How to Avoid Errors During the Weighing Process

Weighing is a critical part of food manufacturing applications. Accurate weighing can help ensure that finished products look and taste the same.

Process weighing involves using load points to dispense and monitor powdered materials. Unlike traditional scales, these systems can be designed to detect changes in weight with very little noise.

Plan the Weighing Procedure

An important part of weighing is the preparation of the weighing work area. It must be clean and free of debris and spilled materials. It should also be well ventilated, if necessary with an air filtration system, especially for hazardous substances such as fine powders. These materials can create static charge that causes erratic weighing measurements. An antistatic device may be necessary to eliminate the charge.

The weighing workstation should also be kept at a constant temperature and the balance, objects to be weighed, and reference standards should be in thermal equilibrium. If not, convection currents will affect the readings.

During production, a fast and accurate checkweighing process can dramatically reduce your rejection rate and save you money. Many weighing systems incorporate data tracking capabilities that can help you see trends in your results such as a high rejection rate in one day or a certain product being consistently over/under the target weight. This information can be analyzed and used to improve quality and increase productivity.

Assemble the Proper Equipment

During the weighing process, it’s important that all equipment used is of good quality. This includes the weighing instrument, the piping that conveys the material to be weighed, and any other components in the system such as a forceps, pipets or spatulas of proper size. It’s also essential that the correct containers be used, with each container having a capacity that does not exceed the weighing instrument’s loading capacity.

A top-quality load cell is a piece of machined metal that bends due to the mechanical force of the sample and senses the strain through points on the cell with strain gauges. This information is converted into an electrical signal that the weight controller reads.

Process weighing is an essential technology for many different applications. For example, it can be used to continuously monitor a silo level or inventory, to discharge material by weight or rate, or to measure and control flow. See how Siemens weighing solutions can help improve efficiency and productivity by reducing waste in your process plant.

Place the Sample on the Balance

Once the proper equipment and materials are gathered, the sample can be placed on the balance. It is always a good idea to check the condition of the balance first. It may have been turned off or left in a different state by the previous user. If this is the case, it must be ‘tared,” or reset to read 0.0000 g by pressing the Tare button.

It is also important to avoid handling objects that will be weighed with bare hands, since hand grease can cause errors in the readings. It is preferable to use clean forceps, tweezers or pipets for handling the specimen.

Process weighing is used when the measurements will be repeated in a controlled setting, such as continuously monitoring a level or inventory of material in a silo, discharging materials by weight or rate, or blending and measuring batch quantities. For these applications, the stability of the process and accuracy requirements will influence the choice of measurement method.

Record the Readings

While many errors can be eliminated through proper procedures, there are a few errors that cannot be completely avoided. However, there are steps that can be taken to reduce them during the weighing process.

For example, it is important to calibrate the scale on a regular basis, preferably daily. This ensures that the effect of gravity is properly accounted for and the accuracy of readings remains consistent across geographic locations. Additionally, it is essential to tar the balance and shield it from environmental factors such as temperature and humidity.

Michelli Weighing & Measurement incorporates data tracking capabilities into our weighing systems to automatically record information during the weighing process. This data can then be viewed on a computer, saved or pushed to a URL for real-time monitoring. By reviewing this data, managers can quickly discover inconsistencies within a batch or manufacturing process and make corrections to prevent future problems. Ultimately, this can save time, money and improve product quality.

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