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Die neue MC 85 Grabenwalze (Mehrzweckverdichter) / The new MC 85 Trench roller (Mulitpurpose compactor)

MC 85 Trench roller / Grabenwalze

FAQ - Concrete Internal Vibrators

What are internal vibrators used for?

For compacting fresh concrete, within formwork or on surfaces.


Why is concrete compacted?

Depending on the consistency and supplement mixture (cement, sand, gravel, water), fresh concrete contains cavities filled more or less with air. The aim of compaction is to remove all of these cavities. With compaction the desired strength as well as rust protection and water impermeability are achieved.

Which internal vibrator is used?

Concrete internal vibrators heads are available in different diameters. Depending on the construction project, the appropriate head diameter is chosen.

Internal vibrators with a bottle diameter of, for example, 58 or 68 mm have a higher power and thus a higher effective diameter than 30 or 40 mm internal vibrators.
Small diameter devices are particularly suitable for compaction within formwork and/or tight-mesh reinforcement. Devices with a larger diameter are preferably used for compaction of concrete surfaces (floor slabs).
As a rule of thumb, the active diameter of an internal vibrator corresponds to approximately 10 times the diameter of the head.

Which models of internal vibrators does Weber MT offer?

We currently distinguish between two model series:
Internal vibrators with integrated converter (>> IVUR series),
-  Internal vibrators for which a separate converter is required (>> IV series).

How do I find the right internal vibrator or the right converter for an internal vibrator?

IVUR series internal vibrators are often used for small and medium-sized construction projects whereby the vibrator and converter are built-in-one. In other words, the electronic converter is integrated in the switch housing. The devices are complete and therefore ready for immediate use. IVUR internal vibrators are connected to 230 volts / 50 Hz alternating current.

IV-internal vibrators are driven by a separate frequency and voltage converter. The converter converts the input voltage (e.g. three-phase current 400 V / 50 Hz) into a protective voltage of 48 V and a frequency of 200 Hz.

Converter with multiple sockets are also available so that multiple internal vibrators can also be connected.

Please note the following:

  • The sum of the current consumption (amperes) of one or more internal vibrator must not be greater than the maximum current output of the converter. If a converter has two sockets and a current output of 34 A, up to two internal vibrators with a total current consumption of less than 34 A can be connected.

  • The output voltage (volt) of the converter must match the voltage of the internal vibrator.

How do concrete vibrators work?

A small electric motor (stator) is installed in the poker (bottle) of the internal vibrator. A shaft (rotor) with a centrifugal weight (imbalance) rotates inside the stator and vibrates the poker. This principle applies both to the devises in the IV series as well as to IVUR internal vibrators.

Weber MT concrete vibrators have an operating frequency of 200 Hz resp. 12,000 vibration / min. This frequency has proven to be optimal in the most common applications.

Tips for use

You can write an entire book on the subject of proper concrete compaction, so here are a few short tips:

The intervals with which the internal vibrators are immersed in the fresh concrete are selected so that the effective diameters (approx. 10 times the bottle diameter) overlap.

The internal vibrator is quickly immersed in the fresh concrete and pulled out again as slowly as possible. This gives the vibrator enough time to release the vibrations into the fresh concrete.

To compact concrete ceilings, the vibrator is immersed at an angle and then pulled through the concrete.

Touching the internal vibrator with the reinforcement should be avoided.

Fresh concrete that has been compacted well

  • will have hardly any air bubbles,
  • the concrete stops moving and
  • the surface is sealed with fine mortar (glossy).

Further instructions for use:

Do not let the vibrator run in the air unnecessarily: concrete internal vibrators are cooled by the fresh concrete during their use. In the air, they quickly reach temperatures of over 100° C.

The windings (stators) of Weber MT internal vibrators have winding class H and are temperature resistant up to 180° C. They are also equipped with thermal sensors. These cut off the power supply if the stator gets too hot. After a cooling phase, the device starts up again. To avoid constant switching on and off, the internal vibrator must be switched off when not being operated.

May 2020