Sicoma Strength    TWIN SHAFT MIXERS

The Sicoma twin shaft concrete mixer was designed in Italy 20 years ago;  it has been refined to give you the outstanding product that you see today. The MAO series heavy duty mixers are the most widely used twin shaft models in the world today;  over 6000 in use, worldwide,  in ready-mix, precast, block, paver and dam applications.  These mixers produce well over 1 million cubic yards of concrete every day. Their compact size allows them to be retrofitted into existing plants, in most cases doubling throughput without the need for two mixers and splitting of material feeds.

The art in concrete mixing is to make a batch of concrete quickly and completely. The MAO's powerful compulsory spiral mixing action throws particles from each side of the mixer towards the center, where they combine; the water is forced through powerful jets into the mix, where it is absorbed completely, allowing the cement slurry to coat all the aggregate particles uniformly, forming the strongest concrete.

Because the mixing occurs in free space above the mixer floor, the wear on the liner plates is very low; the outer 70% of the lined surface is rarely touched by concrete. Only the rows of tiles close to the discharge door will need replacement and you’ll be surprised at how long they last.

The MAO’s features go farther than any other mixer of its class. Its strong frame, triple shaft seals, harder liner plates, more efficient gear reducers and electronic alarm unit as standard equipment mean that you have peace of mind. And our 5 year warranty shows you that we are very confident in its reliability!   
Frequently Asked Questions on Sicoma twin shaft mixers

The heavy duty twin-shaft mixer design gives 70-second cycle times, low wear of liner and very efficient mixing, allowing greater throughput and stronger concrete.

  Download printable brochure (1.6M)    Download dimension sheet (312K)    

TRIPLE SHAFT SEALS

Sicoma's shaft seals are more effective and long lasting than any other.  While other seals pump grease through a "labyrinth" into the mixer to counteract the pressure of the concrete entering the seal, Sicoma's shaft seal acts as a one-way valve.  The pressure of the concrete, due to its level being above the shaft, actually closes the flexible seal against the shaft.  The internal cavity is filled with grease but very little escapes through the seal;  its function is only to lubricate the moving surfaces.  As a result, no contamination of the mix occurs and usage of grease is a mere 650 grams per day - 1/20th of other leading models. This major feature is internationally patented and is only found on Sicoma mixers. 

If the seal should ever fail, separation of the bearing from the seal positively prevents contamination of the bearing.

More on seals

EXTRA FRAME STIFFENERS

Special box sections unique to the MAO's extra-rigid design hold mixer shape and maintain shaft alignment during heavy mixing periods.  Compare with lighter designs;  the MAO's resistance to twisting preserves the full life of seals and bearings, making it one of the most reliable mixers in the world today.

EXTRA-HARD LINER PLATES

Brinell 600 Ni-hard tiles give  longer life with extra-abrasive aggregates, compared with others.  All tiles are identical and all mixers use the same size, reducing stock and simplifying installation.  Note that offset joint/rhombic tiles have been discontinued, since no advantage has been found in practice.   Wear comparison for different materials.

MIXING ARMS

Cast from spheroidal cast iron with extra wide and strong but streamlined design to minimize buildup, they are set at 90° angles to give fastest mixing while minimizing stress of the shafts. Paddles are Brinell 600 Ni-hard cast iron with greater area and thickness than most others. Collars between arms prevent material buildup on shaft and act as spacers during assembly. 

GEAR REDUCER AND BEARINGS

The MAO's high-efficiency 2-stage design does not require a cooler, even for 24 hour 7 days a week continuous duty. Gearboxes and all bearings are oil-bath lubricated, eliminating the need for frequent greasing and its attendant maintenance hazard.

In all the mixers produced over the last 40 years, not a single gearbox has required replacement.  All gearboxes are guaranteed for 5 years/10,000 hours of use.

More facts about gearbox efficiency and heating.

ONE-DAY SHAFT REPLACEMENT

Unlike others that require several days to remove and replace power train components, the MAO can be stripped down and rebuilt in hours. If you ever have to replace a shaft,  bearing or shaft seal, you are done in a day – not a week!

MOTOR DRIVE

V-belt drive absorbs shock loads whilst a very strong positive coupling between the two drives synchronizes the shafts, making it virtually impossible for the two shafts to get "out of sync".  Gearboxes are coupled to the shafts through flexible joints to eliminate misalignment and wear under heavy loads

Models up to MAO 7500 have two motors.  MAO9000 and MAO12000 “Janus” have four motors, balancing the torques in the shafts and creating an extremely rugged design.

ELECTRIC GREASE PUMP

Constant lubrication of shaft seals ensure trouble free life.  The grease from the pump is sequenced to each seal in turn;  if any path is blocked, a sensor sends a signal to the alarm unit.  The seal is so effective, however, that it can operate for extended periods with no damage or contamination.   Discharge door and actuator pivots are lubricated manually from a single location.

Optional Grease Refill Cart:  allows the grease reservoir to be refilled without any danger of contamination and makes it an easy job.  Download brochure.

HYDRAULIC POWER UNIT

The discharge door is operated hydraulically by the built-in power unit. A manual lever allows the door to be opened if power is lost.

MIXER COVER AND WATER DISTRIBUTION

Included in the standard mixer price, the cover has built-in water pipes and jets designed to give high-speed water addition with optimum distribution, giving the fastest mixing time.  Black pipes shown are for washout system - see below.

GULL-WING ACCESS HATCHES

The standard cover includes two gull-wing hatches for wide access, located on either the front, back or both sides.  Inspection ports are also included, built into all hatches.  High-security locking cover latch  disables startup, ensuring safety even if separate lockout switch is overlooked.

Optionally, lights can be fitted in the cover for better viewing.

DISCHARGE DOOR

Hydraulically operated, the door has 3 adjustable stopping positions to regulate the flow when necessary. The door is eccentrically mounted on the pivot shafts, allowing the door to draw away from the seals as it opens.  This reduces wear and the possibility of jamming, making it maintenance-free for many years.  Wear of the double rubber closing seal is automatically compensated by the closing cylinder;  closing is by pressure, not position.  The result is a tight sealing, fully waterproof door. It is easily removed for maintenance.

A new proximity sensor arrangement is extremely rugged and easy to adjust.  Together with a pressure cutoff switch on the hydraulic pump, the control system can detect the difference between proper closure and incomplete closure;  a simple but important feature that costs nothing but eliminates problems.

Learn about the Reduced Discharge Door and other discharge options.

INSPECTION PLATFORM

All mixers come with the inspection platform as standard.  This platform is modular, easy to assemble.  Its strong construction allows personnel to safely inspect mixing action and verify slump etc.  It is also used for access to clean and maintain the mixer interior.

Optional second platform and stairs are also available.

HIGH PRESSURE WASHOUT

The optional high-pressure pump, together with a separate motor driven rotating shaft with spray nozzle system , forces water at 900 psi and 50 gallons per minute into every corner of the mixer while it rotates, cleaning it in minutes.  A high pressure wand is also provided for catching the more inaccessible areas.  Alternatively, to almost eliminate the need for end-of-day cleanout, the system can be used as an inter-batch rinse, the waste water being used in the following batch.

BATCHING CONTROLS

Scale-Tron’s BATCHTRON series controllers take advantage of the MAO's high mixing speed to give you more throughput per hour. Easy to operate and set up, MAO’s mixing sequence can be programmed in different ways for different formulas.

LOAD CELL MOUNTING HOLES

Entire mixer can be weighed for checking batch weight and verifying complete discharge. Contact plant for details.

ALARM UNIT

Standard on all models, alarm unit indicates faulty grease supply to seals, low levels of lubricants and hydraulic fluid plus overtemperature in gearboxes and hydraulic pump. Faults are indicated by an alarm light which connects to the control system for automatic shut-down.

5 YEAR WARRANTY

The MAO is the only mixer with a 5 year / 10,000 hour gearbox warranty.  Other parts that fail during this period will be examined on a case-by-case basis and will be replaced free of charge if subject to manufacturing defects. This shows you how confident we are in the MAO mixer’s reliability.

MIXING ACTION

The counter-rotating blades are angled at 45° to throw the mix towards the opposite side of the mixer while imparting an axial motion at the same time. MAO has one more set of blades on each shaft compared with others of the same size, perfecting the spiral mixing action that forces the mix to circulate in a counterclockwise direction, allowing the ISO target of 95% homogeneity to be reached within 30 seconds and a 98.5% homogeneity in 60 seconds.  The result is a faster and better mixed batch than with any other twin shaft mixer, both for regular slump concrete and SCC.

Discharge is complete in an incredible 10 seconds, giving a total mixing cycle time of typically 70 seconds for wet cast and a little longer for zero slump mix.  Ready-mix can be produced even faster if sand, cement and water are pre-mixed while stone is blended through the mixer during discharge, with final mix being completed in transit. The result is better quality and higher strength concrete than with transit mixing alone.  It also prolongs the life of the mixer drum, giving major savings in fleet maintenance that far outweighs the initial expense of the mixer.

There are no dead zones within the mixer; the vigorous motion of the mix ensures that material in the unswept area above the door is moving at all times while eliminating segregation when using lightweight and other special aggregates and SCC mixes.

REDUCED AND DOUBLE DISCHARGE DOORS

Two new major features only found on Sicoma twin shaft mixers, the Reduced and Double discharge doors give these mixers much of the flexibility of the planetary and turbine mixers.  More information

MOISTURE CONTROL

Most models of microwave moisture sensor can be mounted in the end structure or floor.  Scale-Tron’s microwave moisture systems give you ultimate control of moisture for both wet and dry cast concrete.

THE WIDEST SELLING MIXER IN THE WORLD

Over 1200 MAO mixers are currently sold annually, worldwide.  Over 6000 are in use, showing that the MAO is chosen again and again by people that know their mixers. 

It's simply the world's best choice.

  Application in ready-mix:  Burj Dubai, world's tallest building
 

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The MAO is simply the world's best twin-shaft mixer;  be sure to check it out.

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 a batch of wet cast or ready-mix concrete can be produced in less than 90 seconds, with dry cast, block and paver mixes taking a little longer.  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.

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