In the reaction injection molding (\"RIM\") process, stoichiometric amounts of l

Question

In the reaction injection molding ("RIM") process, stoichiometric amounts of low viscosity reacting mixture are pumped through a mixing chamber into a mold, where a polymerization reaction occurs and a solid, shaped object is formed. RIM is a lower energy process than the more common injection molding process, where a high viscosity polymer melt is injected in to the mold. Below is a schematic of the process, where Pa is the entry pressure of the reacting mixture (entering on the left side) and Po is the pressure in the mixing chamber. The part mold is off to the right of the figure (not shown). For the following dimensions and a fluid with a density of 1200 kg/m^3 and viscosity of 0.1 Pa s, determine what the flow rate is through the system if Pa-Po is 400kPa. You can assume that the contraction loss from the reservoir (center chamber) is the dominant loss in this system. D_1 = 9.5 mm D_2 = 1 mm D_3 = 3.2 mm l_2 = 1.5 mm l_2 = 25.4 mm

Explanation / Answer

A1 = .7854 x D1 x D1;; A2 =.7854 x d2 x d2 ; A2/A1= 1x1/(9.5x9.5) =0.011; K from tables = 0.41 ; Head loss = (V2xV2/2g)x 0.41 ; V2 sq = 8002.73 V2= 89.46 cm/sec   Flow rate =0 .7854 x.1 x .1 x 89.46 liters /sec =  0.7 liters /sec =1.2x0.7 = 0.84 Kg /sec = 50.4 Kilogram / minute             

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