1. Fragmentation:
Prescription factors:
① There is too much fine powder in the material, and the air cannot be discharged during compression. After releasing the pressure, the air volume expands, causing fragmentation.
② Improper selection or insufficient dosage of adhesive.
③ The drying time of the particles is too long and the moisture is insufficient.
④ Fragile materials and materials with large elastic deformation have weak bonding strength.
Equipment and process factors:
① Rapid compression is more prone to cracking than slow compression.
② Convex tablets are more prone to cracking than flat tablets.
③ Excessive pressure.
④ One time compression molding is easier to crack than second or third time molding.
⑤ The clearance between the punch and the middle die is small.
⑥ The wafer guide rail is worn and loose.
⑦ The deep concave punch rolls inward.
Resolvent:
① Use the pre pressure function to expel air from the material. Reduce fragmentation.
Specific application: Separate the main pressure and pre pressure, low-speed tablet does not form, adjust the pre pressure to make the tablet complete and tangible, without fragmentation, and without affecting weighing. If the tablet weight is qualified and the main pressure is applied, the hardness is qualified, and the tablet is pressed normally.
② Choose auxiliary materials with low elasticity and high plasticity. Choose adhesives with high viscosity (such as alcohol water solutions of PVP and HPMC). Increase the concentration or dosage of adhesive.
③ The ratio of fine powder to particles should be appropriate. No more than 5% for 80 mesh fine powder and no more than 15% for 65 mesh fine powder.
④ Select appropriate granulation methods.
⑤ Choose a suitable tablet press, adjust the speed and pressure appropriately. Replace the punching tool.
⑥ Improve material compressibility and reduce elastic recovery rate.
⑦ Adjust the height of the slide guide rail and tighten it.
2. Adhesive flushing
① The particles are not dry enough, the material is prone to moisture absorption, and the environmental humidity is high.
① Improper selection or insufficient use of lubricants.
② The surface of the punch is corroded and has a rough surface.
③ The font or carving of the punch engraving is too complex.
Resolvent:
① Control the moisture content of materials.
② Control the relative humidity of the compression environment.
③ Mix with lubricant (magnesium stearate+talc powder).
④ Replace or polish the punch.
⑤ Add dry fillers (calcium hydrogen phosphate, calcium sulfate, etc).
3. Pine flakes
① Poor adhesive strength (low adhesive dosage or low viscosity) cannot be overcome by increasing pressure.
② The pressure for pressing is insufficient.
③ The length of the punch is uneven. The main pressure wheel is worn and there are pits on the working surface.
④ The moisture in the particles affects the hardness, and the appropriate amount of moisture can increase the hardness.
Resolvent:
① Choose adhesive with high viscosity and increase the dosage.
② Increase pressure.
③ Use a punch with the same length as the upper and lower punches to replace the main pressure wheel.
④ Adjust the moisture content of the material.
Determination of material compressibility: The quality requirements for tablets can be achieved with relatively low pressure, indicating good compressibility of the material. Less wear and tear on the machine. When volatile oil is added, the binding force between particles weakens. After leaving it for a period of time and allowing the volatile oil to completely penetrate the particles, the compression effect will be better. Tablets generate temperature rise and heat under high pressure, and after the tablets cool down, their hardness increases. The factors that affect the hardness of tablets are related to the properties of the raw materials, including elasticity, plasticity, melting point, and crystal morphology (cubic crystal, flake like, needle like, dendritic), as well as the effects of pressure conditions, particle size, lubricants, adhesives, and moisture.
4. Exceeding the weight difference limit
① The particle size varies greatly, the flow rate is uneven, and there are many fine powders.
② The flowability of powder or particles is poor. The feeding mixer runs unstably or at a slow speed.
③ The downward stroke length is inconsistent. The damping force of the downward movement is inconsistent.
④ The amount of material in the feeding hopper varies.
resolvent:
① Particle uniformity, with appropriate proportion of fine powder.
② Adjust the prescription and add fillers with good fluidity. The speed of the feeding mixer is appropriate.
③ Select a consistent length of punch and adjust the damping force of the punch.
The magnet or damping pin is in contact with the downward thrust to ensure that its resistance force to the downward thrust is appropriate and uniform. The dust ring is installed at the upper opening of the punch hole on the lower punch plate, providing a surrounding force for the lower punch. The magnet or damping pin, together with the dust ring, forms a certain damping force for the downward thrust, enabling it to run steadily at high speed on the undulating track. The consistency of the downward thrust running state and the consistency of the downward thrust length have an impact on the weight of the sheet.
5. Delayed disintegration
① Excessive pressure leads to excessive hardness of the tablets.
② Excessive use of hydrophobic lubricants.
③ Excessive use of adhesive or strong stickiness.
④ Improper use of disintegrants, improper dosage and addition method.
Resolvent:
① Reduce pressure appropriately.
② Using hydrophilic or water-soluble lubricants (micro silica gel).
③ Reduce the concentration and dosage of adhesive.
④ Using highly efficient disintegrants (such as cross-linked polyvinylpyrrolidone, cross-linked carboxymethyl cellulose sodium, carboxymethyl starch sodium, low substituted hydroxypropyl cellulose).
6. Exceeding the dissolution limit
Tablets do not disintegrate, particles are hard, and drug solubility is poor. According to the actual situation, surfactants can be added to solve the problem.
7. Discoloration or flower spots
① The particles are soft and hard -------------------- Reduce particle hardness.
② Contact with metal ions ------------------- The bottom of the feeding tray must not have friction with the turntable.
③ Soluble components migrate. Choose insoluble pigments.
④ Pollute the tablet press with oil stains and accumulate scale on the punch. Cleaning machines to remove oil stains and colored tablets should use ethanol as a wetting agent for granulation (without starch slurry).
8. Watermark or polka dot
① Improper use of lubricants or adhesives.
② Particles become damp and hard* We need to address the reasons and solve them.
③ Uneven drying of particles; Punch engraving, etc.
9. The edges of the tablets have large burrs
① The punch is worn. Long term use of punching tools and poor compressibility of materials result in a decrease in the diameter of the punch, causing the middle die to be squeezed and ground into a large belly shape, resulting in excessive clearance between the punching tools and the appearance of burrs.
② The moisture content of the material is too high.
Resolvent:
① Changing the position of the tablet in the middle mold can be achieved by adjusting the translation handwheel.
② Swap the upper and lower parts of the middle model for use. Or replace the punching tool with a new one.
③ The moisture content of the material should be reduced.
10. Uneven or deformed punching tools
Uneven length during upward movement can cause loose pieces, while uneven length during downward movement can result in significant differences in piece weight.
reason:
① The wear and tear caused by long-term use can result in uneven length.
② When the machine is stopped for a long time, the main pressure should be reduced. Otherwise, the punch may deform due to long-term high pressure, especially for thinner punches that may become shorter and thicker, affecting the use and tablet quality.
③ Inconsistencies in the length and thickness of the downward punch not only result in significant differences in chip weight, but sometimes also trigger an alarm and shutdown when the downward punch is too tight.
Attention: After using for a period of time, the surface and length of the punch should be checked, and the difference in length should be within 0.05mm.
11. Powder omission
① There is a lot of fine powder in the material.
② The gap between the feeder and the turntable should be as small as possible, preferably between 0.04 and 0.06.
③ The copper bottom of the feeder is worn and has grooves, which can also cause powder leakage. Replace the copper base.
④ The scraper plate should be in close contact with the turntable, and the powder return ring should be in close contact with the turntable.
12. The machine vibrates greatly
① Particles that are too hard force the machine to operate under high load conditions, which is harmful to the equipment. Should be re pelletized.
② During operation, there is regular vibration and bouncing during downward thrust. Adjust the downward thrust resistance force.
③ The connecting rod nut between the upper and lower main pressure wheels is loose, and the clearance between the screw threads is large.
13. Difficulty initiating
It is difficult to start after stopping halfway, mainly due to excessive pressure. The main pressure should be reduced to achieve light load starting. It is advisable to be able to turn the car by hand.
14. Alarm for punch being too tight
When pressing at high speed, if the upward movement is not flexible and the downward movement is too tight, the protection switch will activate and the machine will stop with an alarm to prevent clogging. The reasons for excessive tightness during upward flushing are often due to damage to the flushing surface, insufficient lubrication, and excessive oil sludge.
Alarm when there is sticky impact during downward flushing, manifested as hardened powder sticking to the circumference of the punching tool, increased resistance to upward and downward movement, and easy damage to the slide guide rail and difficulty in removing the punching tool.
15. Wear of the upward guide rail disc
The wear of the guide plate mainly occurs in the upward climbing (lifting) section, where the lack of lubricating oil is the main reason. During the operation of a circular punch, there is a self rotation motion, while an irregular punch has no self rotation and is subject to friction between a fixed point and a guide rail. Therefore, lubricating oil is indispensable. Punching is dirty, circular punching cannot rotate, and it will also wear out the punch cap and guide rail. This is also the main consideration factor for the lower pressing speed of irregular punch compared to circular punch.
16. Difficulty adjusting hardness handwheel
The moving plate of the lower main pressure wheel cannot rotate, and it is mostly stuck due to the entry of medicinal powder. It needs to be disassembled for cleaning.
17. Abnormal heating of the punching tool, with deep abrasion marks on the bottom surface of the punching cap
The bearing of the lower main pressure wheel was clogged with powder, and the pressure wheel could not rotate. The surface of the punch and pressure wheel were hard worn, resulting in abnormal heating of the punch. Remove the main pressure wheel, clean and inspect the wear level of the bearing and pressure wheel surface.
18. During tablet pressing, there is a phenomenon of the disc being lost or rotated
The main shaft and punch plate of the tablet press are fixed by the spring expansion ring. When the spring expansion ring breaks or the locking nut becomes loose, there may be a phenomenon of losing rotation. The spring expansion ring and locking nut should be replaced.