Reduction ratios

The exact amount of lubricant required for extmsion depends on the design of the extmder, the reduction ratio (ie, ratio of the cross-sectional preform area to the cross-sectional area in the die), and the quality of the lubricant. A low lubricant content results in a high extmsion pressure, whereas a high lubricant content causes a poor coalescence and generates defects in the extmdate. 

Different resins have been developed for use in different reduction—ratio appHcation ranges (111,112). The powders suitable for high reduction—ratio appHcations, such as wire coatings, are not necessarily suitable for the medium reduction—ratio appHcations, such as tubings, or the low reduction—ratio appHcations, such as thread-sealant tapes or pipe liners. AppHcations and processing techniques are being used, which utilize the unique combination of properties offered by PTFE in fine powder form (113—115). 

Many attempts have been made to develop models which predict the behavior of materials undergoing size reduction. One proposal is that the energy expended in size reduction is proportional to the new surface formed (5). Another theory is that the energy required to produce a given reduction ratio (feed size product size) is constant, regardless of initial feed particle size (6). Practical results show, however, that both these theories are limited in their usehilness. 

High reduction ratios with low power and maintenance are features of pan crushers. 

Sometimes a product that does not meet these requirements must be adjusted by adding a specially crushed fraction. No crushing device available will give any arbitrary size distribution, and so crushing with a small reduction ratio and recycle of oversize is practiced when necessary. 

Smooth jaws produce more numerous flaky pieces than corrugated jaws. Curved jaws produce less fines but more numerous flaky particles. Crusher speed has little effect. The presence of material too small to be crushed has a deleterious effect on the shape of products. Secondary crushers with a small reduction ratio can improve the shape of primaiy crushed material, but secondaiy crushers are not inherently different from primaiy crushers. Slotted screens can remove flaky particles from the product. Impact crushers produce fewer flaky particles than any other type. 

If the rock is abrasive, the first stage of crushing may use gyratory or jaw crushers, otherwise a rotor-impact mill. Their reduction ratio is only 1 12 to 1 18, so they often must be followed by a hammer mill, or they can feed a roll press. Rotor crushers have become the dominant primaiy crusher for cement plants because of the characteristics. All of these types of crushers may be installed in moveable crusher plants. 

Speed Reducer Number Type Model Manufacturer Reduction Ratio AGMA Mechanical H.P. Rating Sen/ice Factor at Rated H.P. of Driver No. of Reductions ... 

Importance - calculates and displays three importance measures, Fussell-Ve.scly, Risk Reduction Ratio, Risk Increase Ratio, for each event in the system, sequence, or end state. 

Assumes that the power required is constant with size reduction ratio (e.g. the energy required for 1 mm 0.5 mm = 10 cm 5 cm = — 1)... 

The worm thread is a major factor in worm ratios and is an important feature in worm design. The speed-reduction ratio is equal to the total number of worm-gear teeth divided by the number of worm threads. 

Roll crushers are made either smooth or with teeth. A 24 in. toothed roll can accept lumps 14 in. dia. Smooth roiis effect reduction ratios up to about 4. Speeds are 50-900 rpm. Capacity is about 25% of the maximum corresponding to a continuous ribbon of materiai passing through the roiis. 

Figure 188 shows how much the volume of tank would be reduced by latent heat of water. Although the reduction ratio depends on temperature... 

Figure 23. Influence of the conveying velocity on the reduction ratio of sea salt (the reduction ratio is defined as the ratio of the surface mean diameter before and after conveying. (McKee et al., 1995.)...

P.R.150 is of limited regional significance. Depending on the area of application and on the reduction ratio, the pigment affords shades from bluish purple to carmine. P.R.150 is used in textile printing. In PVC coloration, which used to be its main market, it has been superseded by other products. 

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