Working Principle Of Auto Coater Machine

The auto coater consists of a control system, a hot air filtering system, coating pan, solution tank, and exhaust system. The film to be coated on the tablet is in liquid form before the process is started so the liquid is filled in the solution tank. The liquid is stirred well in the solution tank and then pumped into the coating pan. The coating pan is perforated and holds a batch of tablets that are to be coated. A set of spray guns are present at the center to spray the coating liquid on the tablets. The coating pan is able to rotate on its axis.

Hot air is passed in from a hot air blower which is passed through a series of filters to remove impurities. The filters used are a washable filter, pre-filter, and HEPA filter. The air from the blower is not hot initially so a steam heater is used to heat the air before passing it into the coating pan. The machine is operated by PLC controls from the control panel.

In the coating process, the tablets or similar products that are to be coated with film coating are filled in the coating pan. The coating liquid is pumped from the solution tank into the coating pan. The spray guns spray the tablets with atomized particles of

the coating solution as the perforated coating pan is rotated so that the entire batch of tablets is evenly coated. Simultaneously, the hot air from the blower is passed in to the drum at negative pressure which dries the sprayed coating evenly and rapidly which then causes it to become a solid and smooth surface film on each of the tablets.

The air is then exited from the perforated coating pan and moves to the exhaust system. The exhaust system consists of an exhaust blower to send the exit air from the coating pan to the external environment. The exhaust system consists of a dust collector which is also called a scrubber. In some systems, wet scrubbers are used to filter the particulates in the exhaust. The liquid droplets within the wet scrubber absorb the particulate matter thereby filtering the exhaust air before release.


what is the auto coating?

Auto coater or automatic coating machine is an apparatus that is used to coat surfaces of small particles with a thin film of coating substance.

In pharmaceutical industries the auto coater is used to coat the tablets. The tablets are sprayed with a coating as the tablets move on in a device and then hot filtered air is passed so that the applied coat dries immediately to form a thin layer of coating on the tablet surface.


It is the application of coating solution to the rotating bed of tablets with the application of hot air to facilitate the evaporation.


A compound or multiple layer over the tablet or granules is called coating.



  • Auto-Coater is used in pharmaceutical industries for coating of tablets.
  • In food industries candies are coated with sugar using auto coater.
  • Various types of coating are possible like film coating with an organic solvent, enteric coating, and aqueous coating.
  • Film coating to cover the unpleasant taste of tablets.


PartsAuto Coater Parts Installation Advantages Features Specification

  • Automated Control System
  • Electric Motors
  • Touch Screen Operation Panel
  • Guide Plate
  • Peristaltic Pump
  • Spraying System
  • Pan Cooling Surface
  • Auto Coater
  • Spray guns are the major parts of any auto coaters that are used in the industry


Installation of Auto coater

  • The auto coater is placed in the allocated location in the process area.
  • Power connections for the functioning of the equipment are done.
  • Connections for air inlet and outlet are made.
  • The liquid to be coated is filled in the liquid container and then the machine is turned on.
  • The rotational speed of the machine is adjusted.
  • The working temperature and pressure of the process are maintained and controlled externally as per the requirements.


Advantages of Auto-Coater

  • Clean and automated coating system which prevents and dust entry into the coating zone.
  • The production rate is very high due to the high degree of automation.
  • Reduced weight of the final product because of thinner film coating compared to other coating types.
  • Allows easier consumption of product due to film coating. o Flexible batch operations are possible.
  • The film coating increases the effective period of the drug.



  • User-friendly control and operation by modern control systems.
  • High atomizing and flexible spray guns for the coating process.
  • Spraying is done from different angles as per requirement.
  • High tech control systems to regulate the temperature and pressure conditions within the coating zone.
  • Viewport for visual observation of coating process.
  • The perforated pan has larger openings for a high-quality coating finish.
  • Dust collection system for exhaust air having scrubber, exhaust blower, and filter.
  • Some auto coaters have a rotating perforated drum for moving the particles while the coating is done.


Safety Features

  • The auto coater has Overload pressure release mechanism.
  • The auto coater has Emergency stop button.
  • The auto coater has Separate production and technical areas.
  • The auto coater has Perforated pan designed to prevent breaking up of tablets during rotation.



Pan Diameter,  Approximate Working Capacity, Pan Mouth Diameter, Pan Speed,  Main Drive Motor, Inlet Air Blower Motor, Inlet air, Steam Consumption,

Compressed Air is the important parameter considered for the construction of any auto coater.

The working capacity of the auto coater ranges from 30 kg per batch to 500 kg  per batch.