【正文】 injection molding technology is a plete process and equipment technology which facilitates extremely high quality and greatly reduces production costs. The MuCell Process involves the controlled use of gas in its supercritical state to create a foamed part. The MuCell Technology is targeted at precision and engineered plastic ponents with maximum wall thicknesses of less than MuCell Process generally offers a 5075% improvement in key quality measures, such as flatness, roundness, and warpage, also eliminating all sink marks. These improvements result from the fact that relatively uniform stress patterns are created in the molded part rather than non uniform stress characteristic of solid a direct result of the uniform stress and shrinkage associated with the MuCell Process (which occurs because the pack and hold phase of the molding cycle is eliminated), the parts that are produced tend to ply far more closely with the mold shape and, presumably, the dimensional specifications of the part itself. This means that when using the MuCell Process, fewer mold iterations are needed to produce a pliant part, saving time and quality advantages of the MuCell Process are plemented by certain direct economic advantages, including the ability to produce 2033% more parts per hour on a given molded machine, and the ability to mold parts on lower tonnage machines as a result of the viscosity reduction and the elimination of the packing requirement that acpanies the use of supercritical gas. This 25 page processing handbook covers all aspects of the process from setup to troubleshooting to optimizing results. It is primarily useful to panies who are manufacturing or are planning to manufacture parts using the MuCell Injection Molding Process. Please contact Trexel for a copy of this MuCell Injection Molding Process involves the highly controlled use of gas in its supercritical state (SCF) to created millions of micronsized voids in thin wall molded parts (less than 3mm). With the correct equipment configuration, mold design, and processing conditions these microcellular voids are relatively uniform in size and voids are created or nucleated as a result of homogeneous nucleation that occurs when a singlephase solution of polymer and gas (monly nitrogen, but occasionally carbon dioxide) passes through the injection gate into the singlephase solution is created through the operation of a conventional injection molding machine which has been modified to allow the creation of a singlephase solution. The key modifications to the system involve the use of a precision SCF delivery system to deliver SCF to special injectors based on mass flow metering principles. The SCF is then injected into the barrel where it is mixed with the polymer via a specially designed screw. A shut off nozzle maintains the single phase solution while the injection molding screw maintains sufficient back pressure at all times to prevent premature foaming or the loss of pressure which would allow the single phase solution to return to the two phase solution. Trexel has recently published a prehensive MuCell Process Guide in English, Chinese, Japanese, and German which explains in step by step detail how to apply the MuCell process in the manufacture of MuCell Injection Molded ponents. This 25 page processing handbook covers all aspects of the process from setup to troubleshooting to optimizing results. It is primarily useful to panies who are manufacturing or are planning to manufacture parts using the MuCell Injection Molding Process. Please contact Trexel for a copy of this MuCell microcellular foam injection molding process for thermoplastics materials provides unique design flexibility and cost savings opportunities not found in conventional injection molding. The MuCell process allows for plastic part design with material wall thickness optimized for functionality and not for the injection molding process. The bination of density reduction and design for functionality often results in material and weight savings of more than 20%. By replacing the pack amp。 hold phase with cell growth, lower stress parts are produced which have enhanced dimensional stability and substantially reduce warpage. Cell growth also res ults in the eliminatio n of sink marks. Unlike chemical foaming agents, the physical MuCell process has no temperature limitation and does not leave any chemical residue in the polymer。m in size. Typically these foams are rigid, closedcell structures。C to introduce the microcellular structure without an appreciable density change, to increase the fatigue life of a part. Due to the low processing temperatures, very little dimensional change was observed in the experiments. The tensile data for all gaspolymer systems investigated falls on one reduced plot where relative tensile strength can be plotted against the relative density, as is shown in Figure . However, energy absorption measures, such as an impact test, are more sensitive to variations from polymer to polymer, and the results cannot be generalized. Gardner Impact Strength for PVC foams [11] with relative densities of and higher. It is seen that the impact strength decreases linearly with foam density. This result is contrary to the popular belief, long held without proof, that the microcellular structure will always improve the energy absorption behavior due to the increased resistance to crack propagation offered by the micro voids [12]. Some studies have investigated the relations between the key processparameters in MuCell_ technology and produced cellular foam structure[1,5,6]. It was found that the pore morphology in MuCell_ process couldbe adjusted through varying the process parameters. However, there iscurrently no literature regarding the effects of mold design on the poremo