Common Failures of Rotary Tablet Press and Solutions(Part 2)

2.4 Adjusting System


Adjusting system includes pressure adjustment and filling depth adjustment.

①Adjustment malfunction. In general cases, adjustment malfunction is closely related with the hand-wheel and turbine. One possible cause is loosening of screws of hand-wheel, which makes the hand-wheel couldn’t work. Another possible cause is that the adjusting turbine locked.

②Unstable filling. Possible reasons are as follows:

  1. Materials are not uniform and with poor fluidity;
  2. Abrasion of punches and dies makes the shape or the thickness of tablets a little different from time to time;
  3. Hopper is fixed at an improper position, and insufficient materials flow into feeder;
  4. Front filling track gets severe worn, which causes punch skip. You just change the filling track;
  5. Lift pole gets badly worn, resulting in large clearance thus causes vibration of filling track. Solution is to to replace the worn components;
  6. Undersurface of feeder gets serious worn, leaving uneven clearance between feeder and turret;
  7. Scraper gets badly worn, leading to uneven filling. Solution is to replace a good scraper.

③Loosening tablets and unsightly tablets. The causes of such defect tablets may be low pressure, uneven particles. It is better to increase pressure by adjusting hand-wheel and adjust the material formula, including the ingredients.

④Vibration and loud sound occur when it works. It is because unbalance of pressure from both sides. you should adjust the pressure promptly.

2.5 Feeding System

Feeding system includes feeder and hopper. Common faults and solutions are introduces as follows.

①Powder leak. Powder leak is generally caused by the large clearance between scrapper, undersurface of feeder, and turret. All you need to do is to control the clearance in an proper range. Large clearance will cause powder leak, while small clearance will give rise t abrasion of rotary table.

②Overflow or inadequate of materials. No matter for the overflow or inadequate of materials, the reason is mismatching of the material fluidity and speed of turret. You should adjust the turret speed in accordance to the material fluidity.


2.6 Overload protective system

Common fault of overload protection system is frequent alarms for overload pressure or low set pressure of overload protection spring. Therefore, two ways to avoid frequent alarms. One is to adjust hand-wheel to reduce load pressure. The other is to increase the set pressure of overload protection spring.

2.7 Reduction gearbox

Reducer is composed of worm wheel, worm and housing. Oil leakage of reducer is one of the common faults, which can be resulted from loosening of flange screws and aging of oil seal. Then the solution comes that Tighten up the flange screws or replace the oil seal and apply sealant.

2.8 Punches and dies

Punches and dies are the quickest-wear parts, and common failures are listed as picking&sticking, capping, chipping, lamination, weight variation, double impression, etc. These are more likely to be caused by improper material formula. Plunger is also the most active part like guide way. Large friction and abrasion damages them. Try to do more or regular lubrication to avoid severe worn.

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