Non-Magnetic 710 Series

  • Overview +


    TMC's CleanTop® Optical Top, available in a "non-magnetic" construction, is recommended for applications requiring the support of a high-strength magnet or the maintenance of a homogenous magnetic field.

    Though no alloy of stainless steel can be 100% non-magnetic, the lower carbon content of the 300 series alloys offers a dramatic reduction in ferromagnetic properties. Alloys are available with even less ferro­magnetism than 304 alloy such as 316. For more information on the 316 stainless steel top, contact TMC.

     

  • The CleanTop® Advantage +


    All steel construction. No particle board sidewalls or plastic layer between top skin and honeycomb core. Assures maximum strength and structural integrity.

    Smallest core cell size, highest core density. The CleanTop design does not require enlarging the steel honeycomb core cell size because CleanTop cups are cylindrical, not conical as found in plastic layer designs. CleanTop's average cell size of 0.5 in.(2) is at least 50% smaller than that achieved with plastic layer designs assuring the highest stiffness and greatest core-to-skin bonding contact area

    Steel to steel to steel. CleanTop achieves a spill-proof core with only two bonding layers: top skin to core and core to bottom skin. Imitations must add a third bonding layer which weakens the structure: top skin to plastic layer, plastic layer to core, and core to bottom skin.

    Thermal stability. The CleanTop all steel construction assures materials of identical coefficient of thermal expansion ensuring optimal thermal stability. 

     
  • How to Select a CleanTop® Optical Top +


    1. Select Performance Series –

    TMC offers three levels of structural damping, though not all levels are available in each construction. Because the damping mechanisms are expensive to manufacture, it is prudent to specify only the level of damping required. All TMC damping levels incorporate broadband dry damping.



    Maximum Structural Damping – Research Grade:   
    TMC's maximum structural damping provides a level of performance unsurpassed in the industry. It is recommended for the most demanding applications.

    Standard Structural Damping – Scientific Grade:  
    An economical alternative for less sensitive applications incorporates our broadband standard dry damping level.

    Nominal Structural Damping– Laboratory Grade:  
    The nominal broadband damping level is appropriate for general lab work when the main consideration is a rigid, flat mounting surface.

    Select Specialty Series –


    ClassOne™ CleanTop®:  
    The ClassOne™ version takes CleanTop® one step further. Designed for maximum cleanroom compatibility, the ClassOne CleanTop has not only a stainless steel top skin but stainless steel sides and a stainless steel bottom skin as well. Nylon 6 CleanTop cups are standard and 304 alloy stainless steel cups are available as an option. Wiped down with a lint-free cloth, the ClassOne is wrapped in plastic prior to shipping and may be brought directly into a clean environment with minimal cleaning.

    Non-Magnetic CleanTop®: 
    For work in a highly magnetic environment, we offer non-magnetic construction. This table is made from 304 alloy stainless steel rather than the conventional ferromagnetic 400 series stainless steel. Though the skins, sides, dampers, and core are a 304 alloy, no stainless steel top can be said to be "100%" non-ferromagnetic. In some cases, 316 L alloy is preferable and this material is available.

    Vacuum Compatible: 
    TMC has combined our CleanTop® design with several new proprietary design features, cleaning methods, and a vacuum pump-down procedure to attain a level of vacuum compatibility previously unattainable.

     

    2. Select Table Dimensions

    Overall table length and width should be determined based on the best suitability at your location. Consider the space available, the size and mass of the items being placed on top of the table, as well as the overall mass of the entire system for installation purposes. Standard dimensions are available up to 5 ft. wide and 16 ft. long. Please contact TMC if a custom size is required.

    Overall Top Thickness A top length-to-thickness ratio of 10:1 is a safe rule of thumb for most applications, although for very sensitive work in severe environ- ments, a ratio of 7:1 may be justified. It should also be kept in mind that while top thickness is proportional to top static rigidity and dynamic natural frequency, it does not directly affect compliance, which is primarily controlled by structural damping. Standard optical tops are available in 8 in., 12 in., 18 in. and 24 in. Small, 2 in. (50 mm) thick tops should be supported on uniform flat surfaces, not post mounts. Our 4 in. (100 mm) thick tops may be supported on post mounts, but they do not incorporate the same proprietary damping techniques used on our thicker tops. We recommend that all sensitive work be done on tops at least 8 in. (200 mm) thick.

    3. Tapped Holes

    TMC offers both imperial 1/4-20 tapped holes on 1 in. centers and
    metric M6 tapped holes on 25 mm centers. Though there is no price
    difference between tops, imperial tops have imperial overall
    dimensions while metric tops have metric overall dimensions.
    The suffix designation determines the type of tapped hole, imperial
    or metric. In addition, we now offer both imperial 1/4-20 tapped
    holes on 1 in. staggered centers and metric M6 on 25 mm staggered
    centers, doubling the number of tapped holes on conventional 1 in.
    or 25 mm grids. The DoubleDensity™ construction is available
    with any version of our CleanTop® at a nominal additional fee.

  • 20 Reasons for Choosing TMC CleanTop® Optical Tops +


    TMC CleanTop®

     

    Competitive Construction

     


    TMC: Formed Steel Sidewalls

    Other: Particle board sidewalls


    TMC: Steel-to-steel bonding throughout 

     

    Other: Weak plastic layer separates core and top skin


    TMC: High stiffness, small cell size core, individual nylon cups

    Other: Less rigid, large cell size core; molded plastic cups



    1. Sidewalls of TMC tops are 0.075 in. (2 mm) thick, damped, cold-rolled formed steel (see center photo, above), unlike the moisture-absorbing particle board favored by other manufacturers, presumably for its low cost. In addition, steel provides structural integrity unattainable with particle board sidewalls.

    2.TMC’s design does not require enlarging core cell size because CleanTop cups are cylindrical, not conical like molded plastic membrane cavities. Our average cell size of 0.5 in.2 (3 cm2) is at least 50% smaller than molded cavity top designs, assuring the highest stiffness and greatest core-to-skin bonding contact area.

    3. CleanTop achieves a spillproof core with only two bonding layers: top skin to core and core to bottom skin. Imitations must add a third bonding layer, which severely weakens the structure: top skin to plastic layer, plastic layer to core, and core to bottom skin.



    4. Additionally, to avoid excessive epoxy being squeezed into the plastic cups, imitative designs use only the thinnest layer of epoxy between the top skin and plastic layer. The thinness of this layer can produce “voids” when the top is bonded by trapping air, significantly weakening the bond.

    5. TMC employs a proprietary process to clean our machined skins to a level that is virtually “sterilized.” This ensures the cleanest threaded holes and superb epoxy bonding. Furthermore, the cleaning station is in an entranceway to a clean, finishing building so that the cleaned top never sees a heavy, industrial machining environment. In the CleanTop® design, no machining, grinding or sanding of any kind is performed subsequent to this cleaning process.

    6. TMC top skins are stretcher-leveled, stress-relieved, and pressure-bonded against a precision-lapped granite plate, without subsequent grinding—avoiding heat and stress. The finished top is flat within ±0.005 in. (0.13 mm) within the entire tapped hole pattern, regardless of top size, guaranteed.

        
    TMC top skin (above) and competitive design top skin (below) after grinding.

     


    7. Top surfaces of TMC tops are lightly sanded with an orbital pattern to remove burrs and provide a non-glare, non-reflecting finish, without inducing internal stress.


    TMC no-glare surface (above). Ground surface of competitive design creates reflection and glare (below).




    8. Standard mounting holes in TMC tops are tapped, either 1/4–20 on 1 in. centers or M6 on 25 mm centers. Imperial 1/4-20 tapped holes on 1 in. staggered centers and metric M6 on 25mm staggered centers are available at a nominal additional fee. Custom patterns, including large through-holes for cables, etc., are easily accomplished with our multiple 2,000-watt laser machining centers.

    9. All TMC mounting holes are in register with open cells in the honeycomb core (a given with CleanTop® but not necessarily with other designs). This assures that the core is not damaged by subsequent drilling and tapping during manufacture, that the structural integrity of the assembly is maintained, and that all mounting screws can be inserted to full depth without obstruction.

    TMC registered holes (shown without CleanTop® cups.) (top), Competitive non-registered holes (bottom).




    10. Every hole in a TMC top is lead-screw-tapped, the most precise method known, and there are no inserts. Inserts can loosen, and top skins can be distorted when inserts are pressed into undersized holes.

     
    TMC countersunk holes (above) versus non-countersunk holes in competitive design (below)

    11. TMC mounting holes are slightly countersunk to remove ridges and burrs. Every TMC mounting screw can be finger-tightened at first insertion – no wrench is needed. 

    12. TMC’s broadband dry damping approach is the only logical one for an optical top. Others use "tuned" dampers which only work on a discrete frequency. Structural resonances are not discrete and therefore not eliminated but rather "split" into two resonances by tuned dampers.


    13. TMC’s honeycomb core is made of 0.010 in. (0.25 mm) thick steel, work-hardened and plated to prevent corrosion and assure years of service. Steel honeycomb is the ideal material for optical tops since the Young’s modulus of steel is three times that of aluminum.

    14. TMC’s honeycomb core is a closed-cell structure with basic cell size of 0.5 in.2 (3 cm2), giving a core density of 13-14 lbs/ft3 (300 kg/m3), significantly greater than others on the market. The effective core density is 18-20 (16 lbs./ft3) including sidewalls and dampers.

    TMC's honeycomb core. 

     

    18. Structural damping of TMC tops is accomplished using broadband mass dampers which are separate from the core, do not permit hysteresis or creep of the top, and do not detract from the top’s stiffness. 


    19.Our unique, direct core-to-top bonding improves the thermal conductivity of the core to the outside environment, reducing the "thermal relaxation time" for the top.

    20. Our skins, core, sidewalls and dampers are all made of steel and therefore have the same coefficient of thermal expansion. Thus, even in situations with repeated temperature cycling, a TMC top expands and contracts as a whole, assuring structural integrity and preventing long-term internal stress buildup.

  • Features +


    TMC's CleanTop Optical Top is the best method yet for providing a spill-proof, clean, precise, and corrosion resistant optical top with unmatched structural performance. CleanTop is now a standard feature of all TMC optical tops.

    Individual CleanTop cups are epoxy-bonded under each tapped hole after it is tapped and cleaned. Cups are made from chemically resistant nylon 6, and stainless steel (304 alloy) cups are available. Holes are now tapped and countersunk prior to adding the cups to allow the machined top sheet to be thoroughly cleaned with open, rather than blind, holes prior to bonding. The top plate is processed through a custom TMC industrial cleaning center where a high pressure, high temperature cleaning solution is forced through each threaded hole, completely clearing any machining or tapping debris. Several rinse and dry cycles ensure an essentially "sterilized" top surface prior to bonding the cups.

    CleanTop represents another innovation in TMC's long optical top tradition of industry "firsts" including:
    • First spill-proof optical top (CleanTop) 
    • First all-steel optical top 
    • First oil-free optical top 
    • First honeycomb core registered  to the tapped hole array
    • First lightweight breadboard with formed rather than drilled holes
    • First vacuum compatible optical top




    CleanTop features: 

    • Liquid spills on the surface are contained and cannot reach the top's honeycomb core.
    • The core is completely clean and dry with no residual thread-cutting oils to out-gas.
    • Extremely clean tapped holes make screw insertion smooth and simple.
    • Easy retrieval of small parts dropped into the holes is assured.
    • Since no penetration of the core is possible when dangerous chemicals are used on the top's surface, health hazards will not occur by chemicals reaching the core unnoticed. 



  • Performance +


    Structural Damping TMC has long adhered to the philosophy that dry damping of an optical top is preferable to oil-based dampers. Oil's characteristics can change over time and hidden oil reservoirs are always in danger of being pierced by an end-user customizing his system.

    Our approach to damping of structural resonances has consistently been based on a "broadband damping" approach. "Tuned damping," or using a tuned mass-damper to resonate out-of-phase with a top's bending mode, is a risky approach. First, it assumes the damper can be set to exactly coincide with the resonant frequency of the top. An optical top's resonant frequency will vary based on load, distribution of load, temperature, and even the presence of the dampers themselves. Therefore, in practice, it is difficult to tune the dampers to the top's resonance. Furthermore, it assumes that only the lowest resonant frequency requires damping when many secondary bending and twisting modes require attention.

    More importantly, the notion of incorporating a tuned mass-damper to suppress a structural resonance is a flawed one. Tuned damping is only effective in damping discrete resonances and is misapplied when used to damp a broadband structural resonance. In simple terms, a tuned damper "splits" a structural resonance into two resonances by creating a coupled mass system.


    TMC's proprietary broadband damping techniques are the most effective way to damp an optical top. This approach works over the entire frequency range of interest, dissipating energy at the top's primary, secondary, and higher resonant frequencies. In addition, performance will not be compromised by adding weight to the top.

    TMC's CleanTops are engineered using the most advanced methods for structural analysis and design. The Operational Deflection Shape shown above was measured using a technique called Laser Scanning Vibrometry (LSV). LSV is among the most sensitive and most accurate non-contact vibration measurement techniques commercially available. It uses the laser doppler effect to measure the behavior of the entire table rather than the behavior one discrete point. 



    Structural Damping Performance Summary TMC optical tops have guaranteed performance levels which are unsurpassed. In addition, with three levels of broadband damping and three environmental choices, TMC offers the most flexibility in choosing a performance level. Guaranteed maximum compliance levels for the maximum damping level are tabulated in the plots below. The standard damping level offers compliance levels a factor of four times higher than those tabulated. The minimum damping level is only recommended for non-sensitive applications. The curves summarize the guaranteed performance levels of TMC optical tops. In addition, table top corner compliance data are presented for the three damping levels available. Data were acquired by impact testing, using a one-pound calibrated hammer, accelerometer, and dual-channel spectrum analyzer. As these examples demonstrate, actual measured performance is often considerably better than our guaranteed performance. 

  • Specifications And System 1 Post-Mount Supports +


    Choose from Gimbal Piston Isolators or Rigid Supports –
    Micro-g® gives you superior convenience and economy in acquiring precisely the equipment you need for supporting optical tables or other large work surfaces. The unique Micro-g design lets you customize basic features and still have off-the-shelf prices and speedy delivery. There are six categories of options, and the convenient selection charts help you construct a part number for ordering. Systems can also be easily upgraded – whether to convert from a leveling stand to an isolator or add casters – whenever required.

     

    Options
    Isolators/Leveling Posts
    If you need vibration isolation now, the choice is our Gimbal Piston™ isolators, which are unsurpassed in the industry for passive vertical and horizontal vibration attenuation – especially as demonstrated at realistic, low levels of input.

    If a rigid stand will suffice for the present, Micro-g offers an economical leveling mount option with rugged, adjustable jack screws that provide +2 1/2 and - 0 in. (+62 and - 0 mm) of travel. Later, you can upgrade the system to full vibration isolation performance, with a total cost only slightly more than if you had opted for this feature originally.

    Load Capacities Depending on the weight of your table and onboard equipment, you can select support systems with capacities of 1,400, 4,000, 6,000, 10,000, or 15,000 lb (600, 2,000, 3,000, 4,500, or 7,000 kg, respectively). Customized systems can be configured from standard components to support virtually any structure.

    Height Seven post heights are available as standard: 12, 16, 18, 22, 24, 28, and 32 in. (300, 400, 450, 550, 600, 700, and 800 mm, respectively) – though not all sizes are available in all capacities. Taking into account the table thickness and height of equipment components, select the post size that provides the working height you need. Ergonomic convention would dictate 36 in. (900 mm) from floor to table top surface.

    Tiebars For safety reasons, tiebars are recommended. They are mandatory when you choose casters or anticipate upgrading to them. If you require constant access to the area under the table, free-standing support bases will provide more than adequate stability.

    Casters Micro-g's optional casters are of a rugged, heavy-duty design making an installed table easily movable when they are engaged. Once the table is positioned, the casters retract to establish solid floor contact during equipment operation. Like other Micro-g features, they can be integrated at the outset or purchased later if you choose to upgrade. Casters retract externally on the smallest capacity posts, internally on the intermediate, and are not available for the highest capacity. They are not available on posts less than 18 in. tall.

    Configurations A simple four-post frame configuration is the most common; however, depending on the size and shape of the supported structure and on the weight and position of onboard equipment, another multiple support system may be preferred. For unusual size tops or if you have any doubt as to your approach, please call us.

  • Accessories +


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  • Application Photos +


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  • Order Chart +