Punch and die sets

The TS of the compacted samples was determined by transverse compression with a custom-built tensile tester. Tensile failure was observed for all the rectangular compacts when compressed between flat-faced platens at a speed ranging between 0.006 and 0.016 mm/sec. Platen speed was adjusted between materials to maintain a time constant of 15 2 seconds to account for viscoelastic differences the constant is the time between the sample break point and when the measured force equals Fbreak/e in the force versus time profile, where the denominator is the mathematical e. Specially modified punch and die sets permitted the formation of square compacts with a centrally located hole (0.11 cm diameter) that acted as a stress concentrator during tensile testing. This capability permitted the determination of a compromised compact TS and thus facilitated an assessment of the defect sensitivity of each compacted material. At least two replicate determinations were performed for each mechanical testing procedure and mean values are reported. 

Rotary tableting machines work with a number of punch and die sets which move in a circle. The dies are fixed in a round die table and the die table circulates. Together with the dies the lower and upper punches circulate on tracks. The lower punches close the dies. The densification process is bilateral since both punches pass the compression wheels and the force is evolving on the upper as well as on the lower side of the powder bed. The produced tablets show the same hardness on the upper and lower surfaces. 

High-Speed Rotary Tableting Machines High-speed rotary machines work with the same principles as all other rotary machines. They possess a huge number of punch and die sets and often two filling stations. Another possibility is to use punch and die sets which are able to produce several tablets simultaneously. Special tooling can be used for this purpose however this is not the subject of this chapter. As... 

The sensitivity of force measurement is dependent on the distance between the force transducer and where the force occurs. Thus for force measurement, instrumentation of the punches is more advantageous than instrumentation of the machine frame. However, since punch and die sets have to be exchanged between different runs of the machines, instrumentation of the punch holder, the machine frame, or the roller pin is most widely spread. 

Demands from GMP and the necessity of connecting tool sets to tablet products led to the introduction of tooling management with the help of special software (e.g., TM II from Natoli, http //natoli.com/, and Vali-Scan from Holland), where information on each individual encoded punch and die set is collected to provide a tooling life record. The software may be installed on a mobile trolley and the code on each individual tool will be checked while it is set onto the machine. 

The next step in the processing of tape-cast materials is to punch the desired shape in the area defined by the x and y directions. Most production facilities use punch-and-die sets in either a hydraulic or a mechanical press. The shaping process usually is divided into two separate functions that are sometimes combined in simple parts. These procedures will be described in the next sections. 

Punch and die sets are available in both round and square versions. Round dies are most common because of their ease of alignment relative to one another. Square pimches must be accurately aligned both in their center location relative to the die, as well as the rotation of the punch relative to the die. In spite of this additional complexity, square pimches are employed in cases in which very precise square cavities are required. 

The compaction curve analysis described in this paper originates in the ceramics literature [1]. It is a method of plotting force-displacement data obtained during a uniaxial compaction test. The granular sample is loaded into a cylindrical punch and die set and compressed using a mechanical testing machine. The measured force data are converted to pressure and are... 

Fig. I. Test apparatus using a mechanical testing machine and a punch and die set.

Various shearing processes used to cut cold rolled sheet metal with hardened punch and die sets. The most common shearing processes are cutting, piercing, blanking and fine blanking (see 3.8F). 

B5.1M-1985(R1992) Punch and Die Sets External Milling Machine... 

In the past year—to give you an example—the US has been flooded with small amphetamine tablets known as minibennies. Ballistics examination indicates that most of these tablets originate from three sets of punches and dies used on multiple punch tableting machines. To date, over 30 million minibennies have been purchased or seized. 

Straight portion of stem effective inside die bore Portion of punch stem which is undercut or made smaller than punch tip straight most common for lower punches in order to reduce friction from punch tip and die wall Complete set of punches and dies to accommodate all stations in tablet press... 

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. 

In single-punch tablet presses (reciprocating tablet presses), the punches are fixed to the punch holders which travel up and down, and in many cases fixation screws are used. Each make has its own holder design for punches and dies, and consequently for the tooling sets as well. Therefore little can be said in general terms, but it would appear that on the whole the remarks on the rotary press tooling apply correspondingly. 

Fig. 1 General terminology of tooling (sets of upper and lower punches and dies) for rotary tablet presses.

Mechanically powered compaction simulators are also available to replicate the compression event of tablet presses (3). These machines leverage the design of traditional rotary tablet presses where the punches are forced between a set of roll wheels to enable the compression event. The punch type and roll wheels can be changed to replicate the compression event of different press types. In some models, the fill station, compression station(s), and ejection station arc aligned in series on a linear track, where the punches and die travel along this track from station to station to complete the fUl-comprcss-ejection cycle. 

The elongated shot or bullets now used for rifles are made at Woolwich in the following way The machine for this purpose consists of four sets of duplicate punches and dies, independently worked in pairs by two eccentrics, driven by gearing from... 

Punch-and-die press with multiple die sets on an indexed table for making large (e.g. coal) briquettes. (No longer used.)... 

A member of the COMPACTING TOOL SET that determines the powder fill level and forms the bottom of the part in a PUNCH AND DIE PRESS. 

Fig. 6.240 a) Evoluted (straightened) diagram of presses with one or two sets of press rollers in a rotary punch-and-die press, b) Paths of the evoluted presentation [B.71, B.97]... 

The die-set is mounted in the press as a complete self-contained assembly and can be removed and replaced as often as required in the knowledge that accurate alignment of punch and die is always maintained. Change-over times are low, since the complete die-set is removed and replaced by another die-set complete with its punches and dies for a different component. 

In contrast, soft-tooling methods use a computer-controlled punch and die, or a set of punches and die, and CNC. This approach allows for rapid design changes that only require the change of a computer file. These computer files, which are often referred to as drill or punch files, contain a set of X, y coordinates and a punch number for multiple punch machines. Computer programs are used to generate these files from CAD layout programs... 

Canopy machines are difficult to set up. Typically, only a single row of products is cut at a time. As a result, the trim press cycles are far shorter than those of the thermoformer, meaning that frequent maintenance and punch and die interference alignment are often required. 

Normally, the punch and die should be made to give a clearance of 0.0005 in (0.013 mm) or less and the punch should be perfectly smooth and parallel. When punching laminates or fairly hard thermoplastics, flat bottomed punches should be used and these should be set so that the punch enters the die by approximately 0.0005 in (0.013 mm) at the end of its stroke, or rather more if such materials as thin nylon or polypropylene sheets are being punched. In some cases, particularly when softer materials, such as polyethylene or flexible PVC are involved, it will be necessary to use knife-edged tools and to allow the punch to enter the die for some distance, to separate the piece being punched from the strip. However, with all materials, it is important to ensure that the material surrounding the... 

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