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Tablet Press/ Tableting machine / Tablet Compressing machines

Pharmaceutical Tablet Press or Tableting machine or Tablet Compressing machines

Tableting Machine is the device that compresses the powder into tablet of uniform size with different shape and uniform weight and also called as compressing machine or tablet press / machine. A Tablet compressing machine can be used to manufacture tablets of a wide variety of materials, including pharmaceuticals, illicit drugs, cleaning products, and cosmetics.

Tableting machines are used commonly in pharmaceutical industry. Millions of tablets can be pressed but using this machines/presses.

What is the definition of tablet press/machine?

Tablets are prepared or made by compressing a formulation containing a drug or the drug with excipients on stamping machines called presses. So it is also called as compression machine or tablet presses. To form a tablet, the formulation containing a drug or the drug with excipients material must be metered into a cavity formed by two punches and a die, and then the punches must be pressed together with great force to fuse the material together.

What are the components of the tableting machine?

Tablet compression machine/tablet presses are designed with the following basic components:

Hopper: It is used to hold the materials (drug or the drug with excipients/ granules) to be compressed.

Dies: Dies defines the shape and the size of the tablet.

Punches: These are used for compressing of the materials (drug or the drug with excipients/ granules) within the dies.

Cam track: This is the component used for guiding the movement of the punches.

Feeding mechanism: A feeding mechanism for moving the materials (drug or the drug with excipients/ granules) from hopper into the dies.

What are the types or classification of tableting machine?

Tablet machines can be divided into two types:

  1. Those with the single set of tooling - single station /single punch/eccentric presses

  2. Those with the several stations of tooling - multiple station/rotary presses

Single station /single punch/eccentric presses:

  • It is the simplest machine for manufacturing of tablets. Single station press employs a single tooling station that is a die and a pair of lower and upper punch. This press can be available as both manually operated or power driven.

  • In this press the compression force on the fill material is exerted by only the upper punch while the lower punch is immovable such as action equivalent to hammer motion.

  • The mechanism involved in this press is that the compaction of the powder blend is by exerting the pressure through upper and lower punches. Then the resultant tablets are formed in the die cavity with their size and shape. It involves compression of only the upper punch.

Tabletting Machine

a) Single station /single punch/eccentric presses b) Upper and bottom punch with die

Multiple station/rotary presses:

  • In this multiple station/rotary presses the head of the machine holds the upper punches, dies and lower punches. Lower punches are in the rotary motion.

  • As the head rotates the punches are moved up and down by fixed cam tracks, which controls the filling, compression and ejection processes.

  • The portions of the head that holds upper and lower punches are called as upper and lower turrets. The portion holding the dies is called as die table

Old  and New multiple station and rotary press

  1. Old multiple station/rotary press b) New multiple station/rotary press

What are the tableting machine toolings?

The shape, size and the identification markings of the tablets are determined by the compression machine tooling.

Each tooling set includes dies, upper and lower punches. Since many tablets are formed by a tooling set, the tooling must meet the specific requirements to satisfy the needs of dosage uniformity, production efficiency and esthetic appearance. Most commonly used toolings are BB tooling and D tooling.

D tooling:

Barrel diameter-1 inch,

Head Diameter-1 and 1/4 th inch,

Length-5.25 inch ,

Dies outer diameter-0.945.

BB Tooling:

Barrel diameter-0.75 inch,

Head Diameter-1 inch,

Length-5.25 inch ,

Dies outer diameter-30.16 mm

What is the difference between B&BB tooling and D&B tooling?

B tooling

D tooling

B tooling is same as BB only difference is that lower punch length is just 3 and 9/16th inch long.

D tooling dies and punches are usually have thick diameter or have greater diameter of their body as well as the tip of punches also dies have greater outer diameter compared to B type tooling

Many sub categories like DB, BB type tablets dies and punches are made depending up on the punches and dies requirement of product.
Different types of dies, upper and lower punches used in single and multiple press

Different types of dies, upper and lower punches used in single and multiple press

How the tableting machines works?

A tablet is formed by the combined pressing action of two punches and a die.

Single station /single punch/eccentric presses:

FILLING:

Step-1: Upper punch is withdrawn from the die by the upper cam, bottom punch is low in the die so powder falls in through the hole and fill the die.

Stage-2: Bottom punch move ups to adjust the powder weight, it rasies and expelles the powder.

COMPRESSION:

Stage-3: Upper punch is driven into the die by upper cam. Bottom punch is rasied by lower cam. Both punch heads pass between the heavy rollers to compress the tablet.

EJECTION:

Stage-4: Upper punch is withdrawn by the upper cam. Lower punch is pushed up and expel the tablets. Tablet is romved from the die surface by the surface plate.

Stage-5: Return to the 1st stage.

Compression cycle of single punch

a & b) Compression cycle of single punch

Multiple station/rotary presses:

  • Material to be punched from hopper empty in the feed frame(A) containing several interconnected compartments.

  • These compartments spread the material over a wide area to provide time for the dies (B) to fill.

  • The pull down cam (C) guides the lower punches to the bottom, allowing the dies to overfill.

  • The punch passes over a weight-control cam (E), which reduces the fill in the dies to the desired amount.

  • A swipe off blade (D) at the end of the feed removes the excess material and direct it around the turret and back into the front of the feed frame.

  • The lower punches travel over the lower compression roll (F) while simultaneously the upper punches ride beneath the upper compression roll (G).

  • The upper punches enter a fixed distance into the dies, while the lower punches are raised to squeeze and compact the material within the dies.

  • After the moment of compression, the upper punches are withdrawn as they follow the upper punch raising cam (H).

  • The lower punches ride up the cam (I) which brings the tablets flush with or slightly above the surface above the surface of the dies.

  • The tablet strike a sweep off blade affixed to the front of the feed frame (A) and slide down a chute into a receptacle.

  • At the same time, the lower punches re-enter the pull down cam (C) and the cycle is repeated.

Compression cycle of multiple station/rotary press

a & b) Compression cycle of multiple station/rotary press

What are the advantages of tablet machines?

Single station /single punch/eccentric presses:

  • The machine structure is rational and small.

  • It is very easy to operate and it operates at high utilization ratio.

  • The machine utilize a high amount of pressure to reduce the weight difference between the tablets while maintaining a low noise level.

  • The machine also provides continuous control over the loading of the raw materials, and the thickness of tablet.

  • Each and every function of the machine can be compared favourably with the imported machines.

Multiple station/rotary press

  • Allows independent control of both weight and hardness.

  • Reduces trial-and-error operator adjustments for changes in powder characteristics.

  • Fine tunes processing to meet all tablet specifications.

  • Decreases waste of valuable formulation in non-specific tablets.

  • Pressure on the tablets is controlled by adjusting a lever

  • Powder filled in cavity is managed automatically by a moving feeder

  • Supplied without dies/punches

  • Output: 9000 - 12000 tab/hr.

  • Increase the production capacity while saving money and time saving.

What are the industrial applications of tablet machines?

The tablet press is an essential piece of machinery for any pharmaceutical and nutraceutical manufacturer. Tablet presses must allow the operator to adjust the position of the lower and upper punches accurately, so that the tablet weight, thickness and density can be controlled. This is achieved using a series of cams, rollers, and/or tracks that act on the tablet tooling (punches). Mechanical systems are also incorporated for die filling, and for ejecting and removing the tablets from the press after compression. Pharmaceutical tablet presses are required to be easy to clean and quick to reconfigure with different tooling, because they are usually used to manufacture many different products.

Single Punch Tablet Machines:

  • This machine is used for pressing different kinds of drug and drug containing different excipients into round tablets. It is used in lab or batch production.

  • It can be hand-operated.

  • One pair of punching die is used in this press, so filling depth of material (drug and drug containing different excipients) and thickness of tablet are adjustable.

Examples:

  1. Chewable tablets (Mannitol-sweet, cooling taste, other ingredients-binders (e.g., acacia), lubricants (e.g., stearic acid), colors, and flavors). The desired quantity of mixture is weighed and then pressed with a single-punch tablet machine.

  2. Effervescent tablets (tartaric acid, citric acid, and sodium bicarbonate). These powders are weighed and pressed into tablets using the same procedure as chewable tablets.

  3. Compressed tablets (active drug, a diluent (e.g., lactose), a disintegrant (e.g., starch), and a lubricant (e.g., 1% magnesium stearate)). Pressed into tablets using the same procedure as chewable tablets and Effervescent tablets.

Rotary Tablet Pressing Machines:

  • This is used medically, pharmaceutically and industrially.

  • This is less in cost.

  • These tablet pressing machines can work continuously without any high maintenance cost.

  • Rotary tablet press is the best machine used for the purpose of making safe and healthy tablets.

  • This is used for producing tablets of perfect sizes and shapes, accuracy and efficiency to manufacture the tablets.

  • This machines are widely chosen in industry to produce the tablets as per requirement.

  • That can make hundreds of thousands to millions of tablets an hour with much greater pressure.

  • All types of active agents can be pressed by this press.

Examples:

  1. Sugar pieces, calcium tablets, Chewable tablets, Effervescent tablets, compressed tablets etc can be pressed by this multiple/ rotary press.

References:

  1. Lieberman, Herbert A, Lachman, Leon (2009), Industrial pharmacy: Pharmaceutical dosage form-tablets. Banglore, Pune. ISBN:978-81-239-1679-8.

  2. http://wikipedia.org/wiki/single or rotary punches/tableting machines.

  3. http://alibaba.com/single or rotary punches/tableting machines.

  4. Gilbert S. Banker(2002), Modern Pharmaceutics: Pharmaceutical dosage form-tablets. 4th edition. New York. ISBN: 0-8247-0674-9.

  5. Ansel howard C, Allen V, Popovich G, Ansel's Pharmaceutical dosage form-tablet. 8th edition. ISBN: 0-7817-4612-4.

About the Author

Saraswathi.B's picture
Author: Saraswathi.B

Assistant Professor in St. johns college of pharmacy

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