NUTRITION
PIH-94
pork
industry handbook
COOPERATIVE EXTENSION SERVICE • PURDUE UNIVERSITY • WEST LAFAYETTE, INDIANA
Calibrating Meter-Type Feed Mills
Authors:
E. Dale Purkhiser, Michigan State University
Peter D. Bloome, Oklahoma State University
Reviewers:
Curtis Bailey, Schoolcraft, Michigan
Bruce McKenzie, Purdue University
Bob Renbarger, El Reno, Oklahoma
Art Singleton, Logansport, Indiana
Robert Wilcox, Kansas State University
Meter-type feed mills (sometimes called automatic electric mills) are feed processing units which meter ingredients separately and blend them together in controlled flow rates. Blending takes place while the grain is ground and/or during conveying of the ration. Finer ingredients may bypass the grinding chamber. Each ingredient is supplied by a separate metering device.

Different brands of mills feature different types and locations of metering devices (Figs. 1 and 2). Meter types include:
•	variable speed proportioning augers,
•	adjustable gravity flowspouts above belts or rotating tables,
•	fluted wheels with adjustable flow gates,
•	vibrators with adjustable flow gates.

Ingredient meters measure material by volume while ration formulations are specified by weight. Calibration is the process of determining the meter settings that will produce the desired ratio of ingredient weights in the ration. Periodic calibration checks are used to determine if the original meter settings are still producing the desired ratio of ingredient weights.

This fact sheet is intended as a guide for calibrating meter-type feed mills. It also includes a discussion of factors affecting ration quality control.

Preparing for Calibration
Read the calibration section of the owner's manual. The manual describes the recommended calibration procedure for your mill and may contain charts and
tables as calibration aids. Some manufacturers also offer optional equipment, such as counters attached to ingredient meters, sampling chute assemblies and/or specially shaped sample containers for use in calibration.

A data sheet should be prepared for each ration before going to the feed center. An example of a Calibration Data Sheet is shown in Table 2, accompanied by an explanation of how the sheet is completed. The ratio of ingredients in the ration is calculated and recorded. The completed data sheet shows the date, times used in calibration, meter settings, and weights of ingredients delivered during the recorded time periods. The completed data sheet should be kept in the feed center for reference during calibration checks. Keeping a copy of the data sheet in your office is a good practice.

Calibration requires a container or set of containers to collect ingredients for weighing and an accurate scales. The timed method of calibration also requires a stop watch or a watch with a sweep second hand. A hand-held calculator will assist in making rapid calculations.

The Timed (Sequential) Method
The timed method of calibration, illustrated in Figure 3, can be applied to all meter-type mills. It is the easiest, most readily understood method. The flow rate of each ingredient is determined by weighing the amount of ingredient collected during a certain timed period. The flow rates (meter settings) of the individual in-
Cooperative Extension Work in Agriculture and Home Economics, State of Indiana, Purdue University and U. S. Department of Agriculture Cooperating. H. A. Wadsworth, Director, West Lafayette, IN. Issued in furtherance of the Acts of May 8 and June 30, 1914. We adhere to the policy that all persons shall have equal opportunity and access to our programs and facilities.
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