TABLETING 61
Allowable deviation Generally, an increase in land width
will strengthen the punch and reduce the likelihood of cup deformation or breakage while allowing for higher compression forces and extended tool life. An experienced tooling manufacturer can help navigate the design process to ensure a successful tableting project, and a CAD software program, such as Natoli Engineering’s TabletCAD, can provide convenient, real-time feedback on your tablet designs.
Top view and side view of tablet land
creates nearly vertical surfaces, and the cup will be more susceptible to abrasion. Punches with compound cups incorporated into their designs can result in a steeper slope of the cup where it is adjacent to the inner edge of the land. Tat slope is greater than that of a single- radius cup, which reduces edge strength and the allowable tip force. Tis type of cup design isn’t as robust as a standard cup. Terefore, land becomes even more critical because it compensates for much of the strength lost due to the steeper slope.
Wear on the land and tip Land is the area of the cup most susceptible to wear, and it should be inspected
regularly. Identifying wear of the tip edge by visual inspection is quite challenging, especially without magnification. A traditional micrometer cannot properly check tip-edge wear. Te quickest and most efficient method is to use a horizontal optical comparator, which is often simply called a comparator. In operation, a comparator projects a magnified silhouette of a punch tip on a screen, usually at 10x magnification but sometimes at 20x or greater, which enables easy inspection for wear and even measurement against prescribed limits. A comparator is a valuable piece of equipment. In fact, it is the only efficient method to check punch-tip wear; unfortunately, it is not used often.
Land wear from granulation
Bill Turner and Kevin Queensen are with Natoli Engineering.
www.natoli.com
www.scientistlive.com
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