BOLA Comfort search
Search in products
Search in products
 
Article number
Article number
 

Basket: Empty

Technical information

What you should know about magnetic stirring and mixing

For optimum results, both drive magnet and stirring bar are decisive. For optimum efficiency, the distance between the magnetic poles of the drive magnet and the length of the stirring bar should be equal. A magnetic stirring bar which is too small will eventually gravitate toward one of the poles of the drive magnet. Stirring efficiency is influenced by the material, by the thickness of the cover plate and the thickness of the vessel. For the best magnetic coupling, the distance between the magnets should be minimized.

What you should know about the choice of stirring bars

Improperly selected stirring bars are often cause flickering of the bars in the vessel, respectively ineffective mixing of the product.
You can find an overview of the most common stirring bars here below:

Cylindrical Magnetic Stirring Bars:

They are the most commonly used magnetic stirring bars. Due to their simple shape they can be offered at very attractive prices. Cylindrical magnetic stirring bars offer excellent centering and smooth running characteristics.

Ultra Magnetic Stirring Bars:

These magnetic stirring bars have very smooth and seamless surfaces. No substance can penetrate into their surfaces and thus, all following processes are not affected by any „carry-over“. They are mainly used for high-purity work or trace analysis.

Power Magnetic Stirring Bars:

Due to special magnetic material, their torque loads are larger than those of conventional magnetic stirring bars. Power magnetic stirring bars are mainly used for agitating viscous liquids or for bridging larger distances between the magnetic stirring machine and the magnetic stirring bar.

Magnetic Stirring Bars with Pivot Ring:

Their interrupted surface provides greater surface area and added turbulence. Only their pivot ring and one end of the magnetic stirring bar touch the bottom of the vessel. Therefore these magnetic stirring bars have a more steady spinning position and a better longevity.

Square Magnetic Stirring Bars:

They are particularly suitable for big vessels due to the high magnetic force. Solids are released or removed from the bottom of the vessel.

Egg-Shaped Magnetic Stirring Bars:

They are particularly suitable for round-bottom flasks. Their shape mimics that of the flasks and assures complete mixing. Those magnetic stirring bars have an egg-shaped magnetic core which assures a better force transmission than a cylindrical core.

Triangular Magnetic Stirring Bars:

Such magnets are useful for mixing reagents which resist dissolving or for avoiding any residues at the bottom of the vessels. They provide strong turbulence at relatively low speeds.

Glass Magnetic Stirring Bars:

They have a non-porous and smooth glass-coating. All following processes are not affected by any carry-over. There is an increased abrasion between glass vessels and glass stirring bars.

Star Head Magnetic Stirring Bars:

Optimum stirring in tall, narrow diameter vessels. Ideal stirring bar for cuvettes or test tubes.

Center Magnetic Stirring Bars:

These magnetic stirring bars provide better stirring action and a more stable spinning position due to the punctual position.

Tolerances of the magnetic stirring bars

The dimensions of the magnetic stirring bars are nominal dimensions which can have a tolerance of +/- 5% in length and +/- 10% in diameter.

We “meliorate” your specific magnetic stirring bars

  • These stirring bars can for example be built in devices or can be used for special applications
  • The diameter of the magnetic stirring bars can be machined with a tolerance of up to +/- 0,02 mm
  • The magnetic stirring bars are ground to obtain a seamless amplitude
  • The ends are polished to receive a round or any other shape
  • The surface is becoming extremely smooth and even, so that contaminations cannot adhere
  • Reproducibility both in diameter and surface are granted