RETSCH offers the largest selection of laboratory ball mills in the market! Ball mills are among the most variable and effective tools when it comes to size reduction of hard, brittle or fibrous materials. The variety of grinding modes, usable volumes and available grinding tool materials make ball mills the perfect match for a vast range of applications.
- Sample volumes up to 6 x 20 ml
- Final fineness*: 0.1 µm
- Cell disruption via bead beating
- Grinding by impact and friction
- Sample volumes up to 4 x 220 ml
- Final fineness*: 0.1 µm
- Extremely high centrifugal forces result in high energy input
- Dry and wet grinding by impact and friction
- Sample volumes up to 2 x 45 ml
- Final fineness*: 0.08 µm
- Easy, ergonomic handling
- Three different types of mills (ball movement)
- Sample volume up to 35 l
- Final fineness*: < 15 µm
- Large feed sizes*: <20 mm
- FoodGrade version of 316L steel available
- Sample preparation for subsequent X-ray diffraction (XRD)
One ball mill is not like the other
What makes one ball mill better suited for a specific purpose than another? To understand the factors that differentiate ball mill types, we will first look at their common characteristics. Basically, the working principle of each ball mill is the same: it is based on the concept that the sample material is moved potentially together with grinding balls inside a closed jar. This movement results in strong mixing and crushing effects of the material. The apparent difference, which can be seen immediately, lies in the different way the jars move. The classification of ball mills according to their movement is typically reflected in their names. In a planetary ball mill, for example, a jar rotates on a circular path similar like a planet rotates around the sun, in a mixer mill a jar performs an oscillating shaking movement in a horizontal position and in a drum mill the jar simply rotates around its central axis, see Figure 1.
Ball mills are furthermore characterized by significant differences in the sizes of available grinding jars. Retsch offers mills with jar capacities from 1.5 ml up to 150 l and balls are available from 0.1 mm to 40 mm, see Figure 2.
A third and very important characteristic of a ball mill, which also has a great influence on the result of a milling process, is the power of a mill. Depending on the application, jars should be moved either slowly for gentle material processing or, most commonly, at high speed for effective grinding effects. Here, the maximum speed, which is given as maximum frequency or maximum revolutions per minute (rpm), is often used as a synonym for performance. A more meaningful physical quantity than speed is the acceleration force "g", which is induced by the kinetic energy of a ball mill. In the High-Energy Ball Mill Emax for example, an unrivalled acceleration of 76 g can be obtained, if running at its maximum speed of 2000 rpm.
- 2 mL metal cups
- 500 mL EasyFit jar
- Grinding balls of various sizes
Selecting the most suitable ball mill
To identify the most suitable ball mill for a particular application, the task and required outcome need to be defined. Sample size, batch volume, process time, available materials of grinding tools and final fineness are the keywords here. Once the application requirements are clear, a suitable mill can be selected. To facilitate this process, Retsch displays the strength and efficiency of each ball mill model in a spider-net diagram, see Figure 3.
A planetary ball mill, for example, offers a big jar volume compared to a mixer mill and shows a high value on this diagonal. A mixer mill in contrast offers various possibilities for temperature control and has a high value in this field. Considering that a single ball mill is most often used for a variety of applications, a good compromise must be found to ensure that all application requirements can be optimally met.
Figure 3
Dr. Lena Weigold explains how to select the most suitable ball mill
This compact guide outlines three essential rules for achieving optimum ball mill set-up and guides you through the selection of accessories and process parameters to achieve the best results every time.
