Increase Of Injection Temperature Research Articles

Investigations of the effect of injection parameters on the dimensional accuracy of wax patterns used in ceramic shell investment casting

The present investigation is aimed to determine the effects of injection parameters on the dimensional accuracy of the wax patterns, produced by wax injection machine, to be used in ceramic shell investment casting process. The injection parameters viz. time, temperature, die temperature and holding time were considered. Experiments were performed and optimal parameters were determined. Linear and volumetric contractions of wax patterns were measured and dimensional variations were evaluated. Results reveal that an increase in injection temperature increases wax shrinkage, whereas increase in die temperature reduces the wax shrinkage. Slow injection and short holding time reduces dimensional variation in castings.

EFFECT OF OBSTACLE IN RIVER ON THE HEAT DISSIPATION OF HOT WATER INJECTION

Numerical analysis of the cooling process of hot water discharge from a steam power plant into a river has been carried out in the present study. A mathematical model describing the flow field and temperature distribution induced in the river as a result of the cooling process is made based upon the assumptions of steady state, two-dimensional, turbulent flow, in the horizontal plane. The governing equations are the continuity, the momentum, the (К-ε) turbulence model and the energy equation. A proper initial and boundary condition are specified to be used in the solution of the governing equations. A numerical solution of the governing equations is made by using the control volume approach, with non-staggered grid technique and modified SIMPLE algorithm. The numerical solution is capable of calculating the velocity and temperature distributions of the calculation domain. The numerical results show that the developed algorithm is capable of calculating the flow field, properly and accurately. Results are obtained for ten cases of configuration, constant aspect ratio and weather conditions for Baghdad. The results show that the injection velocity effect on the temperature distribution and stream line , the exist of obstacle and its distance from the injection zone but the increase in injection temperature cause a small effect on temperature distribution and stream line.

Injection of Thermoplastic Polyurethane to Fix Diamond Beads on Wire Saws

An investigation was reported of the injection of thermoplastic polyurethane (TPU) to fix diamond beads on wire saws. Effects of injection material hardness, injection temperature and dwell pressure on the mechanical properties of three types of TPU plastics were studied and the results showed that with the increase of material hardness, both the 100% Modulus and the tensile strength of TPU were improved, but the rupture extensibility reduced. With the increase of injection temperature, the tensile strength increased but the rupture elongation decreased. To every type of TPU, a minimum injection temperature can be found for an ideal density of TPU.

Study on Processing Parameters of Ceramic Injection Moulding

According to the heat transmission theory, in the aid of computer, the temperature distribution in the cylinder cavity was calculated. The temperature of the mould has much influence on the time for the injection material’s temperature of the cavity center to drop to the injection material softening temperature. The influence of the processing parameters on the density of the injection molding specimens was also investigated. It turns that the injection molding specimens’ density changes little with the increase of injection temperature and pressure, but changes a lot with the increase of holding pressure time.