Objective:
The purpose of this standard Operating Procedure (SOP) is to lay down a procedure for handling and control of punches and dies, used during compression.
Scope:
This procedure is applicable for procurement, usage, cleaning, maintenance and disposal of all the punch sets (i.e. new and in use) and related testing kits, i.e. punch height checking kit and punch polishing kit used in Tablet department at manufacturing facility of Pharmaceutical Industry.
Procedure:
ORDERING NEW PUNCHES AND DIES:
ORDERING OF NEW SET OF PUNCHES AND DIES OR ORDERING OF EXISTING PUNCH SET WITH NEW PARTY.
Drawing’ for Upper punch, Lower punch and Die should be prepared by the manufacturer as per the specifications given or as per sample punch set.
After primary approval of the drawing, sample punch set (1Upper punch, 1 lower punch and 1 die) will be received from the supplier.
Department Head will approve ‘Sample punch set’ after taking a trial on the machine.
Standard specification of punch set for respective product is prepared after successful trial and approval of sample write down in appropriate Annexure.
After approval of the ‘Sample punch set’, Purchase order for the full set of punches and dies will be initiated by the Purchase Department Head, and authorized by the Unit Head, giving following details:-
The total number of punches and dies required for Compression machine will be as follows.
Example :- For 26 station m/c: 31 sets, For 32 station m/c: 37 sets, For 55 station m/c: 60 sets
Type of Tooling required e.g. D/B type.
Material of construction to be used (High Carbon High Chromium (HCHC) /Oil Hardened Not Shrinkable (OHNS)).
Engraving/laser etching of following details on individual punch
Serial number.
Name of the manufacturer (Short form) e.g. GMI for General Mechanical Industries.
Date of Manufacturing (Month and Year).
Punch size in millimeter.
Any other Specifications/Special requirements like embossing, central break line, beveled edge, chrome plating, groove on upper punches for rubber cups etc.
After receiving the consignment, punches and dies will be checked as per standard specification / sample punch set of respective punch set. Along with the following additional checks:-
Appearance (finishing of Punch set)
Damages (cracks/chips)
Height of punches (Working length)
Proper fitting of punches and dies on the machine
Record the observations in the appropriate Annexure
Supplier should provide following documents with punch set :-
Drawing
Certificate of material of construction
Inspection report
ORDERING OF EXISTING PUNCH SET FROM SAME SUPPLIER:
Place the order to the manufacturer who had supplied earlier punch set for the particular product.
Give one set to the manufacturer as a sample and repeat the step no. as above mentioned.
CHECKING OF PUNCHES AND DIES:
Each punch and die should be checked individually using the standard specification.
Check the details engraved on individual punch and die as above mentioned.
For new punch set if supplier has provided all test documents then it should be taken for use after verification and QA approval based on in-house verification.
Checks for Punches:
Tip Dimension. Check individually UP and LP by vernier calliper.
Tip surface Check visually for scratches, damages, surface finish, cracks, pits, and spots and chrome plating (if applicable).
Body surface Check visually for scratches, damages, surface finish, cracks, pits, spot and chrome plating (if applicable)
Chamfer Check visually for angle, uniformity
Tips edge: Check visually for damages, cracks, sharpness and burr
Embossing
Check visually for letters, flattening of letters, burr, roughness, cracks and deep score.
Central Break Line
Check visually for position, flattening, roughness, cracks, deep score
Checks for Punches:
Inner dimensions- Inner dimension of bore with help of vernier calliper and by inserting lower punch in it. Inner surface, Check visually for scratches, damages, surface finish, cracks, pits, spots and chrome plating (if applicable).Body surface, Check visually for surface finish, level uniformity, edges (both upper and lower surfaces)
NOTE: Check individual die by inserting upper and lower punch in it and check for its freeness
Frequency Of Checking
The Punch Set When the punch set is new, Quality Assurance should certify the punch set. (Annexure V). Visual checking of Punch set should be done after every batch and at the time of fixing or removing the punch set from machine.
PUNCH HEIGHT CHECKING:
Take the punch set from the punch set cabinet.
Clean all the upper and lower punches as per SOP and arrange them in sequence with the help of their serial numbers.
Assemble the punch height variation checking equipment.
Clean the platform of punch height checking equipment.
Place the Calibrated Standard Hobb (supplied along with equipment) on platform and adjust it below the dial knob.
Set dial indicator to ‘zero’ by rotating the dial of equipment. Recheck the ‘zero’ setting of dial indicator with standard Hob and check the height of punches as per following instructions.
Check the ‘Variation Working Length’ for deciding the suitability of the punch In all types of punches viz. Concave, Flat Beveled Edge etc.
Keep the punch in ‘Head DOWN and Tip UP’ position while checking the punch height i.e. Critical Working Length and find out the constant minimum reading on the dial by moving the tip-surface of punch against the pointer (actuator) of the dial gauge.
Check and record the variation in height of all punches in Annexure I Discard the punch if the difference is more than + 0.003 inch (in case of round shaped) and +0.005 inch (in case of other than round shaped than the standard height 133.600 mm).
Clean the platform and dismantle the equipment. Keep the equipment parts, dial and standard punch in the respective drawer.
Frequency of punch height checking is as per following table.
Punch set type | Punch set life | Height-checking frequency |
Circular | 4 million tabs/set | 2 million tabs/set |
Other than circular | 2 million tabs/set | 1 million tabs/set |
Double layered (circular) | 2 million tabs/set | 1 million tabs/set |
Double layered (noncircular) | 1 million tabs/set | 0.5 million tabs/set |
1 set = 1 upper punch + 1 lower punch + 1 die
NOTE:
Punch height shall be checked as per height checking frequency or one year, whichever is earlier.
Always consider the minimum reading on the dial indicator, which shows the deepest point on the punch tip surface.
In case of embossed punch tip with break line the reading should be taken by adjusting the pointer on plain surface at the same location on each punch.
POLISHING OF PUNCHES AND DIES:
PUNCH SHOULD BE POLISHED WHEN.
There is burr or claw on punch tip.
Punch tip turns black.
Roughness on the tip is observed.
Sticking/picking problem is observed.
Appearance of tablet becomes dull.
DIE SHOULD BE POLISHED WHEN.
There is ring formation inside the die-bore.
Die-bore surface becomes black.
Corrosion is observed inside die-bore.
Wear or drag is observed in die-bore
POLISHING OF PUNCHES AND DIES.
Tooling type | Polishing tool | Polishing material |
Punches | Nylon brushes | Emery paste |
Dies | Felt bob | Emery paste |
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