Sigma Mixer
The Sigma Mixer, also widely known as a Sigma Blade Mixer or a Double Arm Kneader, is a
heavy-duty industrial mixing machine specifically designed for the continuous and thorough
blending of highly viscous materials. Its construction features a stationary trough, which is typically
U-shaped or “W”-shaped, and houses two heavy-duty mixing elements shaped like the Greek letter
sigma (Σ). These blades are mounted horizontally and operate within the trough at a very close
clearance to the walls and to each other, which is crucial for generating the high shear forces
necessary to process stiff, plastic, or rubbery masses.
The core working principle relies on a combination of intensive shearing, stretching, folding,
dividing, and recombining the viscous mass. The two sigma blades rotate toward each other,
generally at differential speeds—most commonly in a ratio of 3:2. This speed difference prevents
any material from clinging to a single spot and creates a powerful, tangential kneading action. One
blade, rotating faster, pulls the material from the trough wall and forces it across a central ridge, or
“saddle,” where it is then met by the slower-moving blade, which folds and pushes the material
back.
This powerful, counter-rotating motion subjects the material to a high-pressure tensile and shearing
stress, simulating the action of manual kneading. The blades’ geometry is expertly designed to
ensure a constant turnover of the batch, pulling the mass, tearing it apart, and compressing it against
the container walls and the saddle. This mechanical process efficiently breaks down any large
particles, lumps, or agglomerates present in the mixture, rapidly creating new surfaces and ensuring
that all components, including minor additives, are thoroughly and uniformly dispersed.
Features:
Designed for highly viscous & sticky materials
Powerful kneading and shearing action
Twin sigma blades with differential speed
Handles pastes, doughs & rubbery masses
Breaks lumps for uniform dispersion
Heavy-duty construction for continuous use
FAQs
A Sigma Mixer is used for mixing and kneading highly viscous, sticky, and plastic materials.
Sigma blades create strong shearing, folding, and kneading action required for thick and dense materials.
The two blades rotate at different speeds (commonly 3:2) to prevent material stagnation and ensure uniform mixing.
It is ideal for dough, adhesives, rubber compounds, sealants, pastes, and viscous chemical formulations.
Pharmaceutical, food, chemical, rubber, cosmetic, and polymer industries widely use Sigma Mixers.