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Photo 2: Coarse granules in the fill material can distort the capsule body, preventing smooth closing and causing cap tucks. 16 January 2019 Tablets & Capsules Photo 3: Be sure to check the alignment of the turret in relation to the closing station during machine setup to prevent damaged capsules. (Unit pictured is a Bosch 3005.) Capsule size Recommended fill weight At 0.6 g/ml At 0.8 g/ml At 1.0 g/ml At 1.2 g/ml 000 822 1,096 1,370 1,644 00E 612 816 1,020 1,224 00 570 760 950 1,140 0E 462 616 770 924 0 408 544 680 816 1 288 384 480 576 2 216 288 360 432 3 162 216 270 324 4 120 160 200 240 Table 2 Approximate recommended capsule fill weights at various powder bulk densities (in milligrams) Source: CapsCanada gelatin capsules technical data sheet 2018 will also need to re-establish the gap when switching between capsule suppliers, as each supplier's capsules have slightly different characteristics. Fill material The characteristics of the fill material can also cause cap tuck defects. Coarse granules with hard and sharp edges can distort and cut into the capsule body, prevent- ing smooth closing. Many capsule suppliers specify the maximum particle size for encapsulated powder to be 30 mesh (600 microns), but in a blend, you would not want more than a small percentage of particles to be that large. Filling capsule shells beyond their recommended capacity can also result in cap tucks. In some cases, slightly lowering the capsule fill weight will eliminate this problem. Take advantage of the elongated capsule sizes if overfilling is resulting in cap tucks. Approximate fill weights for various capsules sizes and powder bulk densi- ties are shown in Table 2. Quality of powder slug During capsule filling, the empty capsule body receives the powder in the form of a tamped slug, which often extends above the cut edge of the body, as shown in Figure 2a. This slug of powder must remain in a compacted cylindrical form during capsule closing. Poorly formed slugs (Figure 2b) will cause the weight of the filled capsules to vary and can also con- t r i b u t e t o c a p t u c k s . O n t a m p i n g - s t y l e f i l l i n g machines, ensure that the dosing disc you are using is the appropriate thickness. On dosator-type filling equipment, proper compression will help with slug for- mation. In some cases, using smaller dosing tooling (size 1 tooling for a size 0 capsule, for example) can create a narrower slug, which may eliminate defects. Condition of filling machine and components Cap tucks can occur through misalignment of filling machine components. For proper joining, capsule-filling tooling must be precisely positioned and locked into place. If the alignment is off by a few thousandths of an inch (the thickness of a human hair), or if there is shifting of the tooling or capsule halves because of worn machine b. Poorly formed slugs Figure 2 Powder slug quality a. Properly tamped slug