VSI Rotor Maintenance: Tip Replacement, Dead-Bed and Balance Checks

On a vertical shaft impactor, maintenance revolves around the rotor. If the whole tip set wears at the same pace, the machine is running well; if one tip thins ahead of the others, either the feed is reaching the rotor unevenly or the balance has been lost. In both cases the bearings end up paying the bill.

Rotor diameter and capacity in the GNR series

As the rotor diameter grows, so do capacity and the size of the tip set. The table also shows that the GNR 900, the largest in the series, is driven by two motors:

When should a tip be replaced?

Change the tip once the hardfacing on its back has worn thin, before wear reaches the parent body; wear that cuts into the body puts the rotor itself out of service. New tips always go in as a complete set, with weight-matched parts in opposite pockets.

Sticking to the feed size

Going above the maximum feed sizes in the table cuts tip life quickly and breaks up the dead-bed in the rotor pockets. Securing the feed size with a screen is the most economical maintenance a rotor can get.

Checking balance

If vibration does not settle after new tips are fitted, the build-up in the pockets may have formed unevenly. Clean the rotor and allow the dead-bed to form again.

The inspection round, step by step

First lock out and tag out the power (LOTO), then open the top cover. Tips, pocket build-up and the distributor plate are all checked in a single pass. If the dead-bed looks hard and equal in every pocket, leave it alone: this layer is part of the design and protects the body with the material itself.

How tip wear affects sand quality

A rotor turning on worn tips loses impact energy, so the share of fines falls and cubicity suffers. When the product curve drifts unnoticed, the cause is more often the rotor than the screen, which is why tip life cannot be managed without tracking the curve.

Points to watch on the twin-drive GNR 900

On a body driven from both sides, belt tension must be kept the same on each side. Extra tension on one side places an axial load on the bearing, and this shows up in vibration readings as a rise at a single frequency.

Three operating habits that extend tip life

First, keep the distributor plate centred; an off-centre plate sends material into one pocket and wears out that tip early. Second, set rotor speed for the target product: pushing speed higher than needed does not improve cubicity, it only consumes tips faster. Third, keep the feed continuous at a moderate rate; a rotor that fills intermittently loses its dead-bed each time it empties and leaves the body unprotected. None of these needs extra parts, only discipline. Record tip changes with date and tonnage, and after a few replacements the real wear-life curve for your model becomes clear.

One last tip: keep every part removed during rotor service (tips, pocket plates, distributor) tagged with model and date. A change in the wear pattern also reveals a change in the feed source; when the quarry moves to a new layer, the first warning usually comes from tip life.

Service intervals vary with the model and operating conditions. To put together a maintenance plan for your own machine, get in touch with us.