Injection molding machine melting capacity

Injection-molding machines are rated by their capacity to mold polystyrene in a single shot. Thus a 2-oz machine can melt and push 2 oz of general-purpose polystyrene into a mold in one shot. This capacity is determined by a number of factors such as plunger diameter, plunger travel, and heating capacity. 

Thermal decomposition of the concentrate and compound samples was carried out using a Ray-Ran benchtop injection molding machine. This unit resembles an oversize melt index plastometer and is equipped with a heated barrel, die and plunger assembly. The capacity of the barrel is approximately 20 g. 

PLA-based composites with polyhedral ohgomeric silsesquioxane (POSS) can be prepared via melt mixing in a twin-screw micro-compounder. The molten, compounded mixture was molded using an injection molding machine to form the composite material [69]. The addition of POSS acted as a plasticizer and enhanced energy absorption capacity. Maximum fracture strength was observed for 7 wt% addition of POSS in the composites [69]. 

For injection molding machine, a minimum of three zone heating control of the cylinder is necessary for required temperature control. Although the thermal stability of LC melt is always high, the shortest melt residence time is adopted (less than 5 minutes) in the cylinder, i.e., the capacity of the machine almost matches with the input weight for the injection molding machine ( 50 to 75% of the machine s input capacity). 

To determine whether the standard of product quality can be maintained throughout the production run, the total weight of plastics material being injection molded per hour should be compared with the rated plasticizing capacity of the machine. If it is greater than the plasticization capacity then, the molding machine is unable to sufficiently plasticize the material so as, to achieve a uniform melt quality, for example, a uniform viscosity. Therefore the molded components will be subject to some variation (e.g. dimensional or visual). It is particularly important to... 

Plasticating capacity n. Of an extruder or injection molder, the maximum rate at which the machine can melt room-temperature feedstock and raise it to the temperature suitable for extrusion or molding. This rate is determined mainly by the quotient of the available screw power, divided by the means specific heat of the... 

Before leaving this section, we should make a few comments on the size and features of //IM machines (see Giboz et al., 2007). Typically the screw ranges from 5 to 16 mm in diameter. Some systems use a screw to plasticate the polymer and a plunger to push the melt into the mold. The clamping force mns from 49 to 147 kN, the injection capacity is from 0.082 to 10 cm, the injection pressure is from 1700 to 3500 X 10 Pa, and the injection speed is from 180 to 1200 mm/s. 

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