Coating Machine in Pharmaceutical Industry
Coating machines are divided into two types
- Standard pan
- Perforated pan
Basically, the coating process depends on 3 basic elements:
- Temperature
- Pan speed
- Spray rate
Firstly, Temperature
There are two very important components in any coating machines:
- Inlet air
- Outlet air
There are two fans, one responsible for entering air into the machine (inlet air fan), and before it is a HEPA filter to purify the air and be connected to steam and heat cooling, and the amount of air entering the machine is controlled, which is one m3 per hour.
A fan is responsible for removing air saturated with powders and lost spray from the machine, and there are filters between the fan and the machine to trap the powders from the motor, collect them, and dispose of them.
At the top of the machine there are air entry and exit hoses and gates to control the rates of air entry and exit.
In the old machines, the air entry point was at the top of the tablet bed, but currently most modern machines have the air entry and flow location at the bottom of the tablet bed, and this is better for speeding up the drying process
There are two ways to control temperature in coating machines
1: Control of inlet air temperature.
2: Control of the outlet air temperature.
The first method is the best to control the input temperature
This means that the amount of incoming air and the temperature of the incoming air are controlled through the control panel, and I can supply them until the temperature of the tablets reaches the required temperature.
The second method is that the machine automatically controls the amount of air and heat entering the machine in order to achieve the required temperature for the tablets meaning if you want to operate at a temperature of 42, for example, the machine adjusts itself in order to give you the temperature without any control from you.
An important thing regarding the issue of air is the pressure difference. There must be a negative pressure difference inside the machine.
There is (suction) and in order to achieve this, the power of the suction motor must be higher than the power of the motor controlling the air entry so that the process of pulling out the dust takes place immediately and does not accumulate inside the machine.
Secondly, the speed of the pan
The drum contains baffles, which are the arms responsible for turning the tablets . They have many shapes and sizes, and in some machines the possibility of changing the baffles depends on the size of the patch inside the drum.
The shape and design of the baffles is very important because they are responsible for the movement of the tablets inside the pan, and very many problems can occur due to poor design of the baffles.
Thirdly, spray rate
The spraying process depends on 3 elements
- Pump
- Solution and air hoses
- Guns
The pump is a peristaltic pump, and this is a pump that has a compressor wheel inside a box that presses the silicone hose to withdraw the solution, and this is the only and main reason for pump the solution, and there are no other factors..
The hoses inside the pump have different sizes and diameters depending on the type of solution and its viscosity and according to the spray rate you need, meaning if you need a small amount of solution, the smaller size hose is preferred.
There are special type hoses designed for some solutions, such as solutions in which acetone & metheline coloride are used, to withstand them for a longer time.
Spray guns
The gun consists of a needle, a nozzle, and an external cover with air exit holes. Guns are connected to four hoses, and some guns have three hoses. These are the definitions of hoses connected to guns.
- AA : Atomizing air (responsible for pumping the solution)
- PA : Pattern air (responsible for distributing the solution)
- CA : Control air (responsible for operating the gun)
- L : Liquide hose
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Resource Person: Shady Mansour
