Feed Mill

[Muhammad Ahmad]

Thanks

[Kim Koch]

I agree with ASIA’s post – in the resources tab in the Feed manufacturing discussion board and maybe in the “Feed Milling with …” there is a PPT on size reduction. The suggestion of 10hp/ton is only a generalization – motor size is much more dependent on the design of the hammermill and the number of hammers suspended from the rods – also, most electric motors outside the U.S. run of 50Hz not 60Hz.

[Walid Tawfek Elsherbeny]

Thanks

[Asia Community Manager]

The following is my summary of comments made by Conrado (Don) Bulanhagui during a recent SEC Asia Feed Milling Intermediate Course:

Coarse particles (>1,000 microns) are better for poultry gut health and gizzard development, improving digestion and nutrient absorption. Ironically, coarse particles are more difficult to produce than fine particles. Roller mills are preferred over hammer mills for producing uniform coarse particles in poultry feed primarily because the particle size distribution is typically narrower (less variable) with roller mills than with hammer mills due to the fundamental differences in their grinding mechanisms:

Roller mills use compression and shearing forces where grain is crushed and sheared between two rollers. This controlled and gradual size reduction produces particles that are more uniform in size. By adjusting the gap and speed between rollers, particle size and distribution can be precisely controlled, resulting in a consistent output with less variation.

Hammer mills reduce size by high-speed impact and collision with rapidly moving hammers. This impact action is less controlled and more violent, causing the material to shatter into a wide range of particle sizes—from fine dust to larger fragments—leading to a broader particle size distribution. Hammer mills typically produce more fines and irregular shaped particles compared to roller mills.

Although roller mills can cost about three times more than hammer mills for the same capacity, Don recommended that feed mills with capacities of at least 40 tonnes per hour consider installing a small roller mill (minimum capacity around 5 tonnes per hour) alongside their hammer mill when producing poultry feed. The roller mill not only delivers a more consistent particle size but also consumes only one-third to half the energy of the hammer mill.

He noted that to achieve a particle size of 1,000-1,500 microns for broiler feeds, which stimulates the mechanical activity of the gizzard, leading to its enlargement and enhanced digestive efficiency, the sweet spot with a hammer mill is 700-900rpm, depending on the moisture content of raw materials.

To ensure uniform screen wear and maintain grinding efficiency, Don advised reversing hammer mill screens daily. As a rule of thumb, the minimum motor size for a hammer mill should be 10 horsepower per tonne per hour at 60 Hz.

The pros and cons of hammer mills, relative to roller mills are in the attached Table.

Pros-and-cons-of-hammer-mills-compared-to-roller-mills.docx 18 KB Word Document - Click to view

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[TAIRU AHMED ISHOLA]

thanks very much for the knowledge shared.