Nom des pièces de la machine d'enrobage de comprimés

Tablet coating machines put a thin layer of material around finished tablets. Film coating, sugar coating, enteric coating. The machine handles it. But knowing the tablet coating machine parts name for each component helps when something needs replacing or when you’re troubleshooting a coating defect you can’t figure out.

Most modern coaters are perforated pan systems. Some older operations still run standard pans. Either way, the core parts are similar. What follows is every major part on the machine and what it does.

1. Coating Drum (Pan)

Heart of the machine. Big metal drum sitting horizontal, spinning on its axis. Tablets go inside, tumble around, and get sprayed with coating solution while hot air dries everything.

Perforated drums have holes punched through the shell. Drying air passes right through the tablet bed, which is why these machines coat faster and more evenly than solid pans. Solid pans rely on air blowing over the top of the bed, which is slow and less uniform.

Baffles welded or bolted inside the drum keep the tablets mixing. Without baffles, tablets just slide around in a mass and the ones in the middle never see the spray. Baffles lift them and tumble them so every tablet gets exposure.

Drum bearings, the drive motor, and a gearbox spin the whole thing. Bearings wear. Gearboxes get noisy. Motor overloads happen if the drum is overcharged with tablets. All of it needs checking during PMs.

Some drums have a variable speed drive so operators can slow down for delicate tablets or speed up for tougher ones. If the VFD faults, the drum either stops or runs at one fixed speed. Neither is ideal mid-batch.

Drum size sets your batch capacity. Bigger drum, more tablets per batch. But running a big drum at low fill level means tablets don’t form a proper bed and coating uniformity drops. Match the drum to the batch size or you’ll fight quality problems constantly.

2. Spray System

Spray guns sit on an arm inside the drum and mist coating solution onto the tumbling tablets. Gun-to-bed distance matters a lot. Too close and you get overwetting. Too far and the droplets dry before they hit the tablets.

Either way, the coating comes out bad. Logos fill in, edges get rough, and you’re reworking or rejecting tablets.

Each gun has a fluid nozzle, an air cap, and a needle that opens and closes to control flow. Fluid nozzles wear from abrasive suspensions. Air caps clog with dried coating. Needles stick. All three parts are consumables.

Atomization air pressure controls droplet size. Higher pressure gives finer droplets. Lower pressure gives bigger ones. Wrong pressure for the formulation causes defects like orange peel, picking, or bridging on the tablet surface.

The spray arm positions all the guns at equal spacing across the tablet bed. On better machines, the arm adjusts automatically to keep the right distance as the bed level changes during the batch. Cheaper machines need manual adjustment, which is one more thing an operator can get wrong.

Pattern air widens or narrows the spray fan. Overlapping patterns between adjacent guns means some tablets get double-sprayed and others get missed. Setting up the pattern air right takes time but skipping it shows up in the finished product.

Tubing from the solution tank to each gun carries the coating liquid. Peristaltic pumps push the solution through. Pump tubing stretches and wears from the squeezing action. When it thins out, flow rate drops and coat weight comes in low.

3. Solution Preparation and Delivery System

Coating solution gets mixed in a jacketed tank before it goes to the guns. Tank has an agitator (propeller or paddle type) running at low speed to keep solids suspended without creating foam.

Jacketed tanks can be heated or cooled depending on the formulation. Some coating solutions need warming to stay at the right viscosity. Others foam if they get too warm. Temperature control on the jacket matters more than most people give it credit for.

A filter inline between the tank and the pumps catches lumps or undissolved particles that would clog the spray nozzles. Skipping the filter saves zero time and costs you a blocked gun mid-batch.

Scales or load cells under the tank track how much solution has been used. That gives you real-time coat weight data. Drifting load cells give wrong numbers and the batch ends up over- or under-coated.

Coating solution viscosity changes if the tank temperature drifts or if the agitator speed is off. Thick solution clogs nozzles. Thin solution drips and gives you uneven coverage. Check viscosity before you start spraying, not after the first defect shows up.

4. Air Handling Unit (AHU)

Hot, clean, dry air is what dries the coating on the tablets after it’s sprayed. AHU provides that air. Pulls it from the room, filters it, heats it, and sometimes strips humidity out of it before pushing it into the drum.

Pre-filters and HEPA filters clean the air. Pre-filters catch the big stuff. HEPA catches the rest. Clogged filters choke the airflow and batches take longer. In pharma, contaminated inlet air is a GMP violation nobody wants to deal with.

Steam coils or electric heaters bring the air up to temp. Steam coils are standard on production machines. Electric on lab-scale units. Leaking steam coil adds moisture to air that’s supposed to be dry. Drying performance tanks and nobody figures out why until maintenance pulls the coil apart.

Dehumidifier section gets added for humid climates or moisture-sensitive coatings. Without it, summer batches run slow because the inlet air already has moisture in it. Dampers control airflow volume. Stuck damper means too much or too little air going through, and both cause different problems.

5. Inlet and Exhaust Ductwork

Ductwork routes air from the AHU into the drum and pulls wet air out the other side. Stainless steel, sealed joints, insulated where needed.

Inlet duct feeds into the plenum behind the perforated drum. Air distribution panels or baffles inside the plenum spread the air across the full width of the drum so one end doesn’t get more drying than the other.

Exhaust duct pulls moisture-laden air out of the drum and through a filter before it exits the building. Exhaust filters catch any fine coating particles that got picked up by the airflow. Clogged exhaust filters restrict airflow and drying slows down.

Leaky joints in either duct cause problems. Inlet leak pulls dirty plant air into the system. Exhaust leak lets coating dust into the production room. Duct connections use clamps and gaskets that dry out and crack from heat. Check them during changeovers.

Insulation on the inlet duct keeps heat loss down. Damaged insulation means the air arrives at the drum cooler than the setpoint and the heater has to work harder. Also a burn hazard for anyone reaching past the duct during maintenance.

Flexible duct connections at the machine interface absorb vibration from the drum motor. These flex joints crack from heat cycling and movement. When they split, you get air leaks right at the machine that are hard to see but easy to feel if you hold your hand near the joint.

6. Exhaust and Inlet Blowers

Two fans run the airflow. Inlet blower pushes air through the AHU and into the drum. Exhaust blower pulls it out.

Balance between the two determines pressure inside the drum. Slightly negative pressure keeps dust from leaking out. Too much negative pressure collapses the tablet bed against the drum wall. Getting that balance right matters, and it shifts as filters load up during the batch.

VFDs on both motors let operators adjust air volume. Blower bearings wear. Motors overheat if filters clog and backpressure builds. Fan blades pick up coating residue and throw off balance.

7. Control Panel, PLC, and HMI

PLC runs the whole process. Drum speed, inlet air temp, exhaust temp, spray rate, atomization pressure, pan pressure. All automated and logged.

HMI touchscreen is where operators set up recipes, monitor the batch, and make adjustments. Screens take abuse from coated gloves, cleaning sprays, and daily use. Older machines have membrane keypads that wear out. Newer ones use industrial touchscreens behind glass.

Sensors feed data to the PLC. RTDs in the inlet and exhaust ducts. Pressure sensors in the drum and across the filters. Bad sensor means bad data. PLC makes wrong decisions based on wrong numbers and the batch suffers.

Recipe storage lets you save and recall settings for each product. When someone accidentally overwrites a recipe, every batch of that product runs wrong until somebody catches it. Lock your recipes.

In pharma, the whole system gets validated. IQ, OQ, PQ. 21 CFR Part 11 compliance for electronic records. Calibration schedules for every sensor. Audit trails that can’t be tampered with.

Alarm settings on the PLC catch process deviations in real time. Inlet temp too high, exhaust temp too low, drum pressure out of range.

Set alarms too loose and problems slip through. Set them too tight and the machine stops every five minutes. Operators start ignoring alarms altogether when that happens. Finding the right window takes experience with each product.

8. Guide Plates and Discharge System

Guide plates sit inside the drum opening and direct the flow of tablets during loading and unloading. They keep tablets from falling out the front while the drum is spinning.

Discharge chutes or conveyors move coated tablets out of the drum and into bins or downstream equipment. Chutes wear from tablet contact and get buildup from coating residue.

Loading can be manual or automated. Vacuum transfer or gravity feed from the tablet press are common on automated lines. Tablet breakage during loading usually comes from too much drop height or too fast a feed rate.

On the discharge side, door actuators open and close on PLC command. Door seals wear out, and leaky doors throw off drum pressure during the batch. Replace the seals before they get bad enough to affect coating quality.

9. Cleaning System (CIP/WIP)

Wash-in-place or clean-in-place systems spray water and cleaning solution inside the drum, over the spray arm, and through the ductwork without disassembly.

Spray balls or orbital cleaners inside the drum hit every surface. Cleaning solution drains out the bottom. When spray balls clog or lose pressure, cleaning coverage drops and residue stays behind. Failed cleaning verification means the batch can’t start.

Drain valves at the bottom of the drum need to seal properly during coating but open fully during cleaning. A valve that doesn’t open all the way leaves standing water and residue in the drum.

Some machines have automated CIP cycles programmed into the PLC with valve sequences, rinse times, and drain steps all logged. Manual cleaning is still common on older or smaller machines. Either way, the spray arm collects dried coating in spots that are hard to reach. Give it extra attention.

Conclusion

That’s the tablet coating machine parts name list from the drum all the way through the air system, spray guns, and controls. Perforated pan coaters have a lot going on. Every part plays into how the finished tablet looks, performs, and holds up on the shelf.

Spray nozzles, pump tubing, filters, and door gaskets wear fastest. Keep those stocked.

When coating defects show up that you can’t explain from the recipe, look at the hardware. Worn nozzle, stuck damper, clogged filter. Answer is usually mechanical.

Document your part numbers somewhere accessible. Coating machines have dozens of consumable parts from multiple vendors. Having that list ready saves hours of scrambling when something fails at 6 AM on a Monday.