Solvent de binding of water soluble binder in powder injection moulding

The solvent debinding of water soluble binder in powder injection moulding (MIM) was investigated systematically, including the effects of solvent types, temperature and the thickness of green parts on the solvent debinding rate. After studying the debinding of a green part with a thickness of 4.26 mm, it was found that, the debinding rate of polyethylene glycol(PEG) in water and alcohol was high initially, and then decreased; however, it would increase with temperature increasing. At room temperature, the dissolution rate of PEG in water was higher than that in alcohol, but the latter would be much faster with temperature increasing because the debinding activation energy in alcohol was 51.44 kJ·mol -1 ·K -1 , much higher than 24.23 kJ·mol -1 ·K -1 in water. With a green part thickness larger than 4.26 mm, the debinding was controlled by diffusion; but with that smaller than 2.36 mm, the debinding was controlled by both dissolution and diffusion.

MATHEMATICAL AND PHYSICAL MODELING OF INTERFACIALPHENOMENA IN CONTINOUS CASTING MOULD WITH ARGONINJECTION THROUGH SUBMERGED ENTRV NOZZLE

The study on the fluid flow, meniscus oscillation, slag entrapment in continuous casting mould was conducted mathematically and experimentally. The results show that the injection of argon into submerged nozzle enhances the meniscus oscillation, thus increases the probability of slag entrapment, and the critical argon blowing flow rate, which will give rise to slag entrapment, is around 10l/min. The trajectory of bubble is affected by the bubble diameter and the molten steel flow, and the bubble diameter is dominant. The bubble with diameter 1.4mm floats fastest with 0.47m/s terminal velocity.

Bi-phasic Simulation of Metal Injection Moulding:Constitutive Determinations

To predict the segregation effect in metal injection moulding (MIM) injection, a bi-phasic model based on mixture theory is adopted in simulation. An explicit algorithm is developed and realized by the authors, which conducts the simulation to be a cost-effective tool in MIM technology. In case of the bi-phasic simulation, the viscosity behaviours are necessary to be determined for the flows of each phase while only the viscosity of mixture is measurable by tests. It is a crucial problem for application of the bi-phasic simulation of MIM injection. A reasonable method is hence analysed and proposed to determine the viscosity behaviours of each phase. Even though this method may be furthermore modified in the future, it results in the practical simulation of segregation effects with reasonable parameters. The simulation results are compared with the measurements on injected specimens.

Study on Injection Moulding of High Precision Aspheric Plastic Lens

With the rapid development of information and multi me dia technologies, the demand for the optical plastic aspheric elements used in o pto-electronic devices, camera, optical disc and projector lens etc. has been i ncreased rapidly in the recent years. The key technologies of fabrication of asp heric plastic lens are the design and manufacturing moulds, selection of proper injection moulding equipment, and optimization of injection moulding parameters etc. In this paper, the effect of injection pressure, moulding temperature, cool ing time and injection speed on the surface profile of the lenses during injecti on and holding process is investigated. Surface quality of plastic lenses is mea sured by Talysurf Texture Measuring System. The experimental results showed that the injection pressure and moulding temperature are important parameters compar ing to cooling time and injection speed. A bit change of injection pressure or m oulding temperature will affect the property of the surface profile. Either incr easing injection pressure or mould temperature can achieve less shrinkage. Other wise, a lower injection pressure will produce more shrinkage, more air traps and a lower mould temperature results greater warp and higher shrinkage. The dynami c process of injection for optical plastic lenses is simulated by 3D Moldflow pl astic Insight software (MPI). The MPI will help us to optimize injection mouldin g parameters.

Permeable Steel and Its Application in Plastic-injection Mould

The gas in plastics mould has great influence on performance, appearance and lifespan of the injection molded parts. Venting channel and its appendix system should be used for gas exhausting in general. However, the dependence on the venting system complicates the mould design. Furthermore in certain condition, it is difficult to integrate the venting system into the mould. Currently a kind of mold material which has gas permeability has been developed in abroad, but the applications of this mold material were restricted by its higher cost and smaller size. In this research, a porous material which was made by powder metallurgy was applied to plastic mould to replace the venting system. Permeability of the steel with different secondary processing was tested and compared with a special apparatus. The metallographic samples of the steel with different secondary processing were prepared and investigated. Finally an actual injection set was established to investigate the applications of permeable steel. The metallographies indicate that the micro-holes inside permeable steel were interconnected. Moulds made of permeable steel exhibit good permeability in the plastic-injection experiments and gas generated in the mould cavity was smoothly exhausted. The melted plastic did not penetrate into the mould or block in the micro-holes. After several times of plastic-injection experiments, the mould still retained good permeability. The strength of this permeable steel is between 200–250 MPa and suitable for industrial applications. The venting systems simplified by permeable steel in plastic-injection have simple structures, which can be applied into any place that requires gas exhausting.

The Comparison Between Finite Element Analysis and Experimental Results of the Cooling of Injection Moulds with Hot Runner System

In an injection moulding process, the mould cooling s ystem is very important as an efficient and uniform cooling effect can improve b oth the productivity and part quality. Due to the complexity of the process, muc h research on the mould cooling analysis and cooling design optimization has bee n focused on the core and the cavity, excluding other systems of injection mould s. However, the runner system introduces a considerable amount of heat into the mould. In recent years, more and more hot runner systems are being applied in th e moulding industry to save material and decrease losses of injection pressure. This raises the need to include the hot runner system in the cooling analysis. I n this paper, a photo frame part was studied. The mould was built with a hot run ner system. Two thermal sensors were installed: one measures the temperature of lateral surface of hot runner nozzle; the other measures the plastic temperature from the core side. A pressure sensor was also installed to measure the pressur e of the core impression. Cooling analysis was performed using ABAQUS, ananalysi s software based on the Finite Element Method (FEM). The assembly including core , cavity and plastic part was modeled. Heat conduction from hot runner to cavity and from polymer melt to the mould and force convection on the cooling channel surfaces were studied. The natural convection between the ambient air and the ex terior mould surface was ignored. The simulations were adjusted with the experim ental results to find out the heat input from hot runner and its influence on mo uld cooling. Finally, the optimal cooling design and optimal injection condition were obtained.

A Case Study of Heat Transfer from Hot Runner Mould to the Fix Platen of the Injection-moulding Machine

In an injection moulding process, the parallelism b et ween the tie bars of the injection moulding machine is very important as it will affect the mould closing and clamping system. In recent years, more and more ho t runner systems are being applied in the moulding industry to save material and decrease the losses of injection pressure. Heat transfer from hot runner system from the fixed half which is secured in the fix machine platen could transmit s o much heat that it may cause high temperature differential between the machine fix platen and moving platen. This will cause the tie bar to become unparallel. Part quality will be compromised and the wear of the tie bar will be excessive. Overhaul of the tie bar may be necessary after a short period of time which is c ostly. This raises the need to analyze the heat transfer from the hot runner sys tem to the machine fix platen and the methods of isolating or minimizing the hea t transfer. In this case study, a photo lens article mould was used. The mould w as built with a direct hot runner nozzle system. Heat conduction from hot runner and machine screw to machine fix platen were studied based on either using high temperature heat insulating plate put in placed between the mould and the mould ing machine fix platen or drill cooling channels in the front mould clamping pla te. The high temperature insulator is very costly as it is made out of glass re inforced polymer composite material. Experimental results were obtained and anal yzed to find the best method to minimize the unwanted heat transfer using the ch eapest and most effective method.

Effect of weld line positions on the tensile deformation of two-component metal injection moulding

Knowledge of the mechanical properties of two-component parts is critical for engineering functionally graded components. In this study, mono-and two-component tensile test specimens were metal injection moulded. Three different weld line positions were generated in the two-component specimens. Linear shrinkage of the two-component specimens was greater than that of the mono-component specimens because the incompatibility of sintering shrinkage of both materials causes biaxial stresses and enhances sintering. The mechanical properties of 316L stainless steel were affected by the addition of a coloured pigment used to identify the weld line position after injection moulding. For the two-component specimens, the yield stress and ultimate tensile stress were similar to those of 316L stainless steel. Because 316L and 630(also known as 17-4PH) stainless steels were well-sintered at the interface, the mechanical properties of the weaker material(316L stainless steel) were dominant. However, the elongations of the two-component specimens were lower than those of the mono-component specimens. An interfacial zone with a microstructure that differed from those of the mono-material specimens was observed; its different microstructure was attributed to the gradual diffusion of nickel and copper.

The most economic cavity quantity in injection mould CAD based on concurrent engineering

Presents the conception of concurrent engineering employed for CAD/CAM of injection moulds by closely combining the management science with the manufacturing techniques with the cost of processing, material cost, etc taken into consideration from the conceptural design to delivery of products and concludes with the results of analyses that the cost of finished plastic parts is lower, the production efficiency is higher while energy is saved.

Application of Standardization for Initial Design of Plastic Injection Moulds

Today, the time-to-market for plastic products ar e getting shorter, thus the lead-time for making the injection mould is decreasin g. There is potential in timesavings in the mould design stage because the design process that is repeatable for every mould design can be standardized. T he preliminary work of any final plastic injection mould design is to always pro vide an initial design of the mould assembly for product designers (customers) p rior to receiving the final product CAD data. Traditionally and even up till no w, this initial design is always created using 2D CAD packages. The information used for the initial design is based on the technical discussion checklist, in which most mould makers have their own standards. This checklist is also being used as a quotation since the most basic information of the mould in the particu lar project is being recorded in it. The basic information in this checklist in cludes the number of cavities, the type of mould base to be used, the moulding m achine to be used for the moulding, the type of gating system, the type of resin material used and its shrinkage value etc. Information on special requirements such as the number of sliders or lifters to be used is also listed in the check list. At this stage, there is still no information on the cooling and ejection design since they are greatly dependent on the final product CAD data. This res earch focuses on the methodology of providing the initial design in 3D solid bas ed on the technical discussion checklist, which takes the role of the overall st andard template since every sub-design has its own standard template. An examp le of a sub-design that has its own standard template is the cavity layout desi gn. The cavity layout for plastic injection moulds can be designed by controlli ng the geometrical parameters using a standardization template. The standardiza tion template for the cavity layout design consists of configurations for the po ssible layouts. Each configuration of the layout design has its own layout desi gn table of all the geometrical parameters. This standardization template is pr e-defined in the layout design level of the mould assembly design. This ensure s that the required configuration can be loaded into the mould assembly design v ery quickly without having the need to redesign the layout. This makes it usefu l for technical discussions between the product designers and mould designers pr ior to the manufacture of the mould. Changes can be made to the 3D cavity layou t design immediately during the discussions thus the savings in time and avo idance of miscommunications.

Optimization of Process Parameters for Injection Moulding of Nylon6/SiC and Nylon6/B_(4)C Polymer Matrix Composites

In this research study,the mechanical properties of several Polymer matrix composites are investigated.These composites are multi-phase materials in which reinforcing materials are properly mixed with a polymer matrix.More precisely,Nylon 6 reinforced with 5,15 and 25 wt.%of silicon carbide(SiC)and Nylon 6 reinforced with 5,15 and 25 wt.%of boron carbide(B_(4)C),prepared by means of an injection moulding process at three different injection pressures are considered.Specific attention is paid to the tensile and impact strength of these composites.The Taguchi technique is used to optimize the process parameters such as reinforcement material,its percentage and the injection pressure.It is observed that the specimens 5%SiC with 80 MPa injection pressure display a better tensile strength and similarly the specimen 5%B_(4)C with 90 MPa injection pressure have a superior impact strength.

Genetic Algorithm for Injection Mould Design and Moulding

Obtaining the optimal values of the parameters for th e design of a required mould and the operation of the moulding process are diffi cult, this is due to the complexity of product geometry and the variation of pla stic material properties. The typical parameters for the mould design and mouldi ng process are melt flow length, injection pressure, holding pressure, back pres sure, injection speed, melt temperature, mould temperature, clamping force, inje ction time, holding time and cooling time. This paper discusses the difficulties of using the current computer aided optimization methods to acquire the values of the parameters. A method that is based on the concept of genetic algorithm is proposed to overcome the difficulties. The proposed method describes in details on how to attain the optimal values of the parameters form a given product geom etry.

Design of Large Injection Mould for Car Dashboard

The dashboard is the most important part of the large inner decoration of cars;it should not only have enough strength and rigidity,but also have a harmonious body model which can unify the theme.Besides,it needs to reach the goal of lightweight.In order to achieve these three goals,the car dashboard is made by engineering-plastics and adopts the technology of injection moulding.This paper introduces the keys of design and the advanced technology of large injection moulding for car dashboard.

Study on the Injection Molding and Optimization of Radiator Cap based on CAE Technology

In order to improve the radiator cap of the automobile cover forming quality and efficiency, this paper applies the UG software to carry out the design of the injection mold, and use Moldflow software to simulate and analyze the position of gate filling, flow, cooling and other aspects of application, to determine the best inject location and optimize die structure design. The research results show that the combination of CAD and CAE technology can effectively improve the mold design quality, shorten die development cycle, and reduce the cost of development.

基于UG的拖拉机大灯注塑模具设计

以拖拉机大灯为例,分析了UG注塑模具建模的设计方法和工艺方案,建立了拖拉机大灯模型,并完成了拖拉机大灯注塑模具的设计。研究结果表明:经过UG模拟开模出来的塑料件没有出现气泡、变形、缺料和银线等缺陷,整体也没有发现熔合条纹,设计的拖拉机大灯注塑模具满足设计需求。

基于PC/ABS薄壁成型的雾化器机筒注射模设计

针对雾化机机筒薄壁塑件模腔流长比为77.8,并且采用PC/ABS进行注塑要求的特点,设计了1副两板2次开模的自动化注塑成型。模具中,针对塑件模腔的浇注,设置了2个潜伏式浇口,保证模腔的充填效果。为实现塑件的自动脱模,设计了3个脱模步骤,相应的机构及机构动作为采用了2副哈夫滑块机构用于塑件外壁的脱模,2副哈夫滑块机构均依靠模具打开的开模动力分次实施抽芯;第一副哈夫滑块机构用于定模一侧外壁的侧抽芯脱模,其通过动模侧的第一次开模打开驱动,完成先抽芯动作;第二副哈夫滑块机构用于动模一侧外壁圆环型凹槽的侧抽芯脱模,其通过动模侧的第二次开模打开驱动,完成抽芯动作。为实现模具2次开模按顺序进行,该模具中设计了一种开模控制机构,机构通过解锁插杆驱动移动锁芯实现与锁钩的锁闭/开锁功能,从而实现了模具开/闭模动作的有序进行。

圆弧抽芯注塑模具优化设计

基于圆弧抽芯注塑模具,根据塑件结构及材料性能特点,对浇口的位置及结构进行了优化设计,通过CAE模拟分析得到位于填充末端、最大壁厚处的塑件最大变形量为0.739 mm,变形量在设计允许范围内。以油缸作为驱动动力源,通过齿条驱动齿轮、内齿轮旋转,实现抽芯动作;将内齿轮设计为异形非标齿轮,减少了所占空间,实现了1模2腔布局。为解决圆弧型芯冷却水路难以加工的问题,设计的加工工序为先按照直型芯进行粗加工,钻孔加工型芯冷却水路,然后,将型芯加热弯曲为所需形状,并进行调质处理,最后对型芯进行精加工使其满足设计要求,达到了随形冷却效果。传动机构关键参数采用理论计算与CAE模拟分析相结合的法验证,测试结果表明,计算校核效率提高了约4倍。

小型电动汽车信号器外壳注射模设计

介绍了电动汽车信号器外壳的注射模设计。塑件成型材料选用科思创PC 2456,采用两板模进行成型。浇注系统中,使用2个扇形冷浇口对模腔进行浇注。塑件注塑工艺参数选定为,喷嘴出口料温为230~250℃;注射速度为200 mm/s;模具温度为80℃;注射时间为1~5 s,注射压力为80~100 MPa;保压时间为5~10 s,保压压力为40~60 MPa;背压为2~4 MPa;冷却时间为10~15 s。模具中,针对塑件外壁、内壁的脱模困难,设置了5个斜导柱滑块机构、1个3次抽芯复合机构、1个中抽式内收先抽芯滑块机构、3个斜顶机构、6个推管机构及多根顶针用于塑件的脱模。其中,3次抽芯复合滑块机构中,3个抽芯滑块组合在一起,先通过第一次开模驱动2个滑块联动抽芯,再通过第二次开模驱动3个滑块同步抽芯和移动,较为妥善地解决了塑件侧槽需二次抽芯脱模难题。模具机构选用恰当,紧凑合理,动作达标;与其它设计方案相比,制造成本约降低减少13%,工作效率约提高5%。

汽车空调管接头复杂塑件注塑模设计

为某汽车空调管接头复杂塑件的注射成型设计了一副两板式模具,解决了该塑件因结构复杂导致脱模困难、难以实现自动化注塑生产的实际问题。由于该塑件的圆柱壳主体上附加设置了90°弯管接口、斜置直管接口、法兰台直通管接口、直管+65°弯管接口等4个异型结构特征,导致塑件的脱模机构设计非常困难。为解决该问题,采用脱模方向集成分类法等设计方法将塑件的脱模机构按区域来设计,在定模一侧设计了6个定模滑块先抽芯机构用于90°弯管接口、斜置直管接口这两个特征的先抽芯脱模,6个机构的抽芯动作由定模侧增加的一侧开模打开进行机械式驱动完成定模先抽芯动作。在模具动模一侧设置了4个脱模机构,包括2个滑块机构、1个滑块+弯管复合机构和1个大尺寸推管机构。分别由斜导柱和油缸驱动2个滑块机构,用于法兰台直通管接口脱模。滑块+弯管复合机构用于直管+65°弯管接口特征的脱模,先由斜导柱驱动滑块完成直线抽芯,后由油缸驱动弯管型芯带动直线抽芯滑块一起移动,完成65°弯管特征的旋转抽芯脱模。最后,由大尺寸推管机构顶出而实现塑件的完全脱模。

冰箱零度室卡条注射模设计

通过分析冰箱零度室卡条的结构特征,介绍了塑件注射模的设计过程。通过前期分析,确定了“热流道+普通流道”的浇注系统,设计“滑块+斜推杆”侧向抽芯机构实现塑件外凹槽倒扣顺利脱模,滑块成型结构由大滑块和4个滑块镶件连接组合,由于滑块脱模行程较长,采用滑块座延长其行程,降低制造成本,斜推机构由斜推杆、斜推导向块和斜推座组成并留有3mm的安全距离。采用“推杆+斜推杆”联合推出,确保塑件在推出过程中受力均匀。实践证明:使用该注射模能成型完整、表面质量良好的合格塑件。