Incremental pressing

The increments should be less than the diameter of the charge each time to maximize the effect of this method. Although pressure and density gradients are reduced, they are not completely eliminated in this method and are proportional to the number and size of increments used. However, interfaces between the increments have been found to cause initiation problems in some cases. 

The casting, extrusion and pressing of explosives is always done behind a shield. 

In production facilities, the air or hydraulic supply to the press is cut off when the shield (door) is in the open position. In some facilities, removable shields are also used. The operators work behind the shields which are placed in front of the facility. 

The pressed and cast formulations can also be machined afterward if required but this is carried out remotely because of the hazards involved during the machining process. Also, the tools which are used for machining purpose should be of non-sparking type viz. made of brass or beryllium-copper alloy. 

Explosives such as PETN, RDX, HMX cannot be used as such for pressing because of their sensitivity and granular nature. The sensitivity is reduced considerably to safer limits by coating them with waxes or polymers. This process is called phlegmatizahon. In some cases, zinc stearate, barium stearate, graphite etc. 

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Figure 3.1 Incremental pressing technique. Based on Reference [3].

A small amount of particleboard is made with a fire-retardant treatment for use in locations where codes require this material, as in some offices and elevators. Particleboards receive overlay and finishing treatments with ease. Wood veneers, melamine overlays, printed paper overlays, vinyl overlays, foils, and direct grain printing can all be done quite simply. A small amount of particleboard is also made in the form of shaped, molded articles such as furniture parts, paper roU plugs, bmsh bases, and even toilet seats. There is another small increment of particleboard made by the extmsion process. These products are made in small captive operations owned by furniture manufacturers which consume all of this production in their furniture. The extmsion process differs from conventional flat-pressed particleboard in that the wood furnish is forced between two stationary heated surfaces. The mats are formed from one edge and this edge is alternately formed and pushed between the heated platens, which are maintained at a distance equal to the thickness of board produced. This is an old, slow, small-scale process, but is stiU in use in at least one location. 

The number of components N is incremented by one and the entire procedure is repeated to arrive at a PRESS(A + 1). In other words, for A + 1 = 2, two principal components would be extracted and used to predict the deleted data values. As N approaches the tme number of significant components, the prediction should improve, and thus the PRESS should decrease. As the significant number is passed, noise begins to be included within the model, which has low predictive abiUty. At this point, the PRESS should start to increase again. Thus the basic type of criterion used in cross-vaUdation to select is that when... 

Prior to WWII, armor-piercing projectiles were press-loaded with Explosive D. This required the application of pressures of the order of 10,000 to 12,000psi to successive increments of the charge and was a slow and expensive operation. The development of armor-piercing bombs necessitated the use uf an in sensitive expl that could be melt loaded and for this reason,... 

Theisen C, Johann C, Deacon MP, Harding SE (2000) Refractive Increment Data Book for Polymer and Biomolecnlar Scientists. Nottingham University Press, Nottingham, UK... 

Huglin, M. B., Specific refractive index increments, in Light Scattering from Polymer Solutions, Huglin, M. B., Ed., Academic Press, New York, 1972, chap. 6. 

In-situ x-ray diffraction (XRD) was performed on a coin type cell with a 4x6 mm Kapton window coated with conductive thin copper layer. The graphite electrode was pressed against the Kapton window so as to be reached by the x-ray beam. After several lithiation/delithiation cycles under a C/10 rate between 1.5 and 0V, the cell was fully delithiated up to 1.5V. The cycle capacity achieved with the graphite electrode is about 360mAh/g. The cell was then re-lithiated under a slower rate of C/20. XRD patterns were taken for about five minutes every hour while the cell is under continuous discharge. As result the lithium composition x in LixC6 was incremented by 0.05 between two successive XRD scans. 

G. Geiseler, M. Ratzsch, K. Ebster and E. Ziegel, Ber. Bunsenges. Phys. Chem., 70, 221 (1966). J. D. Cox and G. Pilcher, Thermochemistry of Organic and Organometallic Compounds, Academic Press, London, 1970. In addition, the universal methylene increment has been a major tool in our analyses of literature thermochemical data in many of our earlier Patai/Rappoport chapters, e.g. References 8 and 9. 

The Sweep variable is set to Temperature. We have chosen a linear sweep with temperature going from -25°C to 125°C in 1°C increments. Click the OK button to return to the schematic. Select PSpice and then Run to simulate the circuit. When the simulation is complete, display the traces V(Vexp), V(Vquad), V(Vlin), and V(Vx) to display the value of each resistor (to add traces press the INSERT key) ... 

The synthesis of the n=2 phase is similar to that described above for the n=l system. In general, stoichiometric portions of oxides and carbonates (or nitrates) are ground and reacted in a high density alumina crucible at temperatures between 800 and 820°C. The product is crushed and pressed into a pellet for further heat treatments at 840-870°C. The firing temperature must be raised incrementally to prevent melting of the sample. 

LEAD AZIDE. 400 GRAM PRESSED IN 2 INCREMENTS OF. . 200 GRAM EACH... 

The pressure most frequently specified for charges used in military items is 10000 psi. Charges may be pressed directly into their containers or pressed.into molds and ejected as pellets. Where they are pressed into containers of lengths greater than the diameter, the explosive is usually loaded in increments... 

The relationship between loading press and charge density for commonly pressed expls is given in Table 1 (Ref 1). An approximation of the loading densities of six commonly used explosives is shown in the nomograph, Fig 5 (Ref 3). The pressure-density relationship varies somewhat from lot to lot. In addition, loading density is affected by such factors as ram clearance and increment length... 

In addition to the pressing properties of the expl as such, the relationship between loading press and density is affected by such factors as ram movement, clearances, increment size, and the coeff of friction between expl and case. 

This technique was developed to overcome the problems associated with direct pressing. In this method, the entire quantity of explosive is not pressed at one time but explosive is added and compacted incrementally until all explosive material has been pressed to the required density (Figure 3.1)... 

Variations in the density of the pressed compositions do occur, particularly near to the surface resulting in an anisotropic product. Pressing in incremental stages or using two pistons can reduce these variations as shown in Figures 7.4 and 7.5, respectively. 

A usuable end item design used a steel sleeve held in the traverse hole of a Mg slug by the delay element (See Fig). The steel sleeve had a high impact polystyrene end cap. The cartridge contd 7.8g of photoflash compn (as above), aj0.6 1 height of 93/7 Ba chromate/boron delay compn pressed in 3 increments, a relay, and a propulsion system (1.4g of 85/10/15 BaCrOA/boron/Mgtplus 1.4 grains of Type A3 BkPdr... 

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