Morehouse Cowles | Selecting Small Media

The selection of the proper media is essential to getting predictable quality results from your milling and dispersion operations. We offer guidelines for Large and Small media selection, but we strongly suggest that you try out our survey form. This will allow you to get personalized service from one of our specialists regarding your specific needs.

Rules for selecting small media

Rule 1: The action of the media must not be impaired by the product viscosity or density.

Rule 2: The media must not destroy the product value through color change, abrasive contamination or chemical reaction.

Rule 3: The media should promote the highest possible thru-put.

Choose a media type between Ferrous and Non-Ferrous. If Non-Ferrous media can be used in the particular mill of this application, it should be the first choice due to price, availability, selection of sizes and choice of densities.
Choose within the Non-Ferrous group. The selection must meet rules 1, 2 and 3 above.
- The bead should be the smallest possible in order to maximize the number of contact points.
- Lighter specific gravity beads will cause less mill and media wear than dense beads, especially during mill wash cycles employing low-viscosity liquids.
- If mill and media wear are not large problems due to dedicated equipment and few if any mill washes, the higher specific gravity media are very efficient.

If the product requires dispersion to a particle size of 1-4 microns and more than one pass through the media mill is probable, then for best efficiency, at least 2 mills would be required, each with a different size media.

The first pass through the mill should be made with a larger bead to work on the large pre-mix agglomerates. After the first pass through a media mill, the large agglomerates should now be smaller and a smaller bead used in order to increase the contact points.

FACT: A sphere 0.5 the size of the original diameter will have 8 times more beads per unit weight.

SMALL IS DESIRABLE IF RULE 1 IS MET. If two mills cannot be used for products requiring multiple passes, a range of sizes in the same mill maximizes efficiency and sphere count. That is, use a 10-16 mesh size range of media. The 10 mesh size is necessary for the large agglomerates. The 16 mesh works on small agglomerates and increases sphere count.

Media and mill liner compatibility chart

Important: To make sure that your media and your mills liner material are compatible, and to prevent contamination and equipment damage, please use the chart below.

	Mill Liner material
Mill Media	Steel	Rubber	Urethane	Burstone	Porcelain	Hi-density Alumina
Flint
Porcelain
Hi-Density Alumina
Zirconia
Hot-Forged Steel
Cold-Headed Steel
Chrome Steel
Ni-Hard Cast
Hi-Chrome Cast
Stainless Steel

Preferred media

Can be used without
mill damage