Form Vibrator:

Form vibrators are also known as external vibrator. It is fastened to the formwork by a clamping device and transmits vibrations to the concrete. External vibrator is clamped at a distance up to 25 cm in depth from the formwork. The vibrator must be firmly clamped to the form as otherwise its efficiency will be reduced. The formwork should be suitably strong and rigid to resist the oscillatory action. The time of vibration is from 45 to 90 seconds. The vibrator is switched off for 5 minutes after its continuous working for half an hour in order to allow cooling of motor. If the motor of the vibrator heats up more rapidly, the work should be immediately stopped. The electrician should be called in order to check the motor winding. In this case, more power is required in comparison to internal vibrators. Therefore, emergency vibrators must be kept near the concreting work as replacement for vibrators, which go out of order. Form vibrators are used in concreting of thin components of monolithic structures, heavily reinforced arches and tunnel and tunnel lining, etc. They are also used in the production of different pre-cast reinforced concrete components.