Weighing is an essential process used in a variety of industries. From checking the correct number of items in a box to making sure that kegs and gas cylinders are filled, weighing is used across all stages of production.
It is crucial that all users follow proper weighing procedures to ensure accuracy and avoid error. Some factors that impact weighing precision include air currents, temperature changes, electrical interference and vibration, as well as static electricity.
Weight determination
It is important to thoroughly assess manual interventions in weighing processes before transitioning to automated systems. This helps reduce potential for gaps in efficiency that automation might introduce, and ensures that new weighing systems deliver the desired results. This process allows managers to recognize areas that would benefit most from the addition of automation and pinpoint inefficiencies that could be resolved by introducing automated systems.
For example, many manufacturers use a weighing system to measure the level of material in silos or tanks. This information is used to determine when it is time to reorder materials. In these applications, it is crucial that the weighing system be accurate enough to provide a highly reliable level indication.
The most critical factor in achieving this is the minimum weight threshold – a rule that dictates the accuracy that can be achieved with a particular instrument. This is different from legal tolerances, which consider only manufacturer specifications and do not take into account user-specific weighing requirements.
Check weighing
Check weighing is a common production process for food manufacturers. It allows you to verify that the product weight matches the label on the package and ensures compliance with government regulations. It also helps you minimize product waste and maximize plant efficiency.
A checkweigher is a static or in-motion scale that compares the weight of an item to a specific limit, usually based on your agreed product guidelines. If the product weighs outside of that range, it will be rejected from the line. It is commonly used in automated production lines to monitor the accuracy of filling systems and ensure that all packages are within tolerances specified by USDA/FSIS and NIST.
Weighing accuracy depends on several factors, including mechanical and environmental conditions. To prevent these factors from influencing your system’s performance, choose components that are specifically suited for your application and take steps to control environmental and mechanical forces acting on the equipment. For example, Hardy check weighing systems utilize vibration isolation technology to ignore the mechanical noise generated by conveyor belts.
Direct weighing
When a solid sample must be transferred to a container, it is important that the correct amount make it to the new container. Otherwise, it will remain on the weighing bottle rim or the beaker’s edge and produce an error in the weighed results. The tried-and-true method to avoid this problem is known as weighing by difference, or direct weighing.
To perform this weighing process, the empty balance is tared (reads zero with nothing on the pan). The weighing bottle or beaker is placed on the scale and then poured. The tared balance reading is then subtracted from the reading after the pouring to determine the exact mass of the sample.
This method eliminates the need for a container and also allows for a precise tare reading without having to manually subtract it. Exact zeroing is not essential because any errors in the initial weighing will cancel out when the two measurements are compared. This technique is especially useful in chemistry when accurate stoichiometry must be achieved.
Batch weighing
In addition to providing quality control and improved production efficiency, automated weighing processes save money. They also eliminate the need for excessive manual labor that can cause human errors and decrease production time. In addition, batch weighing systems provide precise measurements to meet regulatory requirements. This helps businesses avoid costly penalties and maintain product consistency.
The type of bulk material and its processing characteristics directly impact the weighing system design. Fragile powders, for example, require gentle weighing while denser granules may negatively impact a gain-in-weight system with tight variance targets. Flowability can also affect measurement. An experienced scale and blending systems provider can help select an ideal weighing system for a specific bulk material.
Dynamic weighing systems seamlessly integrate into fast-paced continuous processing equipment like extruders. This method enables rapid dosing and blending with no loss of accuracy. This is different from static weighing that measures at rest, which requires the material to be stopped and the vessel or hopper to be empty for accurate measurements.