Vibracon® SM Frequently Asked Questions

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General Questions... What is a Vibracon® SM element? How long have Vibracon® SM elements been in use? Who is Machine Support ? What are the benefits of Vibracon® SM elements? What is more cost effective: Vibracon®, steel chocks, epoxy resin chocks or shims? Where can we use the elements? Do we need special skills or tools to use the elements? How do we order Vibracon® SM elements? Technical Questions... Is it possible to chock a heavy machine on a Vibracon® SM element? Which size of Vibracon® SM element do we need? Can we lift a machine with a Vibracon element? How do we prevent the element from rotating? When we want to use fitting bolts, how should we do this? When we want to use dowel pins, how should we do this? Are there any limits to the chock height? What to do if we want to have elements with extended height? What to do if we want to have elements which are lower then the minimum height? Is it possible to enlarge the bolt holes of the Vibracon® SM element? Marine Application Questions... Is the Vibracon® SM element approved by classification societies? What information is needed to make calculation and a sketch of the chocking arrangement? What bolt torque should we apply?   General Questions Top   What is a Vibracon® SM element? The Vibracon® SM element is an universal adjustable steel chock. Universal refers to the fact that a Vibracon® SM element can be used instead of rigid steel chocks, shims or epoxy resin chocks. Adjustable refers to the possibility of aligning and re-adjusting the element every time when required. The name of the element "Vibracon" suggests that the elements can absorb vibrations like a vibration damper. We want to point out that the Vibracon® SM element is absolutely not a vibration damper. How long have Vibracon® SM elements been in use? The design of the elements is based on products which are used to mount tool machines. In 1988 Machine Support designed the nowadays Vibracon® SM elements and in the same year applied for a patent. The Vibracon® SM elements are approved by all major shipbuilding classification societies and a large number of machine manufacturers. Who is Machine Support? Machine Support is the specialist on laser alignment and mounting of machinery on board of ships and in industrial environments. In basic Machine Support is a service company but also sells all the products which it uses in performing alignment jobs like: laser alignment equipment, shims, epoxy resins and of course Vibracon® SM elements. Due to the experience in the field Machine Support is able to provide customers with sound advice for all kinds of alignment and mounting jobs. What are the benefits of Vibracon® SM elements? In packaged units (like generator, compressor, turbine and pump sets) the benefits are: No parallel or angular soft foot problems, even when the skid is twisted No more machining of the base frame No on site problems to arrange or install shims Always re-adjustable In combination with laser alignment equipment, alignment time can be reduced by 50% On board of ships for chocking propulsion units or auxiliary equipment: No hardening time like epoxy resin chocks No time consuming fitting of rigid steel chocks Chocking can be carried out when ship is still in the dry dock. Only alignment check and (if required) realignment has to be carried out after the ship has been launched. No parallel or angular soft foot problems, even when foundation is not machined No machining of foundation, only local (where the elements will be fitted) machining if required. What is more cost effective: Vibracon® SM elements, steel chocks, epoxy resin chocks or shims? This question depends on the type of application. In most of the applications the Vibracon® SM elements will be cheaper because of: Reduced chocking time Always a perfect fitting chock No soft foot problems Installing of the Vibracon® SM elements doesn't require special skills or tools Usually no machining of foundations or base frames is required Where can we use the elements? We recommend the installation of elements for all rigidly supported machines or in combination with resilient mounts (depending on the configuration of the resilient mount base plate an additional plate may be required). Examples:   Diesel genset     mainly under the generator   Steam/gas turbine set     under the generator and gearbox   Compressor set     under the driver (E-motor or diesel engine)   Pump set     under the driver and/or pump On board of ships in propulsion units or auxiliary equipment Examples:   Diesel engines     Turbines   E-motors     Compressors   Gearboxes     Generators   Pumps     Winches   Complete sets     Shaft bearings In production plants the elements can be used under all kinds of rotating equipment, and also in production lines which need accurate alignment. Do we need special skills or tools to use the elements? Special skills or tools are not necessary to use Vibracon® SM elements. Machine Support advises you always to contact your local dealer or Machine Support for support during the first time installation of the elements. Also ask for the installing procedure. The use of laser alignment equipment is recommended but not necessary. How do we order Vibracon® SM elements? Vibracon® SM elements are always on stock Machine Support in the Netherlands. However it is recommended to check the delivery time before ordering. The local dealers of the elements also have some elements on stock. A list of all the local dealers is available.   Technical Questions Top   Is it possible to chock a heavy machine on a Vibracon® SM element? On a Vibracon® SM element in general three forces are working: Fweight due to gravity Ftorque due to the fact that the machine wants to rotate Fbolt due to the tightening torque of the foundation bolt Fbolt is approximately 6 till 10 times Fweight and even 10 till 15 times Ftorque. This means that Fbolt is the critical force on the element If we consider for example the Vibracon® SM30 element we can see that we are tightening a M30 bolt against a M95 bolt (internal bolt size of a Vibracon® SM30). It is easily to understand that the Vibracon® SM element can't be damaged by the machine forces unless the element sizes are wrongly calculated or the foundation bolts are insufficiently tightened. Which size of Vibracon® SM element do we need? In general we advise you to follow the machine designers opinion on the size of foundation bolts. If for example an E-motor should be secured with a M36 foundation bolt then just use a SM36 Vibracon® SM element. It is of course always possible to request a detailed calculation of the size of elements. Machine Support has special computer software for calculating the element size and bolt data. Can we lift a machine with a Vibracon element? No, the elements are only meant for chocking! For lifting the machine hydraulic tools or jack bolts are recommended. When the weight of the machine is pressing on the element it will lock itself automatically due to friction in the thread. How do we prevent the element from rotating? The Vibracon® SM element will lock itself (due to friction in the thread) after the foundation bolts are tightened. It is not necessary to lock the element in any other way. The copper fixing bolt in the element is only to prevent the element from turning when a machine is dismounted for maintenance or repair. When we want to use fitting bolts, how should we do this? In general it is not necessary to ream also the Vibracon® SM element. Reaming only the foot of the machine and the foundation usually will do. In some situations (for example in case of trust forces on a marine gearbox) we also advise to ream the Vibracon® SM elements. Please contact your local dealer or Machine Support for extra advise on this matter. Figure 2.1 General arrangement for a fitted bolt When we want to use dowel pins, how should we do this? After the alignment and the securing of the foundation bolts, weld down a block of steel (which is just 1 mm. lower than the elements), near at least one of Vibracon® SM elements or between two elements. Drill a hole through the foot of the machine into this block. Now the dowel pin can be installed.   Figure 2.2 Alternatives for a dowel pin application Are there any limits to the chock height? Yes, there are limits to the standard elements. Please check in the table on the Vibracon leaflet the minimum and maximum height of each type of element. When designing a chocking arrangement please have a look on the nominal height of the element. What to do if we want to have elements with extended height? In this case it is possible to use a bottom ring with an extended height (contact Machine Support or your local dealer). The maximum height of the element should not exceed the diameter of the element. Figure 2.3 Vibracon® SM element with extended height What to do if we want to have elements which are lower then the minimum height? It is allowed to reduce the elements to a minimum reduced height which is mentioned in fig. 2.4. Reducing the height can be done in a lathe by machining the center and bottom part of the element. Keep in mind that the adjustment capabilities will be reduced. At the minimum reduced height you will have only 1 mm. adjustment capability! NOG TE DOEN!!!!!!!!!!!!!!! Figure 2.4 Vibracon® SM element with reduced height Is it possible to enlarge the bolt holes of the Vibracon® SM element? For this you always need approval from Machine Support and classification society. It is allowed to enlarge the bolt hole of the elements in accordance with the following table:    Type        Bolt        Enlarged bolt hole (mm)     SM12 M16 17 SM16 M20 21 SM20 M24 25 SM24 M30 31 SM30 M36 37 SM36 M42 43 SM42 M48 49 SM48 M56 57 SM56 M64 65 SM64 M72 73 Please contact you local dealer or Machine Support to make a calculation of the bolt torque and the recommended clamped length.   Marine Application Questions Top   Is the Vibracon® SM element approved by classification societies? Yes, the element is approved by all major shipbuilding classification societies. Although, it is always necessary to submit a calculation and a sketch of the chocking arrangement for approval for each application. This is mainly necessary for propulsion units and for some societies also for auxiliary equipment. Contact your local dealer or Machine Support for assistance. What information does Machine Support need to make a calculation and a sketch of the chocking arrangement? The following data is requested: General   Yard or owner name Ship name or new building number Classification society Type of object Make / type   Machine   Mass Power Revolutions Foundation width between bolts Number of elements Diameter of the existing bolt holes Additional information when it concerns a gearbox:     Reduction rate Average distance between bolt holes Difference in height between outgoing shaft and foundation Propulsion efficiency   Drawing   Foundation plan Chock height Thickness of machine foot Thickness of foundation Plan for fitted bolts Plan for steel end chocks What bolt torque should we apply? For marine applications all classification societies have different opinions on how to calculate the bolt torque to be applied. Please contact Machine Support or your local dealer to assist you with calculating the required bolt torque. Top