Batch weighing is a manufacturing process that is used to mix multiple ingredients and form a final product. Sometimes the process is fully or partially automated. In this process, the quality of the finished product is often directly related to how closely the manufacturer follows the formula. This is especially true for sensitive formulas used by chemical and pharmaceutical manufacturers.
Types of Batch Manufacturing
Food processing is one of the most common kinds of batch production, where each group of items moves through each stage of the production process together. Baked goods are almost always produced in batches since they generally don’t have a long shelf life and must be sent to local markets fresh.
Batch manufacturers usually fill orders on a case-by-case basis. So if a chain of grocery stores puts in an order for five hundred loaves of a specific brand of cinnamon raisin bread, the manufacturer will set up the equipment to manufacture that order.
They would have several vats, each including the ingredients required to make the bread. For example, they would have vats of flour, sugar, baking powder, cinnamon, raisins, water, yeast, etc. Dispensers equipped with scales will measure out the precise amount of each ingredient required by the formula and pass them into another vat where they will be mixed together into dough.
Once the dough has finished rising, it will be split into loaves, placed on a baking tray, and sent through the oven. Once cooled, they will be packaged and distributed to the store.
The major difference between this kind of batching process and one where chemicals or pharmaceuticals are manufactured is the level of accuracy required by the scales. No one’s going to care if they get a few extra raisins in their raisin bread, but too much or too little of an ingredient in a prescription medicine can mean serious health risks for the person whose health relies on that medication.
But what kind of scales can provide the sensitivity required by these painstaking manufacturing processes?
Arlyn Ultra Precision Scales
The difference between standard scales used in batching processes and our ultra precision scales lies in the kind of transducer used. To understand what makes our ultra precision scales special, it’s important to understand standard weighing technology, which utilizes strain gage load cells.
Strain Gage Load Cells
Load cells feature resistors called strain gages. These are adhered to a piece of metal, known as a load cell, which is attached to the underside of the scale platform and the floor of the scale. Four thin sections of the load cell, called flexures, are incorporated into the spring element. The strain gages, which measure the stress placed on an object, are then wired together to form a Wheatstone’s bridge.
When weight is applied to the platform the spring element bends, causing the flexures to bend, which causes a change in the resistance of the gages. This change in resistance also changes the voltage output of the bridge. This voltage is sent through an analog-to-digital converter, where it is translated into numeric form and sent to the digital indicator, where the weight value is displayed.
Depending on the capacity of the scale, strain gages generally provide a resolution of one part in five thousand pounds. Therefore, there is a trade off between sensitivity and the capacity. The higher the capacity, the lower the sensitivity. Chemical and pharmaceutical formulation requires extremely high sensitivities.
Surface Acoustic Wave (SAW) Load Cells
Our ultra precision line of scales use a similar theory for spring element design, but use a different kind of transducer to take weight measurements. Rather than strain gages, two surface acoustic wave, or SAW, transducers are affixed to the spring element. One transducer is a transmitter, while the other acts as a receiver. When a load is applied to the platform, the SAW wave created by the transmitter travels to the receiver, is amplified and fed back to the transmitter.
The distanced between the transducers is directly correlated to the weight of the load on the platform. Because we know how far apart they are at rest, we can determine the weight of the load on the platform by determining how the distance between them changes. When the distance changes, so does the frequency of the wave passing between the two transducers. Our ultra precision load cells measure this frequency and display the weight of the object.
The resolution afforded by these scales is ten to twenty times better than what strain gage scales can achieve at one part in one hundred thousand. This means a five hundred pound capacity ultra precision scale can display measurements up to 0.005 pounds, while a strain gage scale at the same capacity can only display measurements up to 0.1 pounds. A ten pound capacity ultra precision scale provides measurements up to 0.0001 pounds, while a strain gage scale with the same capacity will only display weights up to 0.002 pounds.
So when it comes to chemical and pharmaceutical formulation, where even a few grains of powder or a couple drops of liquid can affect the consistency of the final product, SAW technology can make all the difference.
Contact Arlyn Scales Today
Arlyn Scales is a US-based, factory direct manufacturer. Not only can we provide you with weighing solutions sensitive enough for delicate formulation, we can customize the design to fit an existing assembly line or for easy incorporation into your system design. To discuss your unique needs and learn more about our Ultra Precision Scales, contact us today. Our customer support staff is standing by to help guide you to the scale that actually meets your needs and your budget. Don’t forget to ask about our optional automation equipment and our data collection software.