In the industrial mixing and processing world, kneaders are essential machines used for handling high-viscosity materials such as rubber, silicone, sealants, adhesives, polymers, plastic ,color master batch, ceramic powder, chemicals and even pharmaceuticals etc. These high-viscosity materials are very stick and thic, not easy to flow ,thus them require powerful mixing equipment that ensures uniform blending without compromising quality.
There are various mixing machine , among them, lab kneaders and sigma kneaders are commonly used .
Although the two terms are often used interchangeably and confused by many people, yet their size, design,scale , and application are different ,which make them suitable for different purposes.
In this blog, let us explain the difference between lab kneader and sigma mixer as follows:
1. What Is a Sigma Kneader?
A sigma kneader is an heavy-duty industrial mixer designed to handle large batches of highly viscous or elastic materials . The sigma mixer machine is equipped with a pair of sigma-shaped blades mounted on parallel shafts. These two counter blades rotate toward each other at different speeds, creating intensive shearing, squeezing, and folding forces to mix high-viscosity or highly elastic materials efficiently.
Key Features of Sigma Kneaders:
* Heavy-duty structure designed for large-scale industrial production.
* Equipped with sigma-shaped blades for intensive mixing.
* Suitable for highly viscous materials like rubber compounds, silicone sealants, ceramic powder and other polymer adhesives.
* Can be featured with jackets for heating/cooling and vacuum systems.
* Capacity ranges from 5 liters up to several thousand liters.
How Does Sigma Mixer Works
When the sigma kneader mixer begin working , its two sigma-shaped blades inside a sealed mixing chamber rotate toward each other at different speeds. Its rotating direction is opposite .
Through this rotating action , it create an intensive force of shearing, folding, and stretching to the compound material, which makes it suitable for high-viscosity compounds such as:
The compound material is mixed and blended ,they are compressed, stretched, and homogenized with other agents, additives or fillers like fumed silica, pigments, thoroughly and uniformly.
Usually ,the sigma kneader mixer can be equipped with jackets system for heating/cooling control ,so that maintain process temperature,which is critical for thermal sensitive material.
The sigma mixer for adhesive can also be optically equipped with vacuum systems
to remove air bubbles and degas .
Applications of Sigma Mixer :
Rubber compounds, Silicone elastomers , adhesives, sealants & mastics, resins, plastics, polymers ,battery materials, food pastes, pharmaceuticals, etc.
2. What Is a Lab Kneader?
A lab kneader machine is essentially a smaller version of a sigma kneader, it is a laboratory-scale machine designed for research, testing, and small-batch production , specially used for mixing, kneading and stirring high-viscosity and elastoplastic materials, such as rubber, plastics, adhesives , PVC , color master batch, ceramic and pharmaceuticals etc The lab kneader also adopt sigma blade for sample or lab formulation testing usage, thus it require at lower capacity but not mass production usage.
Key Features of Lab Kneaders:
* Uses sigma blades—Some also use sigma mixer as industrial sigma kneaders.
* Compact size, typically ranging from 0.5 liters to 5 liters.
* Suitable for R&D labs and formulation testing.
* Easier to clean and change materials frequently.
* Can simulate industrial mixing processes on a small scale.
How Lab Kneader Works
Similarly , the mixing chamber and sigma blades inside lab kneader is exactly the same as function of industrial sigma kneader.
But the difference of these two equipment lie in the size, automation, and usage.
Small Lab kneaders machine are easy to clean, operate, and frequent to change materials each batch. The laboratory kneader are usually work on material testing or formulation for industrial-scale mixing.
Applications of Lab Kneader
The laboratory kneader is mainly used to mix , knead and stir for high-viscosity, high-elastic-plastic materials, commonly used for R&D labs , quality control testing, sample production, formulation and pilot-scale material development.
3. Are Lab Kneaders and Sigma Kneaders the Same?
Yes and No.
✓ Yes, because lab kneader is actually one kind of sigma kneader technically ,both of them adopt the same sigma-shaped blades and working principle is nearly the same .
X No, The main difference lies in capacity ,control precision and application scope .
Here ,we can compare the difference between Sigma Mixer and Lab Kneader as follows:
| Aspect | Lab Kneader | Sigma Kneader |
| Working Principle | Sigma blade mixing | Sigma blade mixing |
| Capacity | 0.5 L ~ 5 L | 5 L ~ 3000+ L |
| Purpose | R&D, formulation testing, small batch | Industrial-scale mass production |
| Precision | High- suitable for testing material properties | Moderate -focuses on high output |
| Control System | Often PLC-controlled with fine temperature and torque control | PLC system equipped optical |
| Design | Compact, portable, easy to clean | Heavy-duty, larger footprint |
| Applications | Testing new materials or formulation | Industrial produc bulk order |
| Flexibility | High, frequent material changes possible | Lower, designed for one material per batch |
| Output Volume | Small batches for quality testing or formulation | High-volume continuous production |
| Cost | Lower | Higher |
| Appllication | Adhesives, silicone,rubber,sealants,polymers | Same material,but at industrial scale |
4. How to Choose Between a Lab Kneader and a Sigma Kneader
So how shall we select and chose the most suitable mixing machine for your lab or manufacture ? Before you make choice ,you need to consider several question as follows:
1. Production Scale — If you just need one testing equipment for your R&D setting or new formulation for small batches , then a lab kneader equipment is ideal for you because it is compact size and also economic . But if you need to buy one industrial mixing machine for high-viscosities material for large-scale manufacturing, then you need to choose an industrial sigma kneader, though it is more expensive .
2. Testing Material or Formulation — If your material need to swith frequently for different texting , then compact ,flexible but very pratical lab kneader is your good choice because it is easier to operate and clean. But industrial sigma mixer is much more hard to clean after each mixing .
3. Budget — Because small and flexible Lab kneaders are more compact , thus it is cost-effective for small lab setting, while industrial sigma kneaders are much more huge , it need higher investment and more space to install the machine.
4. Scaling Up— Many manufacturers start with a lab kneader to test material sample or find best formulations for mass production, or then move to industrial sigma kneaders machine for full-scale production.
In essence, a lab kneader equipment is a smaller, R&D-focused version of a sigma kneader.
Although both machine share the same mixing principle and sigma blade design — the sigma blade mixing mechanism — yet they differ significantly in size, capacity and applications:
* Lab kneader = small-scale, flexible, R&D-focused
* Sigma kneader = large-scale, industrial production
If your manufacture want to develop new formulations or materials testing in lab R&D setting , a lab kneader equipment suit your needs. But if are producing high-viscosity materials ,like rubber, silicone, sealants, adhesives, polymers, and chemicals etc for large-scale manufacturing, an industrial sigma kneader machine is the better solution.
At Simptek , we can design and manufacture both of these two mixing machine tailored to your needs.