Punches lower

Upper punch, lower punch, and die which accommodate one station in tablet press... 

Upper punch lowering cam The upper punches are lowered into the die cavity by the upper-punch lowering cam. This cam is typically CAD optimized to minimize the acceleration and velocity of the upper punch as it enters into the die cavity. In this way, the upper punch travels in a smooth and controlled manner as it enters the die cavity, thus improving weight uniformity. 

A set of tooling consists of upper punch, lower punch, and die. The upper punch has a shorter stem the lower punch stem is longer because it travels longer distances up and down in the die for filling, compression, and ejection, thereby sealing the die hole from below during the entire process of compression. 

Grade XPC is primarily intended for cold punching and shearing. It is more flexible and shows higher cold flow but is lower in flexural strength than... 

Grade XXXPC is similar in electrical properties to Grade XXXP and suitable for punching at lower temperatures than Grade XXXP. This grade is recommended for apphcations requiring high insulation resistance and low dielectric losses under severe humidity conditions. 

Sheet Mica. Pockets of mica crystals ranging in size from a few square centimeters to several square meters are found in pegmatite sills and dikes or granodiorite (alaskite) ore bodies. In order to be used industrially, manufacturers must be able to cut a 6 cm pattern in the mica. "Books" of mica, ranging from 12.9 to 645 cm or more, are cut from the crystals. The books can be punched into various shapes and spHt into thicknesses varying from 0.0031 to 0.010 cm (12). The highest quaUty micas maybe used in aerospace computers, and those of lower quaUty find use as insulators in electrical apphances. 

Tablet Press. The main components of a tablet compression machine (press) are the dies, which hold a measured volume of material to be compressed (granulation), the upper punches which exert pressure on the down stroke, and the lower punches which move upward after compaction to eject the tablets from the dies. Mechanical components deflver the necessary pressure. The granulation is fed from a hopper with a feed-frame on rotary-type presses and a feeding shoe on single-punch presses. A smooth and even flow ensures good weight and compression uniformity. Using the proper formulation, demixing in the hopper is minimized.

The fabrication of all trays may be punched or drilled (more expensive) with 1410 holes, and those in the lower section have blank strips placed over the inlet and outlet edge rows until approximately 1223 holes are left open in the top section above the feed tray. 

The best products have smooth, natural curves and drawn sections that are spherical or nearly so in shape. Their walls will be more uniform, they will be more rigid, their surfaces will be less apt to show tool marks, and their tooling and molds will be lower in cost. Notches or square holes should be avoided when punching formed products. Round holes are preferred to oval ones for minimizing stress buildup. 

Pharmaceutical compressed tablets are prepared by placing an appropriate powder mix, or granulation, in a metal die on a tablet press. At the base of the die is a lower punch, and above the die is an upper punch. When the upper punch is forced down on the powder mix (single station press) or when the upper and lower... 

The major forces involved in the formation of a tablet compact are illustrated in Fig. 14 (a single-ended model) and are notated as follows FA represents the axial pressure, which is the force applied to the compact by the upper punch, FL is the force translated to the lower punch, and Fr is the force lost to the die wall. If one remembers that for every force there must be an equal and opposite force, the following relationship is obvious ... 

Figures 15 and 16 provide a summary of the compression cycles for rotary and single-punch tablet presses. The formation of the tablet compact in these two types of presses mainly differs in the compaction mechanism itself, as well as the much greater speeds achieved with rotary type presses. The single punch basically uses a hammering type of motion (i.e., the upper punch moves down while the lower punch remains stationary), while rotary presses make use of an accordion-type compression (i.e., both punches move toward each other). The former find their primary use as an R D tool, whereas the latter, having higher outputs, are used in most production operations.

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