adhesives, these tops will not delaminate due to heat, humidity, or aging. TMC laminated tops are recommended for most applications not requiring mounting holes. Laminated tops are standard on 64 Series TableTop Platforms, 65 Series Floor Platforms, and 63-500 and 68-500 Series Lab Tables, 63-600 ClassOne Workstations, and Quiet Island ® Sub-Floor Platforms. They can also be supplied with a plastic top skin laminated onto the stainless steel to make an even more easily cleanable surface. Plastic skins do, however, detract from the ferromagnetic properties of the top and are unsatisfactory for magnetic hold-downs. Steel Honeycomb CleanTop ¤ II. Increasingly, researchers are using honeycomb construction tops with their lab tables to facilitate bolt-down mounting of their equipment to a flat and stable work surface. TMC's spill-proof CleanTop II is uniquely suited to such applications. For a complete discussion of CleanTop II Optical Tops, see Section 2. Granite Tops. Granite surfaces are standard with 64 Series TableTop Platforms. They are available on special order with other isolation systems. The advantages of a granite top are its relatively high mass and stiffness and the potential for being lapped to a precise surface flatness. Granite's non-magnetic nature is useful in some applications. For small tops, granite is an inexpensive, moderate performance material. In larger sizes, however, granite is more expensive than standard TMC top plates, sacrifices damping, and does not have other desirable features. TMC Steel Honeycomb CleanTop ® II Top Plate Design Alternatives Small Lab Tables & TableTop Isolators Ferromagnetic stainless steel pan 0.075 in. (0.15 mm) thick with seamless, rounded edges and corners Single layer of soft bonding for additional damping Lightweight damped core for increased rigidity Steel plates for stiffness and mass Damping skin Epoxy 4 Technical Manufacturing Corporation 978-532-6330 800-542-9725 (Toll Free) Fax: 978-531-8682 sales@techmfg.com www.techmfg.com
1 5Technical Manufacturing Corporation 978-532-6330 800-542-9725 (Toll Free) Fax: 978-531-8682 sales@techmfg.com www.techmfg.com Damping Structural damping determines how quickly an excited resonance in a table top decays. The simplest way to measure damping is to hit the table top with a hammer and measure the decay with an accelerometer and oscilloscope or spectrum analyzer. The height of a resonance peak in the compliance curve also measures damping. Compliance Compliance is a reciprocal measure- ment of the dynamic stiffness of a table top. The data are obtained by inputting a measured force to the table top with a calibrated hammer and measuring the resultant acceler- ation (or displacement) with an accelerometer. Compliance is the ratio of displacement to force expressed as a function of frequency. Performance Summary Small Tops for Lab Tables Granite Top 30 x 48 x 4 in. (750 x 1200 x 100 mm) Damped Steel Plate 30 x 48 x 3/4 in. (750 x 1200 x 19 mm) Undamped Steel Plate 30 x 48 x 3/4 in. (750 x 1200 x 19 mm) Compliance Damping TMC Laminated Steel Top 30 x 48 x 2 in. (750 x 1200 x 50 mm) TMC CleanTop ® II 30 x 48 x 4 in. (750 x 1200 x 100 mm)
978-532-6330800-542-9725TollFreewww.techmfg.com, in.mmin.mm, in.mmin.mm, thenpositionedtowithinH110070.001in.in, in.mmin.mm, in.mmin.mm, 978-532-6330800-542-9725TollFreewww.techmfg.com,
www.publitas.com, www.publitas.nl
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