Tablet press Dust cups and punch seals
In tablet press Dust cups and punch seals are options available to protect the tooling from damage by abrasive nature of blend during compression cycle fines are generated which may get up to the upper punch guides via upper punch seals
Upper punch seals are present inside the punch holes of upper turret
Dust cups , oil cups or bellows are installed below the upper punch tips thereby acting as primary barriers to the product.
Dust cups are of two types Standard and barrel type
Standard dust cups do not come with holes holes are made manually. Standard dust cups protects the tablet from lubrication oil , grease as well prevent the blend from leakage during compression cycle.
Barrel type dust cups comes with precut holes which can be directly inserted into the upper punch barrel groove. Barrel type dust cups does not prevent the blend from leakage as they are installed on barrel but prevents the oil / grease from reaching the tablet.
Another technology, comes with the introduction of bellows these make cushion from the upper punch seals to the groove thereby preventing the oil or grease to reach the blend as well as prevent the deposition of fines on the punch barrel.
Images will clearly clarify the difference between standard and barrel type
Punch seals
Most ignored but important part of tablet press are lower and upper punch seals these seals are made up of silicon and rupture with time in case of ruptured seals the blend will pass to the lower punches and reach fill cam these seals are so critical that some organizations even change them during each changeover.
Punch seals should never be washed with Iso propyl alcohol as it will damage them. However it is most commonly done in most organizations.