Machine Design

Weighing system lets bottles fill fast

Digital load cells with high-speed dynamic weighing capabilities make it possible to fill baby bottles with formula at a rate of 10,000/hr, about three per second.

This soybean oil bottling machine incorporates its own control system and multiple Fast Intelligent Transducers from HBM. The machine can handle as many as 38,000 bottles an hour.

Baby milk bottles in this filling operation go on a carousel where they are filled, check-weighed, and moved out at high speed.


The baby bottler is manufactured by Krones AG, Moline, Ill. It incorporates 16 load cells in a single carousel for weighing. Empty bottles move into the rotating carousel, fill, get check-weighed and move out. Load cell transducers sample bottle weight during filling at a rate of 100 measurements/sec until the system detects the target weight.

One problem with this setup is vibration during filling. Either electronics must filter or adjust for the vibration, or vibrations must settle out before the weighing operation. Settling times are difficult to accommodate in the high-speed operations needed to hit production goals.

The weighing system is from HBM in Marlboro, Mass. FIT, or Fast Intelligent Transducer system, electronics let users download settings and adjustments to the weighing processes via a RS-485 serial bus. Up to 32 load cells connect to a single bus system, and all parameters store in EEPROM to guard against power failures.

The bottling machines use a type PW2/H3R4/10-kg load cell, which can make up to 100 measurements/sec. Each load cell sits in a stainless steel housing, hermetically encapsulated to handle the harsh environment of food manufacturing plants. The load cells don't need a trigger signal to initiate a measurement. The devices themselves offer a 2-kg tare load, a 300 gm to 2-kg life load, and a standard deviation of 0.5 to 0.7 gm.

Krones uses a similar weighing system on a soybean oil operation. Each of these filling machines has 72 FIT load cells per carousel. The machine can fill as many as 38,000 bottles/hr. The machine runs for 22 hr daily and needs only 2 hr for cleaning. This particular operation took advantage of the software program supplied with the load cells. The program was used to analyze the behavior of the filling procedure over time, which helped engineers in optimizing the mechanical system.

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