Tablet Compression Machine (also referred to as Tablet press machine, tablet making machine, tablet machine, or tablet punching machine) is a mechanical device that is used to compress the granules or mixture of API and excipients to uniform and predetermined size, shape, and weight of tablets for research, pilot-scale, and full production. You may also read: Evaluation of tablets, Friability test of tablets, Tablet defects, Tablet coating defects.
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Types of Tablet Compression Machine
Based on punch number, tablet press machine can be classified into:
A. Single punch Tablet Compression Machine /Single station/Eccentric tablet press machine
Single punch tablet press machine is the simplest machine that uses a pair of punches (upper and lower) and a die to compress granules/powder mixture to make tablets for research and small-scale production.
B. Multi punches Tablet Compression Machine/ Multi-station/ Rotary presses
Multi-station press is a mechanical device that unlike the single punch tablet press has several stations which rotate to compress granules/powder mixture to a uniform size, shape, and weight of tablets with high productivity in a short time. It was developed to raise the productivity of tablets.
Common name of tablet compression machine manufacturers
Tablet compression machine parts
Core functional parts of the rotary tablet press machine are:
The hopper holds and supplies the granules/powder mixture (API and excipient) to the feeder system. It is the input point of powder mix or granules to tablet press for compression of tablets. Granules or powder mix may feed manually or using automated systems.
Feeder System or Feed Frame
Feeder System: Feeder System helps to force the feed of the granules into the die cavity, especially during faster rotation. It also mixes the granules and inhibits the separation of granules. Feeder System is also called a force feeder.
Force feeder of the tablet compression machine contains two vital parts:
- Feed Peddles: It rotates continuously and ensures consistent and accurate granules feed into the die cavity in a high-speed machine.
- Feeder Housing: Through the feeder housing, granules for tablets from the hopper will enter into the die system.
Some tablet press machines have a feed frame rather than Feeder System (Feeder Housing and Feed Peddles). The feed frame delivers the granules /powder mix into the die cavity under the influence of gravity. Tablet scraper and excess granules stripper must attach to the feeder system or feed frame.
Excess granules stripper
This part of the tablet press machine takes away extra granules from the surface of the die bore or cavity. The granules stripper is liable for controlling the volume of granules and ultimately the weight of tablets.
Die defines the size and shape of the tablet. Powder mix or granules are compressed into the desired size, diameter, and shape of tablets in die bore or die cavity.
Two punches (upper and lower) compress the granules/powder mix in the die bore. The lower punch moves upward and the upper punch moves downward and compresses the tablet within the die cavity. Then the upper punch moves upward and the lower punch moves upward.
Turret hosts the die as well as upper and lower punches on its holes and ensures the position of the die bore and two punches (lower and upper) for the tablet compression process. The turret is the heart-like part of the tablet press machine.
Cam track guides the movement of both the upper and lower punches in the tablet compression process that play an integral role in ensuring a smooth tableting process. As the turret rotates, the cam track helps to move the punches in up and down motion.
Tablet press machines have rollers that exert a predetermined and sufficient amount of force to compress the granules into tablets with desired hardness. Most tablet press machines have two sets of compression rollers.
Pre-compression roller: They give the initial compression force. The aim of pre-compression is to eliminate air that could be in the die or granules/powder mix.
Main compression roller: It exerts sufficient compression force to compress the granules into tablets. The rollers stay stable with no vibration during the entire compression process to ensure consistent thickness and size of the tablets.
Ejection cam guides the lower punch upwards assisting the ejection of tablets from the die bore or cavity after compression. The ejection cams slowly and gradually push the lower punch upwards.
Take-off Blade/Tablet Scraper
This is fitted in front of the feed frame or feeder system and scrap the compressed tablet to the discharge chute. The tablet scraper (also known as takeoff scraper or tablet take-off) pushes the compressed tablets away from the die table of the compressing machine to the discharge chute.
Guides the compressed tablets to a collection drum or bin.
Tablet Weight Controller
This is used to adjust the volume of the granules to be compressed and so determines the weight of the tablet with the help of different movements of the cam systems, material will flow into the die cavity depending on the position of the punches.
Other Tablet Compression Machine Parts
- Safety System
- Touch Screen display and control panel
- Belts, Gears, Electric Motors
- Lubrications Systems
- Hydraulic Pump System
Applications of Tablet Compression Machine
- The key application of the Tablet Compression Machine is used to compress the granules or mixture of API and excipients to uniform and predetermined size, shape, and weight of tablets for new tablet development and small batch production.
- Compress the granules/ powder mix into tablets for pilot-scale and full-scale production.
- To compact the blend of powder in the dry granulation method. Compression vs Compaction
- To compress multi-layer tablets such as bi-layer, tri-layer, four-layer, and five-layer tablets.
Advantages of Single Punch tablet compression machine
- Rational and small.
- Easy to operate.
- Easy to clean.
- Ideal for new tablet development and small-batch production.
- Due to single a set of punches, less chance of weight variation.
- Less noise production.
- Minimal spare part requirements.
- Operate by both motor and manually.
Advantages of Multi-station/Rotary presses
- High-speed operation.
- Robust design and high productivity.
- High overall equipment effectiveness.
- Minimal product loss.
- Low noise level in operation.
- Compact machine with space-saving design.
- Ease washable and high containment technology.
- High safety system.
- Modern Rotary presses may control digitally.
- Optimized lubrication system.
Cleaning and maintenance of Tablet Press or tablet compression machine
- After an operation, Turn off the electric supply.
- Dismantle all the common jointed parts such as the guard, hopper, and feed frame/ feeder system.
- Remove powder dust and wasted granules with the vacuum cleaner.
- Dismantle all punches and punches and die.
- Clean all surfaces of the tablet press machine with a dry lint-free soft cloth and then by using compressed airflow.
- Wipe out the surfaces of the tablet press machine and its functional parts with 70% v/v Isopropyl Alcohol.
- Clean the hopper, feed frame/ feeder system, and other accessories with potable water and rinse with purified water
Maintenance (Lubrication and Storage) of Tablet press machine
Lubrication is done by using H1 lubricants like castor oil or liquid paraffin, but there is a problem with the rancidity of the oil. Thus nowadays several synthetic liquid lubricants and solid or semisolid lubricants (grease) are available such as
- ET- 10S, ET- 20S, ET- 90S, ET- 140S Lubricants oil
- ET- 2S grease
- HT-1000G Lubricating Grease
Differences between single punch tablet press and rotary tablet press
- The vital functional difference between a single punch tablet press and a rotary tablet press is Single punch tablet presses have 2 punches but utilize only the upper punch for compression of granules to make tablets. On the other hand, rotary presses may have multiple punches and utilize both upper and lower punches.
- The setting and operation of a Single press are very simple while the operation of a rotary tablet press is complex.
- The productivity of a Single press is less whereas the Productivity of a rotary tablet press is more.
- A single-punch tablet press is suitable for small-scale production and research and development of tablet formulation. On the other hand, the rotary tablet press is suitable for research and development, scale-up, and large-scale production.
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