Metal injection molding production process in the case of technical progress
Modern MIM technology began in the early 1970s.Into the 1990s, with the further improvement of MIM technology, new materials, new technology constantly emergingl0.So far, the United States, Europe, Japan and other countries and regions of the companies engaged in the technology product development, research and marketing.There are typical Pacific Metals, Mitsubishi Steel, Sumitomo, etc.Among them, the German BASF, with its unique feed to make the precision of the injection molding processing + 0.1% level, so that the injection molding products can be comparable to conventional powder metallurgy products accuracy
●Currently,the metal injection molding were concentrated and active area of research.
The MIM powder and milling technology, carbonyl method, ultra-high pressure atomization method, micro atomization method, laminar flow atomization method and so on.
●Adhesive, including thermoplastic system, gel system, thermosetting system, water system
●Injection molding, metal injection molding process computer simulation.Computer simulation including the simulation of powder injection feeding performance parameters and powder injection molding filling mold flow simulation, etc.MIM computer simulation commercialize software C-MOLD, MOLDFLOW, CADMOULD, IDEAS system, TCOP software, MOKDCOOL etc.
●Degreasing, according to the different system, degreasing methods are varied. Typically include: Wiech , Injectamax , water dissolving , Metamold.
●Sintering and heat treatment, the typical vacuum sintering, continuous skim sintering, heat treatment and sintering integration research and so on.
Metal injection molding of the many advantages has been widely noticed by the industry, the world’s advanced countries on their great interest, especially in Asia, with the development of the electronics industry, the fast development of micro-injection molding.The actual production process,due to the particularity of product market and the product. among other factors,njection molding and many problems restricting its development, some have the serious influence the development and application of the product.At present, the metal injection molding process has the following several aspects of problems to be settled urgently.
1.Shrink feature modeling and product design mold.
The technology of metal injection molding with a large amount of binder, so when the sintering shrinkage is very large, its line shrinkage rate generally 13 to 25%, especially the product surface transition inflection point and different wall thickness in line with the overall more significant difference shrinkage rate, thus there is a deformation control and the dimensional accuracy control problem.Especially since the MIM products mostly complex shape profiled, this problem become more prominent.Uniform feeding for the final sintered product size precision and deformation control is a key factor, but the most core technology is based on the mathematical model of thermal shrinkage characteristics of different material forming products mold design.
2.Injection molding is the press of feeding the molten body with high pressure into a mold cavity, let its cooling and solidification, which are required for the process of shaped parts.Feeding in molten state is not a Newtonian fluid, its full of cavity process is an unsteady and non-isothermal flow process.Powder injection molding product defects are mostly produced in the forming process, and some defects cannot eliminate in the subsequent debinding and sintering process.,Experimental study time consuming goods, and some parameters itself cannot be obtained through experiments.With the development of computer and numerical calculation technology, using numerical methods to analyze the simulation of injection molding process, and the feeding pressure, melt temperature, the change of the parameters such as flow rate distribution, study the influence law of process parameters, the optimum technological parameters combination are obtained.
3.Optimization of the injection molding process.
Groped through the experiment to determine the solvent degreasing and combining the thermal degreasing process, and find the best for each parts, skim degreasing time and drying temperature.
Sintering to eliminate the pores between the powder particles, making the MIM products meet full density or close to full densification.The sintering process on the microstructure and properties of final products greatly, and even decisive influence.Sintering process is mainly to determine the rational and scientific sintering atmosphere, sintering temperature and sintering time.