From the initial weighing of raw materials to the final packaging of finished products, a food manufacturing company requires a consistent and precise weighing process. A good weighing process ensures product quality and safety guidelines are maintained throughout production.
Weighing instruments require a draft-free location, a stable bench, and calibration weights to maintain accuracy. Also, be sure to handle the instrument with clean hands to avoid fingerprints.
Weighing Equipment
Weighing equipment is used to increase efficiency and safety in a variety of industries. From the food and beverage industry to pharmaceuticals, medical devices and manufacturing, weighing equipment is necessary for accurate measurement and process control.
The type of scale required is based on the job it needs to do. Home scales work off of springs, while industrial scales can be digital or mechanical and range from platform bench scales to crane and truck scales.
The basic form of a balance is similar to a teeter totter and works on the principle that an unknown mass in a scale pan suspended from one end of a beam is balanced by a combination of known masses in scale pans or a slider weight on a linear, dial or digital display indicator. All approved scales and balances must carry an indication of accuracy which is usually found printed or stamped into a lead plug in the base. This will normally include a six-pointed star and show that the equipment was inspected and approved by trading standards services.
Weighing Procedures
Weighing is used throughout the food manufacturing process, from tracking raw materials to ensuring products are safe and high-quality. Whether you run a huge food production facility or operate a small restaurant, the quality of your product depends largely on how your weighing equipment is used and calibrated.
The way standard objects weighed are handled can significantly affect their masses. Touching the weights with bare hands leaves grease and oily films that will affect the mass at the time of measurement. Handling weights with clean forceps or a spatula of the correct size is much better.
Analytical balances are very sensitive instruments and should be operated carefully. It is best to place all weights gently in the center of the weighing pan/platform and to avoid shock loading. Dials on mechanical balances should be turned slowly and cautiously to improve repeatability. Avoid exposing the weighing system to sudden temperature changes and vibrations, and ensure it is located away from heating/cooling vents.
Calibration
Calibration is the process of adjusting an instrument to match the precision and reliability of a reference standard. Instruments can drift over time due to factors such as vibration or varying temperature and calibration removes this deviation.
Applied at the factory level, calibrating allows for savings in energy and raw materials, reduced production delays and stoppages, increased equipment longevity and optimal quality of product. Additionally, strict regulatory requirements often require traceable calibration.
Traceability refers to the ability to trace the lineage of a calibration to the primary standards maintained by a National Metrology Institute (NMI) in a given country. The BIPM works directly with NMIs to help pass down the SI for the purpose of scientific discovery and innovation, industrial manufacturing and international trade. The BIPM also maintains primary standards for several of the main SI units as well as some important derived SI units such as pressure (Pounds per Square Inch or PSI). This is referred to as the calibration pyramid.
Recording
A weighing process requires proper recording of the results. This includes recording the date and time as well as a summary of all the recorded values. A standardized method for applying significant digits and rounding techniques ensures consistency in measurement results and enables valid decision-making using data.
This includes recording that the balance is level, and that it is free of debris or foreign objects. It also includes ensuring that the weighing pan is clean and dry. For corrosive or volatile chemicals, a plastic weighing tray or other container may be required to prevent contamination of the weighing pan surface.
Weighing devices can be connected to a computer using a data cable and software for transferring the recorded weight with date and time to a file. RS-232 cable, USB virtual COM port or Bluetooth SPP (standard protocol) are the most common choices for connecting scales and balances to computers. Simple Data Logger (SDL) is software designed to send the weighing data with date and time from a scale or balance to a file, optionally adding the current date.