Why rice mill yield never matches paddy intake and how to find the gap

Paddy is a weight you buy and a weight you cannot fully sell. Husk leaves first. Bran leaves next. Water follows. Water leaves during drying and storage, and a lot held for several weeks in a warm bay keeps losing a little more of it each day. Hulled rice, called brown rice, loses weight again when the bran layer is polished off, and a parboiled lot behaves differently from a raw one in both cases.

Whole milled rice, called head rice, is only one output. Broken grain, brokens of smaller size, bran and husk make the rest. Each sells at its own price to its own buyer.

Split the gap into expected shrink and unexplained loss. Only the unexplained part deserves a hunt.

A truck of wet paddy weighs more and yields less. If the moisture reading is rough, or written on a slip that gets lost, the lot starts with a wrong baseline. Wet paddy dried in a recirculating dryer can lose several points of moisture in one pass. Ticket weight and bin weight will never match.

Take samples from the top, middle and bottom of the truck. Use one meter, calibrated on a schedule. Record the reading against the lot, since a supplier’s name alone cannot show which load was damp.

Drying changes weight again. A lot that enters at one moisture reading and leaves the dryer at another has lost water, not rice. Record both weights.

Many mills draw from several bays into one hopper. That is normal. The trouble starts when no one records the ratio.

A poor milling outcome then cannot be tied to a variety, a supplier or a harvest. The records say only that the mill ran paddy. You are left guessing. Mixing a long-grain lot with a short-grain lot also shifts the broken share, because the two varieties break at different rates in the huller and in the whitener.

Ask the line supervisor to log every hopper draw by lot and quantity. Even a plain sheet clipped beside the hopper, filled at every change of bay, gives you a record that memory never will.

At the end of a run, weigh head rice, broken grain, bran and husk separately. Add the total and compare it with the paddy that went in. What remains unexplained is the true variance.

Sort the outputs by grade, since a high broken share lowers the value of a run even when total weight looks fine. Polisher and sorter settings influence this, so note them too. Rice that is graded through an indented cylinder and a colour sorter drops rejects at each step, and those rejects need a destination, whether re-milling, feed or sale.

Husk and bran often leave the plant without a weighbridge entry. Those sales drop out of the yield sums, and the mill appears to lose weight it simply sold.

Build a standard yield for each variety and moisture band from your own past runs. Every new run is then compared with that standard, and not with the mood of last week’s shift. Even forty runs of data give a usable baseline for each variety, provided the moisture, the polisher setting and the lot are recorded with every run.

Sort variances by lot, by shift and by machine. A pattern usually appears within a month. One shift might run a roller too hard, or one supplier may deliver damp, immature grain.

Software does this sorting without effort, but the sheet works first. Log the lot at the hopper tomorrow.