Basics of Tablet Tooling
Tablet compression machines are made keeping in view the type of dies and punches will be used on them. The dies and punches and their setup on compression machine is called tooling, it is classified as B and D mainly.
The B tooling dies and punch can further have specifications as BB and D tooling can also be dies and punches can be utilized on B tooling machine which is called as DB.
Mainly there are two standards, D and B, in US specification provided by Tableting Specification Manual (TSM) is followed where as in Europe European standard known as the EU, or “Euronorm” standard. There is not much difference in both the specifications but both are very different.
1. Head: The end of the punch that guides it through the cam track of tablet machine during Rotation.
2. Head flat (Dwell Flat): The flat area of the head that receives the compression force from Rollers (in upper punches) and determines the weight and ejection height (in lower punches).
3. Outside head Angle: The area gets in touch with the roller prior to head flat , while Compression.
4. Inside Head Angle: This is the area, which pulls down the lower punches after ejection and lifts the upper punches after compression.
5. Neck: The relived area between the head and barrel, which provides clearance for the cams.
6. Barrel: This area guides the punch (while going up and down) with reference to turret guides.
7. Stem: The area of the punch opposite the head, beginning at the tip and extending to the point where the full diameter of the barrel begins. If the chamfer is present the barrel usually reaches its full diameter just above the chamfer.
8. Tip: This determines size, shape & profile
9. Tip face: This area of punch is where the tablet is formed. Good surface finish is required here to get quality tablets.
10. Working length: This distance between bottom of the cup and the head flat is called as working length which determines weight and thickness of the tablet.
11. Overall length: Distance between top of the cup and the head flat.
12. Key Angle: The relationship of the punch key to the tablet shape. The keys position is influenced by the tablet shape, take-off angle, and turret rotation.
13. Domed Heads: Increases the dwell time and hence help to achieve the better tablet hardness.
14. Dwell time – The time punches spends below the pressure roller while rotating in the machine.
15. Clearance: Die bore dia – punch tip dia = Clearance.
16. Hardness: Usually measured in HRC (Rockwell ‘C’ scale) and optimum readings are as follows:
It is a hardened steel (HCHC) mould to make the shape of a tablet.
1. Die O.D.: The outside diameter of the die, which is compatible with the die pockets in the press.
2. Die Height: The overall height of the die.
3. Die Bore: The cavity where the tablet is made. The Cavity’s shape and size determine the same form of tablet.
4. Chamfer: Entry angle of the die bore.
5. Taper dies: dies with tapered bore on one or both sides. They are used for easy ejection of tablets (mainly for double layered tablets.
6. Die Groove: The groove around the periphery of the die, which allows the die to be fixed in the press.
7. Lined (Insert) Dies: Dies fitted with a linear insert made from a much harder, more wear resistant material such as tungsten carbide and ceramic.
There are following types of tooling available:
• ‘B’ -Tooling
• ‘D’ – Tooling
• ‘BB’ -Tooling
• ‘DB’ – Tooling
Tip diameter of punches:
Check the tip diameter with the help of a Vernier caliper. Check and set the zero reading of the Vernier caliper. Place the punch tip in a vertical position. Check the fine setting of the Vernier caliper and record the reading. The readings should be within ± 0.1 mm of the standard dimension.
Difference in height of the punches:
Set the dial gauge of the inspection kit at zero position with the help of the standard punch height 133.60 mm. Keep the punches one by one inside the punch holder over the metal pad of the inspection kit and check the difference in deflection from the zero position.
The difference should not be more than ±0.08 mm of the standard dimension.
Body diameter of punches:
Check the body diameter with the help of a Vernier caliper. Check and set the zero reading of the Vernier caliper. Check the fine setting of the Vernier caliper and record the reading. The standard dimensions and limit are as in table.
Embossing of punches:
Visually check the embossing and record the observation.
Difference in concentricity of punches:
Keep the punch over a ‘V’ block pad horizontally by keeping the magnet on and set the dial gauge at zero position over the punch body. Rotate the punch in the clockwise direction, take two readings each from the punch (one from the top and one from the bottom of the punch body) and record the observations.
The deflection should be within ± 0.05 mm of the standard dimension. Keep the punch over a ‘V’ block pad horizontally by keeping the magnet ON and set the dial gauge at zero position over the highest point on tip
diameter. Rotate the punch in the clockwise direction and record the observations. The deflection should be within ± 0.025 mm of the standard dimension.
Go and No-Go of punch head:
Take “B” or “D” type tooling “Go-No Go” punch head tester for checking punch head.
Move the punch head through “go” side of punch head tester it should pass easily. Move the punch head through “no go” side of punch head tester & it should not pass through it.
Outer diameter of dies:
Set the dial gauge of the inspection kit at zero position with the help of the standard die master piece. Keep the dies horizontal position one by one over the metal pad (V BLOCK) of the inspection kit and check the outer dimension deflection from the zero position. Record the reading.
Height of the die:
Set the dial gauge of the inspection kit at zero position with the help of the standard die master piece. Place the dies in vertical position one by one over the metal pad of the inspection kit and check the height deflection from the zero position. Record the reading.
Difference in concentricity of dies:
Keep the die over a ‘V’ block in horizontal position and set the dial gauge at zero position over the die body. Rotate the die in the clockwise direction, take two readings each from the die (both side) and record the observations. The deflection should be within ± 0.05 mm.
Inspection of punches and dies to be done after receiving of a new punch set and after compression of two million tablets per subset.
Referances: A Text Book of IINDUSTRIIAL PHARMACY — II [FORMULATIVE PHARMACY] by Dr. B. Prakash Rao,S. Rajarajan,Dr. Beny Baby
Mr. Shiv Kumar is the Author and founder of pharmaceutical guidance, he is a pharmaceutical Professional from India having more than 14 years of rich experience in pharmaceutical field.
During his career, he work in quality assurance department with multinational company’s i.e Zydus Cadila Ltd, Unichem Laboratories Ltd, Indoco remedies Ltd, Panacea Biotec Ltd, Nectar life Science Ltd. During his experience, he face may regulatory Audit i.e. USFDA, MHRA, ANVISA, MCC, TGA, EU –GMP, WHO –Geneva, ISO 9001-2008 and many ROW Regularities Audit i.e.Uganda,Kenya, Tanzania, Zimbabwe. He is currently leading a regulatory pharmaceutical company as a head Quality. You can join him by Email, Facebook, Google+, Twitter and YouTube