Causes and countermeasures of unstable filling volume of filling machine

In recent years, CFDA has continuously improved drug standards, making pharmaceutical companies more stringent requirements for filling machines. Filling accuracy is the first element to express the performance of the filling machine, it directly affects the quality of the drug, the stability of the filling accuracy is an important guarantee for the production of qualified drugs. In view of the phenomenon of unstable filling capacity in the ceramic pump filling system in the filling and stoppering machine, the reasons can be analyzed from two aspects of mechanical structure and electrical control, and solutions are proposed. 

Reason Analysis 

Mechanical structure 

The mechanical structure of the filling system is as follows:

  1. Liquid dispensing system: used to transfer the prepared liquid medicine to the dispenser or liquid medicine bag. 

  2. Dispenser: integrated buffer tank and closed liquid separator. The following table is the configuration method of the commonly used liquid dispensing system of Truking Technology.

  3. The filling part is mainly composed of rotary valve motor and drive unit, multiple sets of filling motor and drive unit, transmission gear, roller screw and ceramic pump. 

  4. Needle frame structure: used for tracking and positioning bottles for corresponding filling. 

Electrical Control 

The filling is carried out by the absolute position control mode of the servo motor, which can be precisely positioned. When the servo motor does not reach the specified position, the servo motor will alarm and stop the filling and equipment; at the same time, the control of the rotary valve is the same as that of the filling pump; there is also the control of the reciprocating and lifting of the needle frame, the above three points are all electrical. control. 

Countermeasures 

From the above, the inaccurate filling volume is generally caused by dripping or bubbles, and the main reasons and countermeasures for dripping and bubbles are as follows: 

1. Non-metal materials are not selected for the sterilizer. During sterilization, the pump rod is in contact with the metal material, and the metal material is stuck on the pump rod, which is easy to cause wear of the pump rod, poor air tightness, and bubbles during the filling process. Solution: Try to use special sterilization equipment.

2.  When the pump is installed, the pump body and the pump rod are mixed, and the clearance of the pump does not match, which is easy to cause wear of the pump rod, poor air tightness, and air bubbles during the filling process. Solution: The pump body and the pump rod are labeled and not mixed.

3. The installation position of the liquid storage tank, liquid separator, ceramic pump and needle holder, the height difference between the installation position of the buffer tank and the installation position of the ceramic pump is too large, and the pressure of the ceramic pump on the liquid medicine is too high, which may easily lead to needle irrigation Drops. Solution: Minimize the height difference of the installation positions of each component as much as possible. If it cannot be reduced, add another buffer device between the buffer tank and the pump.

4.  Bubbles or drips will occur if the connections between the silicone tube, the dispenser and the ceramic pump are not tightened; Solution: Add an inspection before each start-up. If the above situation occurs, replace the connector or silicone tube immediately.

5.  The connection slipknot between the ceramic pump and the rotary valve shakes too much or the verticality of the pump is wrong, resulting in dripping; Solution: Increase the number of tests each time the pump is installed. If the connection slipknot shakes too much, it is recommended to replace it.

6.  The rigidity of the filling servo motor itself is insufficient, resulting in slight shaking of the ceramic pump in the later stage of filling, resulting in dripping. Solution: Manually adjust the rigidity of the servo motor until it is suitable.

7.  The filling speed is too fast, resulting in excessive pressure of the silicone tube, resulting in dripping. Solution: You can reduce the filling speed, change the acceleration and deceleration of the filling pump, or replace the silicone tube with a thicker wall.

8.  The length of the needle holder and the silicone tube is too long, resulting in excessive shaking, resulting in dripping. Solution: fasten the needle holder, if it cannot be fastened, replace the fastener, reduce the length of the silicone tube as much as possible, if it still shakes, add a fastener in the middle.

9. Due to the excessive setting of the suction volume, the medicine liquid will return to the silicone tube, and it is easy to generate air bubbles at the needle port when filling next time, thus affecting the filling volume (mainly for small-sized products). Solution: According to different pharmaceutical processes, add different formulas of resorption volume, and call different formulas of resorption volume under different circumstances.