A Sigma Mixer Extruder (also known as a Kneader Extruder or Sigma Blade Mixer with Extruder) is a specialized industrial mixing machine designed for processing highly viscous, sticky, or dough-like materials. It combines the intensive kneading action of a traditional sigma blade mixer with an integrated extrusion screw for efficient discharging of the mixed product.
Extruder Sigma Mixer Video
Key Components and How It Works
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Mixing Chamber: Typically a U- or W-shaped trough that holds the material.
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Sigma Blades: Two Z-shaped or sigma-shaped blades mounted on a horizontal axis. They rotate in opposite directions (counter-rotating) at different speeds, creating a shearing, folding, stretching, and smearing action to ensure thorough mixing.
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Extrusion Screw: Located in a separate cavity below the blades. During mixing, the screw rotates in reverse to feed fresh material upward into the blades, intensifying the kneading process and preventing settling. After mixing, the screw reverses direction to extrude the finished product through a discharge die at the bottom or side.
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Additional Features (common in models):
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Jacket for heating/cooling (e.g., steam, hot oil, or water circulation) to control temperature.
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Hydraulic tilting mechanism for complete emptying in larger models.
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Vacuum capability for de-aeration or solvent recovery.
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Variable speed drives and explosion-proof motors for safety in volatile environments.
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The process is efficient for batch operations: materials are loaded into the trough, kneaded for a set time, and then extruded directly onto downstream equipment like conveyors or packaging lines.
Common Applications
Sigma Mixer Extruders are widely used across industries for handling tough-to-mix substances:
Food: Dough, bubble gum, chocolate pastes, fondants
Pharmaceutical: Ointments, gels, pastes, suppositories
Chemical: Adhesives, sealants, inks, putties
Rubber/Plastics: Rubber compounds, silicone, polymers, hot melts
Cosmetics: Creams, lotions, thick emulsions
Specifications and Variations
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Capacity: Ranges from lab-scale (5–50 liters) to production-scale (up to 5,000–10,000 liters).
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Materials: Typically stainless steel (e.g., SS304/316) for food/pharma grades; carbon steel for heavy-duty industrial use.
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Power: Varies by size; e.g., 5–10 HP for small models, up to 100+ HP for large ones.
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Discharge Options: Screw extrusion (standard), tilting bowl, or bottom plate.
Salient Features of Sigma Mixer Machine
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Available in Stainless Steel 316, Stainless Steel 304 and Mild Steel materials.
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Stainless Steel polish to matt & mirror finish as per customer’s requirements.
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Mild Steel finish with one coat of red oxide and two coats of epoxy paint.
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Discharge option of hand wheel operated (manual) or hydraulic operated (automatic) offered.
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Jacket for heating or cooling application can be offered.
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Mineral wool insulation with cladding on jacket.
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Tangential designed ‘Z’ blades offered for uniform mixing.
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PTFE made shaft sealing provided for food grade compatibility.
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Minimum gap between trough inner shell & blades removes possibility of sticking product.
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On demand Spray system, vacuum system
Optional Features/Accessories of Sigma Mixer
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Liquid Spray System
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Vacuum System
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Blades Cooling Arrangement
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Screw System
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Automatic Valve Discharge System
Process Operation of Extruder Sigma Mixer
In Sigma mixer tangential action of mixing and kneading obtained by ‘Z’ type (SIGMA) shaped kneading blades, which rotates very accurately at different speed towards each other causing product to be transferred from one end to another end. Discharge of the finished product is achieved by tilting the container or through the valves at the bottom or by means of an extrusion screw beside the container.
The mixing action is a combination of bulk movement, stretching, folding, dividing, and recombining of the material. The shearing & tearing action of the material against blades and the side walls causes size reduction of the solids. After the time period required for sterilizing the batch has elapsed, the heating circuit shuts of the pneumatics damper (exhaust) opens and cooling operation commences.
In the tangential design, the blades rotate in the trough meeting tangentially. The front blade generally rotates faster than the rear blade usually in the ratio of 3:2. Tangential blades are generally used for material of higher viscosities such as adhesives, rubber compounds, flush colors, dyes, and pigments.
In the overlapping design, the blades overlap above the saddle of the container. Due to the overlapping action, it is necessary that the relative position of the two blades is unchanged, and as a result, both the blades rotate at the same speed. Materials that flow freely or creep down into the blades are mixed using the overlapping blade action. This design offers a faster interchange of material from one blade compartment of the mixer to the other. Overlapping blade action is used for materials of lighter viscosities such as carbon pastes, clay coating, creams, and ointments. The overlapping blade produces a lower kneading and shearing compared to the tangential blade action.
Technical Specification of Sigma Mixer Kneader
| Model | Capacity – Liters | Motor (H.P.) | ||
| Working Capacity approx. | Gross Capacity approx. | General | Heavy Duty | |
| ASM – 50 | 50 Liters | 80 Liters | 5 H.P. | 7.5 H.P. |
| ASM – 75 | 75 Liters | 110 Liters | 7.5 H.P. | 10 H.P. |
| ASM – 100 | 100 Liters | 150 Liters | 10 H.P. | 15 H.P. |
| ASM – 150 | 150 Liters | 200 Liters | 15 H.P. | 20 H.P. |
| ASM – 200 | 200 Liters | 300 Liters | 20 H.P. | 25 H.P. |
| ASM – 400 | 400 Liters | 550 Liters | 30 H.P. | 40 H.P. |
| ASM – 500 | 500 Liters | 750 Liters | 40 H.P. | 50 H.P. |
| ASM – 750 | 750 Liters | 1150 Liters | 50 H.P. | 60 H.P. |
| ASM – 1000 | 1000 Liters | 1500 Liters | 60 H.P. | 70 H.P. |
| ASM – 1500 | 1500 Liters | 2100 Liters | 75 H.P. | 80 H.P. |
| ASM – 2000 | 2000 Liters | 2600 Liters | 80 H.P. | 90 H.P. |
| ASM – 3000 | 3000 Liters | 3800 Liters | 100 H.P. | 120 H.P. |
* Power voltage can be adjusted as per customer’s domestic power voltage requirements.
* Rights of technical improvements & modification reserved.
* Illustrations & dimensions are shown for information purpose only.
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