Filling scale

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Filling scales (or also dosing scales ) are automatic scales that are used to weigh dry raw materials / products. Typical areas of application can be found in the food industry, in pharmacy and in the automotive industry.

construction

General structure of a filling scale

The general structure of a filling scale differs only slightly from manufacturer to manufacturer. A filling scale usually consists of the following components:

  1. Storage hopper - for storing the product to be filled
  2. Vibration drive with attached vibration chute - for conveying the material into the load tray
  3. Load pan - this is where the actual weighing process takes place
  4. Weighing system - depending on the version / requirement, a strain gauge or a compensation load cell
  5. Discharge funnel - feeding the weighed product into a manually provided container (e.g. cans or bags)
  6. Machine frame / machine housing - to accommodate the components

functionality

General

There are both semi-automatic and fully automatic filling scales. The design is based on the specific requirements of the production process and is not subject to any fixed rules. For the sake of simplicity, the functionality of a semi-automatic version is described below.

Before a filling scale can go into operation, the product must get into the storage hopper. This can either be done manually or automatically using a suitable conveyor system (e.g. vacuum conveyor ). The product height on the vibrating chute is then adjusted using the slide on the storage hopper. In this way, a uniform product flow is generated in the later dosing process. The target parameters must now be specified via an operator terminal. Which these are varies depending on the machine manufacturer. They essentially depend on the control of the system. Are u. a .:

  1. Target weight
  2. upper tolerance
  3. lower tolerance and
  4. the throughput per minute.

Once the setting has been successfully completed, the actual filling process can begin. The vibrating chute conveys the product into the load tray, which is attached to a weighing system. Material is conveyed until the target weight is reached (taking into account the permissible tolerances). Now the weighing system sends a completion message to the control, so that either the operator can call up the finished filling (e.g. via a foot switch) or the load tray opens automatically. After the request has been made, the product passes through the discharge funnel into the container provided by the operator. As soon as the load pan is closed again, the dosing process starts again.

Example of a semi-automatic filling scale

requirements

In order to be able to dose products with a filling scale, they must meet certain requirements. As a rule, all dry, flowable and free-flowing materials can be filled ( see areas of application ). Merely sticky or lumpy products would cause an inhomogeneous product flow and thus deliver poor dosing results. In simple terms, it can be said that powder, granules and pourable materials can be reliably weighed with the help of this technology.

control

Both the weighing system used and the control of the dosing are decisive for the speed and accuracy of a filling scale. In addition to the classic two-point control for the coarse and fine flow, there are computer-aided systems that permanently determine the required speeds for the coarse and fine flow of the vibrating channel. This considerably reduces the setting effort, as the system searches for the necessary parameters itself, even with the most varied of products. With two-point control, on the other hand, the two speeds are usually set manually using a potentiometer . The filling scale is only given up to what weight the speed for the coarse flow is to be used. The fine flow then follows until the target weight is reached.

Areas of application

The following materials / products can be weighed with a filling scale. The actual area of ​​application is significantly larger and extends over many subject areas.

food industry

  1. coffee
  2. Spices
  3. cereal
  4. tea

powder

  1. Metal powder
  2. Dyes
  3. Active pharmaceutical ingredients
  4. Food supplements

Chunky products

  1. Capsules and tablets
  2. Metal parts
  3. Plastic parts
  4. cork

literature

  • Manfred Kochsiek (Ed.): Handbuch des Wägens , 2nd edited and expanded edition, Springer Fachmedien Wiesbaden, Braunschweig 1989, ISBN 978-3-322-90574-1
  • Dr.-Ing. Dirk Dreschel and Dipl.-Ing. Franz Vetter: Weighing, Filling and Packaging Processes , 2nd, completely revised edition, Oldenbourg Industrieverlag Munich, Munich 2008 ISBN 978-3-8356-3131-1