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The Different Types Of Tablet Press

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14 June 2016 No comments

Tablet machines, also called as compressing machines or tablet presses, are the equipment used to compress the powder into its tablet form forming uniform size, shape and weight. The compressing machine may also be used for manufacturing of other tablets such as for cosmetics, cleaning products and pharmaceutical drugs.

Definition

Powders containing the drug formulation and excipients are compressed together by stamping machines called presses. These presses may also sometimes be called as compression machines or tablet presses. The powdered form of the drug is metered into a cavity that is formed with two punches and a die. The punches presses together to fuse together the materials and form the solid tablet form.

Basic Components of Tableting Machine

  • Hopper – this holds the materials that are to be compresses
  • Dies – it defines or molds the size and shape of the powder
  • Punches – the punches compresses the materials within the die
  • Cam track – this helps or guides the punches’ movement
  • Feeding mechanism – it moves the materials from the hopper to the die

Tableting Machine Types

  • single station - may also be called single punch or eccentric presses
    Simplest of all machine type. It uses a single tooling station that has a die and a pair of upper and lower punch
    Manual or power operated
    The compression force is exerted by the upper punch whereas the lower punch stays immovable
    The instrument used in the press is the compaction of the powder that happens when pressure is exerted through the upper and lower punch. The resulting tablet is then formed in the die cavity. Compression involves only the upper punch.
  • multiple station – or rotary presses
    The machine head holds the die and the upper and lower punches where the lower punch are in the rotary motion.
    As the head of the machine rotate, the punches moves up and down the track. The fixed cam track controls the compression, filling and the ejection process.
    Part of the head that holds the upper and lower punch is also called as the upper and lower turrets. The portion that holds the die on the other hand is called the die table.

Tableting Machine Tooling

The compression machine tooling determines the shape, identification marking as well as the size of the tablet. Each of the tooling set includes upper and lower punch as well as dies. As many of the tablets are formed by these equipment, the latter must meet several guidelines in order to produce uniformity in terms of dosage, aesthetic appearance as well as production efficiency.

  • D-tooling
    Barrel diameter-1 inch
    Dies outer diameter-0.945
    Length-5.25 inch
    Head Diameter-1 and 1/4 inch
  • BB Tooling
    Barrel diameter-0.75 inch
    Dies outer diameter-30.16 mm
    Length-5.25 inch
    Head Diameter-1 inch

Difference between B&BB and D&B tooling

The B tooling is the same as the BB tooling with the only difference is in the length of the lower punch which is 3 and 9/16 inch long.

The D tooling dies and punches has thick diameter as well as with regards to the punches tip. Dies also has bigger outer diameter as compared to the B type tooling.

Depending on the product’s requirement, dies and punches of different sizes are manufactured.

How Tableting machine works?

Single Station

Filling

The upper punch is withdrawn from the die by the upper cam, the bottom punch then is lowered to the die to the powder would fall through the hole and fill the die. The bottom punch would then move up to adjust the weight and then raises to expel the powder.

Compression

The upper punch is driven into the die by the upper cam, the bottom punch is then raised by the lower cam. Both punches would then move together in between heavy rollers to compress the tablet.

Ejection

The upper punch is withdrawn by the upper cam while the lower punch is pushed upward to expel the tablet. The tablet is then removed from the die surface by the surface plate.

Multiple Station

The material to be punched is place to the hopper and emptied to the feed frame which is interconnected with other compartments

The compartments spread the materials to different areas allowing the die to be filled up

The pull down cam guides the lower punches to the bottom area which allows the dies to be overfilled

The punch will then pass through weight control where excess fills are removed

A swipe off blade is used to remove the excess material while at the same time guide the material towards the turret and back into the front area of the feed frame

The lower punch on the other hand also travels simultaneously with the upper punch to the upper compression roll

The upper punch will then enter a fixed distance to the die whereas the lower punch is raised to squeeze and compact the powder insider the die

During the compression stage, the upper punch is withdrawn followed by the upper raising cam

The lower punch then rides the cam where it brings the tablets above the dies surface

The tablet is then sweep off from the feed frame towards the chute and into a receptacle

The lower punch will then re-enter the pull down cam and start over again

Advantages of Tablet Machines

Single Station

  • The structure is small
  • Easy to operate and has high utilization ratio
  • Uses high pressure to reduce weight difference between tablets while maintaining a low noise level
  • Provides continuous control over raw material loading as well as tablet’s thickness
  • Each function available is also comparable to expensive and imported machinery

Multiple Station

  • Independent control of hardness and weight
  • Reduction of trial and error manual operation adjustment
  • Can be fine tune to meet all specification
  • Reduction of waste of formulation
  • Pressure is controlled by adjusting the lever
  • Automatic powder filled cavity
  • Supplied without punches or dies
  • Output: 9000 - 12000 tab/hr.
  • Cost efficient and time saver

Industrial Application

Tablet presses are essentials in the pharmaceutical world. Tablet presses must allow the operator to adjust the lower and upper punches to control accurately the tablets weight, density and thickness. This is achieved by using rollers, cams and other trackers that can also act as tablet tooling. The mechanical system are also incorporated for ejecting, filling and removal of the tablet after compression. The pharmaceutical tablet presses are required to be cleaned and configured quickly than other tooling set as they can be used for a variety of products.

Single Punch Tablet Machines

These machines are used to press a variety of drug that may or may not contain excipients to round tablet. It can also be used for batch production or lab.

Can be manually operated

One pair of the die may be use during the pressing so that the filling depth and thickness of the tablet is adjustable.

Example: The required amount of the fill is weigh and then compressed with a single punch machine.

Chewable – examples - mannitol, lubricants and other ingredient binders.

Effervescent – examples – tartaric, sodium bicarbonate or citric acid.

Compressed – examples – disintegrants, lubricants, active drug, and diluents.

Rotary Tablet Pressing Machine

This machine is used in the industrial, medical and pharmaceutical industry

More cost efficient

Can work continuously without any increase in maintenance expenses

Best machine to use to manufacture tablets due to its efficiency and accuracy in producing uniform shapes and sizes of tablets

Preferred by many in the industry due to its high output

The machine can be used for all types of active agents

Example: compressed, chewable, sugar pieces, effervescent, calcium tablets