Ocmer North America

TWIN SHAFT MIXING CYCLE - to give the fastest mixing times

Although the total cycle time is dependent on the speed at which the charging takes place as well as the type of concrete being produced, typically Ocmix twin shaft mixers can produce a batch of wet cast or ready-mix concrete in less than 90 seconds, with dry-cast, block and paver mixes taking a little longer, although we do not recommend twin shaft mixers for dry-cast concrete due to buildup on the shafts.  Note that some admixtures require extra mixing time.  The diagram below assumes that the aggregates are waiting in a skip or hopper, ready for discharge.  Note the Premix time before water is added;  this is essential to proper mixing and fast mixing times. The short total cycle time allows many plants to be upgraded to give double the output by replacing the mixer only, compared with adding a second mixer, which requires extra conveyors, chutes, holding hoppers and often an increase in elevation of bins and weigh hoppers.

When assessing the cycle time for your own plant, substitute your own plant's times for aggregate, cement and water charging, and longer discharge times if feeding a conveyor or truck.  Note that the next batch is being weighed up as the mixing continues, so that it can charge the mixer as soon as the previous cycle is complete and the discharge door is closed.

Wet cast/slump concrete cycle (typical).  Dry cast not shown - we recommend Planetary for all dry cast applications

 

Charge aggregates 

5s

 

 

 

 

 

 

 Refill

 

 

 

Charge cements

 

15 sec

 

 

 

 

 

 

Refill

 

 

Premix time

 

 

20 sec

 

 

 

 

 

 

Premix

 

Charge water

 

 

 

20 sec

 

 

 

 

 

 

Refill

Charge admixes

Air

 

 

Other

 

 

 

Refill

 

 

etc.

Final mixing time

 

 

 

 

20 sec.  

 

 

 

 

 

 

Discharge time

 

 

 

 

 

8 sec

 

 

 

 

 

Door close

 

 

 

 

 

 

2s

 

 

 

 

Total cycle time

Repeat cycle, beginning to end = 90 seconds