- Plant Managers
- Process Engineers
- Control Engineers
- Maintenance Managers
- Inventory Management
- Batching & Blending
- Weight Measurement in Industrial Manufacturing
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In almost every industry, raw materials and finished product need to be weighed multiple times in the manufacturing process.
Weighing vessels and silos is generally accepted as the most accurate and repeatable method to measure their contents, especially for inventory purposes.
A weighing system can take any of several forms but typically includes one or more load cells that support (or suspend) a weigh vessel or platform, a junction box, and a weight processor or controller. When a load is applied to the weigh vessel or platform, a portion of the load is transmitted to each load cell. Each cell sends an electrical signal proportional to the load it senses via a cable to the junction box. The load cell signals are summed in the junction box and sent via one cable to a weight processor or controller, which converts the summed signal to a weight reading. This weight reading’s accuracy can be affected by the system components’ quality and the system’s installation and operation in your environment.
The objectives are to provide the process with an accurate and stable weight reading, that updates fast enough for the process to be controlled effectively. Each scale needs to be able to be installed, configured and calibrated quickly and maintained – recalibrated and issues diagnosed easily.
INSTALLATION - There are many factors to consider in vessel weighing such as size, type of vessel, support structure, piping (isolation), vibration (movement), and environment (center of gravity, temp, wind, seismic forces) to name a few. For accurate weighing, the load cells alone must support all the weight to be measured. You can even hang vessels indoors above floor level, saving valuable production space, with the use of load points in tension.
CALIBRATION - The Traditional method used to calibrate and validate industrial scales can be very time consuming, costly, disruptive to production and/or place employees and the manufacturing supply chain at some risk. Usually the higher the capacity of the scale, the greater the impact to production lines. Some companies may be forced or elect to compromise the calibration and complete calibrations with a SPAN load less than the 80% of capacity, thereby deviating from the guidelines laid out for “best weighing practices”. The Traditional process usually takes a long time (hours). The larger the scale the longer it takes (hours and hours). This can drive production (OEE) down and costs up.
VIBRATION - To weigh a vessel as accurately as possible, it must be entirely supported by load cells with associated mounting hardware. If the vessel has an associated mixer or agitator that causes vibration, the weight processor or weight controller must exclude (separate and eliminate) the vibration information from the weight reading.
DIAGNOSTICS – Troubleshooting a weighing system can be time consuming. Often the components are out of reach or installed in enclosures that require specialized tools to open. If the load cells must be individually unplugged, checked and retested, the integrity of the whole system can be compromised.
Comparison of Calibration Methods
Traditional Calibration Methods
- Time Consuming – Scales need to be tested repeatedly to ensure accuracy and ISO comformance.
- Costly – Downtime, disruptive to production and people, affecting manufacturing supply chain.
- Higher Risk - The process can create unsafe conditions for operators and the person doing the calibration depending on the capacity of the scale being calibrated.
- Compliance - Calibration is traceable to certified test weights and instruments meeting requirements for Quality Management (e.g. ISO 9001).
Electronic Calibration – Hardy’s C2 Calibration
- Fast – Hardy C2 calibration can be completed without local test weights in less than 30 seconds.
- Reduce Downtime – this method helps to sustain or drive production (OEE) up and cost down.
- Increased Safety - Requires fewer test weights and provides safer conditions for operators and the person doing the calibration.
- Compliance - The calibration is traceable to certified test weights and instruments meeting requirements for Quality Management (e.g. ISO 9001).
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