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.

Seamless Bra Cup Moulding of Fabric-Foam Laminated Materials

Seamless bra cup moulding is an important manufacturing technique for the apparel industry,and in particular,for bra production.Polyurethane(PU)foams and/or fabric-foam laminated sheets are moulded into a desirable cup shape in order to fit the three-dimensional(3D)breast contour.Such foam cups not only provide a wide range of designs combined with different levels of softness and support,but also reduce production costs with minimum cutting and sewing of seams.In this study,two selected PU foam and fabric materials typically used for bra cup moulding were examined.Their respective performance behaviour in relation to different moulding temperatures and time changes were recorded and analyzed.The results reveal that cup heights are greatly affected by the use of foam and/or fabric-foam laminated materials.High moulding temperatures and/or prolonged dwell time could be required when deforming laminated materials and setting large cup sizes.Nevertheless,cup height cannot be taken as the only criteria to determine the optimal moulding conditions,and this is especially the case for large cup sizes.The design of mould heads is a major factor that affects the dimension changes of foam cups.In this respect,to control the foam moulding process,it is suggested that bra manufacturers examine the fabric/foam material properties to determine the optimal moulding condition,and quantify the shape of foam cups to enhance the design and development process of aluminum mould heads.

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.

Development tendencies of moulding and core sands

Further development of the technology for making moulding and core sands will be strictly limited by tough requirements due to protection of the natural environment. These tendencies are becoming more and more tense, so that we will reach a point when even processes, that from technological point of view fulfill high requirements of the foundry industry, must be replaced by more ecologically-friendly solutions. Hence, technologies using synthetic resins as binding materials will be limited. This paper presents some predictable development tendencies of moulding and core sands. The increasing role of inorganic substances will be noticed, including silicate binders with significantly improved properties, such as improved knock-out property or higher reclamation strength. Other interesting solutions might also be moulding sands bonded by geo-polymers and phosphate binders or salts and also binders based on degradable biopolymers. These tendencies and the usefulness of these binders are put forward in this paper.

Semi-solid moulding:Competition to cast and machine from forging in making automotive complex components

The very latest technique for impeller manufacture is called semi-solid moulding(SSM).Cummins Turbo Technologies Limited,together with Aluminum Complex Components Inc,developed SSM compressor wheels as a way of achieving cost and durability performance somewhere between that of cast and machined from solid(MFS) aluminium alloy wheels.Experimental results show SSM material has a superior microstructure and mechanical properties over cast and comparable to MFS materials.Component testing including durability testing,using accelerated speed cycle tests,proves SSM compressor wheels emerge as being significantly more durable than cast equivalents and approaching that of MFS impellers.Further challenges for semi-solid processing in manufacture of other complex components and other materials in automotive industry in terms of both cost and durability are also discussed.

A new numerical simulation model for high pressure squeezing moulding

High pressure squeeze is the most popular moulding process applied in modern moulding machines.Because of the unique characters of moulding sand and nonlinearity of squeezing process,the mechanical model is of key importance for computer simulation.Drucker-Prager/Cap is a typical soil mechanical theory model and it was used to simulate the squeezing process in this study,while ABAQUS software is used to simulate dynamic stress/strain evolution during the process.The simulation agrees well with the experimental results.We conclude that Drucker-Prager/Cap is an appropriate model for the squeezing compaction of moulding sand,and that the associated nonlinearity can be solved well with ABAQUS software.

Influence of wet activation of used inorganic binder on cyclically refreshed water glass moulding sands hardened by microwaves

The paper presents the research results of using an innovative method to reclaim the waste moulding sands containing water glass. Two of the examined processes are connected with "dry" or "wet" activation of inorganic binder in waste moulding sand mixtures physically hardened by microwave radiation. The sand mixtures consisting of high-silica sand and water-glass with average molar module 2.5, were subjected to the following cyclical process: mixing the components, compacting, microwave heating, cooling-down, thermally loading the mould to 800 °C, cooling-down to ambient temperature, and knocking-out. After being knocked-out, the waste moulding sands were subjected to either dry or wet activation of the binder. To activate thermally treated inorganic binder, each of the examined processes employed the surface phenomenon usually associated to mechanical reclamation. The study also covered possible use of some elements of wet reclamation to rehydrate waste binder. To evaluate the effectiveness of the two proposed methods of waste binder activation, selected strength and technological parameters were measured. After each subsequent processing cycle, the permeability, tensile strength and bending strength were determined. In addition, the surface of activated sand grains was examined with a scanning electron microscope. Analysis of the results indicates that it is possible to re-activate the used binder such as sodium silicate, and to stabilize the strength parameters in both activation processes. Permeability of the refreshed moulding sands strongly depends on the surface condition of high-silica grains. The wet activation process by wetting and buffering knocked-out moulding sands in closed humid environment makes it possible to reduce the content of refreshing additive in water-glass. The moulding sands cyclically prepared in both processes do not require the addition of fresh high-silica sand. The relatively high quality achieved in the refreshed moulding sands allows them to be reused for manufacture of next moulds. Thus, the two proposed methods for cyclically processing used moulding sands containing sodium silicate, subject to microwave hardening, are suitable for economic and ecological circulation moulding mixtures.

High-quality manufacturing method ofcomplicated castings based on multi-materialhybrid moulding process

A multi-material hybrid patternless moulding process for complicated castings has been proposed. Moulding sands used in the hybrid moulding process include silica sand, ceramic sand, chromite sand, zircon sand, and steel shot sand. Experimental method was used to study the effects of moulding sands on the temperature field, mechanical properties, and dimensional precision of the iron castings. Under the condition that the wall thickness on different sides of the casting is the same, when the wall thickness is greater than 10 mm, the heat storage capacity of the moulding sands from strong to weak is steel shot sand, zircon sand, chromite sand, ceramic foundry sand, and silica sand. Tensile strength of the obtained castings from high to low is zircon sand, chromite sand, steel shot sand, ceramic sand, and silica sand. Contraction rate of the obtained castings from high to low is steel shot sand, zircon sand, chromite sand, silica sand, and ceramic sand. Therefore, steel shot sand and zircon sand can be used as chilled sand, and even can be used instead of cold iron when the casting wall thickness is greater than 10 mm. Zircon sand and chromite sand can be used to obtain high mechanical properties, and silica sand and ceramic sand can be selected to obtain high dimensional precision of the castings. Finally, a typical iron casting piece was tested by experiment using the hybrid moulding process. Excellent performances of iron castings confirm the feasibility of the hybrid moulding process.

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.

Processability of Biobased Thermoset Resins and Flax Fibres Reinforcements Using Vacuum Assisted Resin Transfer Moulding

Biocomposite panels consisting of biobased thermoset resins (EP, PU, UP, and tannin) and flax fibre reinforcements were produced using the vacuum assisted resin transfer moulding process. Panels based on a conventional chemical-based resin matrix were also produced, and investigated comparatively. Rheometric analyses were performed to evaluate the suitability of these resins for liquid composite moulding. Tensile, shear, and impactbending tests have been carried out to assess the quality and mechanical performance of manufactured laminates. The impregnation quality was assessed by means of ultrasonic-C-scanning and microscopy. It turned out that the properties of the biobased composite panels made of biobased epoxy resin and a biobased UP-resin from the company Nuplex in New Zealand were onlay slightly inferior to those produced with a conventional epoxy resin. A biobased PU-resin from the company USSC in the USA developed voids during curing. A tannin-based resin containing of formaldehyde was not processable.

Correlation between Chemical Glass Components and the Glass Sticking on Sputtered PtIr Physical Vapour Deposition Coatings for Precision Blank Moulding

The increasing demand on high quality optical systems with complex geometries, low tolerances and a low installation space necessitates new replicative production systems for complex optical glass elements. The technology precision blank moulding shows promising properties to comply with these demands on an industrial bulk production. Due to the required high surface quality and low surface roughness of produced optical elements, moulding dies must have comparable low roughness and defect-free surfaces. To reduce wear and chemical interaction with the hot glass, moulding dies are often coated with a thin sputtered physical vapour deposition (PVD) coating. The objective of this research work was to analyze the diffusion behaviour inside different industrially used low-Tg (transformation point) glasses and their interaction with three different noble metal coating systems during an application oriented heating test. Therefore, three different PtIr coating systems with different interlayers (50 nm nickel as reference, 20 nm chromium, without interlayer) were deposited and tested in combination with six different industrially used low-Tg glasses. Using energy-dispersive X-ray spectroscopy (EDS) a diffusion of the light alkali and alkaline earth metals (sodium, potassium, calcium) was detected. The interaction between glass and coating was analyzed by EDS, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The different chemical compositions of the glasses have a significant influence on the interaction between glass and coating system. Several correlations between the chemical composition of the glasses and the amount of glass adhesion on the three coating systems were identified. The percentage of ions allocated to network modifiers lithium oxide, sodium oxide and potassium oxide correlates with the intensity of the interaction between coating and glass. The intensity of glass adhesion on the reference coating system PtIr/Ni is related with the zinc content in the glasses. Due to a diffusion process of the nickel interlayer, a direct correlation between the zinc content in the glasses and glass adhesion exists. The coating system with chromium interlayer showed comparable results to the system without interlayer.

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.

Investigations of physicochemical properties of dusts generated in mechanical reclamation process of spent moulding sands with alkaline resins

Mechanical reclamation processes of spent moulding sands generate large amounts of postreclamation dusts mainly containing rubbed spent binding agents and quartz dusts. The amount of postreclamation dusts, depending in the reclamation system effi ciency and the reclaim dedusting system, can reach 5%-10% in relation to the total reclaimed spent moulding sand. The proper utilization of such material is a big problem facing foundries these days. This study presents the results of investigations of physicochemical properties of post- reclamation dusts. All tested dusts originated from various Polish cast steel plants applying the mechanical reclamation process of moulding sands with alkaline resins, obtained from different producers. Different dusts, delivered from foundries, were tested to determine their chemical composition, granular characterization, physicochemical and energetic properties. Presented results confi rmed assumptions that it is possible to utilize dusts generated during mechanical reclamation of used sands with organic resins as a source of energy.

Biodegradable materials as binders for IVth generation moulding sands

This paper focuses on the possibility of using the biodegradable materials as binders(or parts of binders' compositions) for foundry moulding and core sands. Results showed that there is a great possibility of using available biodegradable materials as foundry moulding sand binders. Using biodegradable materials as partial content of new binders, or additives to moulding sands may not only decrease the toxicity and increase reclamation ability of tested moulding sands, but also accelerate the biodegradation rate of used binders, and the new biodegradable additive(PCL) did not decrease the strength and thermal properties. In addition, using polycaprolactone(PCL) as a biodegradable material may improve the flexibility of moulding sands with polymeric binder and reduce toxicity.

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.

Conversion of Rapid Prototyping Models into Metallic Tools by Ceramic Moulding—an Indirect Rapid Tooling Process

A process to convert models made by rapid prototypi ng techniques like SL (stereolitography) and LOM (laminated object manufacturing) or by conventional techniques (silicones, resins, wax, etc.) into metallic mould s or tools has been developed. The main purpose of this technique is to rapidly obtain the first prototypes of parts, for plastics injection, forging or any oth er manufacturing process using the tools produced by casting a metal into a cera mic mould. Briefly, it can be said that the ceramic moulds are produced by mixing in variab le proportions, depending on the type of ceramics employed, strength and roughne ss desired, a ceramic mixture composed by alumina and/or zirconium silicates bon ded with silica coming from a liquid binder, based on ethyl silicate. A catalyst is added to the slurry in order to produce a sol-gel reaction. The liquid slur ry is poured into the box containing the mould to be reproduced. After a short p eriod of time, controlled by the amount of gelling agent, the ceramic mixture ac quires a rubber consistency. The pattern is removed from the ceramic mould, whic h is fired to stop the gelation reaction. After this stabilization the ceramic m ould is sintered at high temperatures in order to generate an inert mould wi th the desired strength in which almost all metallic alloys can be cast. The effect of ceramic materials (shape, granulometric distribution, chemical com position, etc.), processing parameters (proportion binder/ceramic/catalyst, sint ering conditions, etc.) and casting conditions (mould pre-heating temperature a nd pouring temperature) were studied in order to obtain metallic moulds or tools with tailored properties (high dimensional accuracy, low roughness and high mec hanical strength).

Effect of Varying Corn Cob and Rice Husk Ashes on Properties of Moulding Sand

The use of rice husk and corn cob ashes as aggregates for foundry moulding sand has been studied. 5-12.5 weight percent of rice husk and corn cob ashes were added to the sand mixture and the sand properties determined. A mixture of equal proportion of rice husk and corn cob ashes was also used. In each case, four weight percent water and clay were added to the sand mixture. Some of the properties of the sand tested are: permeability, green compression strength, dry compression strength, green shear strength, dry shear strength, moisture content and permeability. The results showed that the green compression strength, green shear strength, moisture content and permeability decrease with increase in the additives (rice husk ash, corn cob ash, and (50% rice husk and 50% corn cob ashes). While dry compression strength and dry shear strength increase with increase in weight percent of the additives.

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.

Impact of Swelling Indices of Sokoto Clays on the Moulding Properties of the Clays in Sand Mixtures

The Impact of Swelling Indices of Sokoto Clays on the Moulding Properties of the Clays in Sand Mixtures was investi- gated. Four clays (labeled A, B, C, D) from different locations in Sokoto state of Nigeria were sampled. The sampling method was that for each deposit five samples were taken at different positions and then mixed together. At the labora- tory they were washed to remove organic matter and then dried at 110°C in the oven. A laboratory ball mill was used to grind the dried clays. Each of the clay was then sampled for the determination of its swelling index. The determination of the moulding properties of the clays then followed. Only green compression strength, dry compression strength and green permeability, moulding properties were determined. The analysis of the result revealed that clay B has the highest green and dry strength values it had the highest green compression strength of 71.7 KN/m2 and the highest dry com- pression strength of 3225.75 KN/m2. Clay B also has the highest swelling index of 60% and very high degree of expan- siveness when compared to the other three clays. Clay B was followed by clay A with swelling index of 25%;the clay has high green and dry compression strength and a moderate degree of expansiveness. The inability of clay D with swelling index of 40% to be the next clay to clay B which has the highest swelling index of 60% among the four clays in terms of good moulding properties is an indication that high swelling index does not always mean good moulding properties in clay binders.