Tablets & Capsules

TC0917

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22 September 2017 Tablets & Capsules With internal cap fixing, punch tips are inserted into the cap, which is then secured to the punch body with self-locking screws. Residue will naturally stick to the exposed composite parts but can be easily cleaned off. To manage contamination risks, simply strip the tool and clean each component part. External cap fixing resembles internal cap fixing, but because fixing pins secure the cap by traversing the punch and cap, it can accommodate more tips per punch. As with internal cap fixing, strip and clean the compo- nents if contamination is a concern. To ensure the punch guides and seals won't be compromised and the fixing hole won't interfere, consult a tooling designer. The pin fixing configuration does not have a cap. Instead, individual tips are inserted into the punch body and secured with fixing pins. This assembly reduces the risk of contamination and requires fewer components than the internal cap and external cap assemblies, which simplifies punch tip replacement.Component cleaning is the same as mentioned above. A sealant can be applied to the pin holes if required. Monoblock multi-tip punches are ideal when using a press equipped with a wash-in-place system. Unlike the other three configurations, a monoblock punch doesn't require disassembly because it is machined from a single piece of steel. The absence of joints also minimizes the potential for contamination and eliminates the risk of damage to punch guides or seals. If the tip of a monoblock is damaged, however, the whole punch must be replaced. As with standard punches—and the other multi-tip punches—monoblocks can include seal grooves that accept drip cups, which protect tablets from machine lubricants and other contaminants during compression. However, this reduces the number of tips per punch compared to the other multi-tip punch configurations. To demonstrate how a multi-tip monoblock can improve production rates and increase output, we com- pared the performance of single-tip to two-tip monoblock tooling on a Fette tablet press equipped with a segmented die table. With the single-tip tooling, the press ran at 900 rpm and produced 900,000 tablets per hour. But the customer required more output, so we installed the two-tip monoblock tooling and ran the machine at 1,200 rpm, which increased the output to 2.4 million tablets per hour. EDM versus milling There are two methods to create monoblocks: Electro- discharge machining (EDM) and milling. EDM is a man- ufacturing process that uses electrical discharges to remove material and shape the punch. Milling uses rotary cutters and computer numerical control machines to remove material. A 2002 study compared how EDM and milling affected the fatigue life of tool steel [1]. Researchers used various tests to characterize the tool steel's surface roughness, Monoblocks are shaped from a single piece of steel and require no assembly or disassembly. Two-tip punches in the four common assembly types Internal cap fixing has self-locking screws that create a tight joint between cap and punch body, and thus reduce risk of contamination. External cap fixing can accommodate more tips per punch than internal cap fixings because of the position of the fixing pin. Pin fixing has fewer components than internal and external cap fixing assemblies, which speeds tip replacement and reduces the risk of cross-contamination. Monoblock Pin fixing Internal cap fixing External cap fixing Punch body Anti-turn key Fixing pin Cap Individual tips External cap fixing Internal cap fixing Fixing screws Individual tips Punch body Anti-turn key Monoblock Wash-in-place key Anti-turn key Fixing pins Punch body Individual tips Pin fixing

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