Smooth Double Roll Crushers are normally used as Secondary & Tertiary Crushers where narrow spectrum ot grain analysis is desired, i.e. with given setting say "S" Most of the product gains lie near to "S". Reduction Ratio less than 1:4 and rolls can be set to 0.5 to 0.8 mm. Feed size, setting & roll diam are to be so selected that the material gets nipped.

In order to get the best results, material should be fed centrally into the valley formed by rolls, uniformaly, continuously throughout the width of rolls, at a velocity very near to surface velocity of rolls. One roll is fixed and other roll is floating spring loaded or hydraulically loaded to kick-back in the case of overload or uncrushable coming into crushing zone and same roll can be moved closer or away to get the desired gap. See gap setting arrangement. Rolls are made of Mn (14%) steel or K.M.D. Steel.

Advantages of Smooth Double Roll Crusher :

1. As the material is crushed only once, when it passes through the gap, the percentages of fines is much less.
2. As there is no to & fro movement, but a fixed gap, percentage of oversize is bare minimum, that too, only in two dimensions & one dimension is always less than gap setting.
3. By setting the gap to say 80% of the product size, 100% desired product, without oversize can be achieved.
4. With the given capacity & reduction ratio, smooth double roll crusher is the most economical crusher.
5. Maintenance very simple & capacity-wise it can be compared to cone crusher.