A plastic plate with surface micro features was injection molded to investigate the effect of pressure rise of melt on the replication of the micro structures. Prism pattern, which is used in many optical applications...A plastic plate with surface micro features was injection molded to investigate the effect of pressure rise of melt on the replication of the micro structures. Prism pattern, which is used in many optical applications, was selected as a model pattern. The prism pattern is 50 μm in pitch and 108° in the vertical angle. The overall size of the plate was 335 minx213 mm and the thickness of the plate varied linearly from 2.6 mm to 0.7 ram. The prism pattern was firstly machined on the nickel plated core block using micro diamond tool and this machined pattern core was installed in a mold for injection molding of prism patterned plate. Polymethyl methacrylate （PMMA） was used as a molding material. The pressure and temperature of the melt in the cavity were measured at different positions in the cavity and the replication of the pattern was also measured at the same positions. The results show that the pressure or temperature profile through the process depends on the shape and the size of the plate. The replication is affected by the temperature and pressure profiles at the early stage of filling, which is right after the melt reaches the position to be measured.展开更多
In order to reduce the "trial-mold" risk and cost,numerical simulation method was applied to micro injection molding weld line development investigation. The micro tensile specimen which has the size of 0.1 ...In order to reduce the "trial-mold" risk and cost,numerical simulation method was applied to micro injection molding weld line development investigation. The micro tensile specimen which has the size of 0.1 mm(depth) ×0.4 mm(width) ×12 mm(length) in test area was selected as the objective part,and polypropylene(PP) as the experimental material. Respectively with specific commercial software(Mold Flow) and general computational fluid dynamic(CFD) software(Comsol Multiphysics) ,the simulation experiments for development of weld line in micro injection molding process were executed and the real comparison experiments were also carried out. The results show that during micro injection molding process,the specific commercial software for normal injection molding process is not valid to describe the micro flow process,the shape of flow front in micro cavity flowing which is important in weld line developing study and the contact angle due to surface tension are not able to be simulated. In order to improve the simulation results for micro weld line development,the general CFD software,which is more flexible in user defining function,is applied. The results show better effects in describing micro fluid flow behavior. As a conclusion,as for weld line forming process,the numerical simulation method can give a characteristic analysis results for processing parameters optimizing in micro injection molding process;but for both kinds of softwares quantitative analysis cannot be obtained unless the boundary condition and micro fluid mathematic model are improved in the future.展开更多
Micro powder injection molding （μPIM） was investigated for possible mass production of micro-components at rela- tively low cost. However, scaling down to such a level produces challenges in injection molding and d...Micro powder injection molding （μPIM） was investigated for possible mass production of micro-components at rela- tively low cost. However, scaling down to such a level produces challenges in injection molding and debinding. Micro gears were fabricated by μPIM from in-house feedstock. The effect of injection speed and injection pressure on the replication of the micro gear cavity was investigated. Solvent debinding and thermal debinding processes were discussed. The results show that micro gears can be successfully fabricated under the injection pressure of 70 MPa and the 60% injection speed. Either too low or too high injection speed can cause incomplete filling of micro gears. The same is the case with too low injection pressure. Too high injection pressure can bring cracks. Solvent debinding of micro gears was performed in a mixture of petroleum ether and ethanol. Subsequently, micro gears were successfully debound by a multistep heating schedule.展开更多
In the micro-molding of component with a micro-sized channel, the ability for polymer melt to flowing into the micro-channel in a macro-sized part is a big challenge. The multidimensional flow behaviors are included i...In the micro-molding of component with a micro-sized channel, the ability for polymer melt to flowing into the micro-channel in a macro-sized part is a big challenge. The multidimensional flow behaviors are included in the injection molding the macro-component with a micro-channel. In this case, a simplified model is used to analyze the flow behaviors of the macro-sized part within a micro-channel. The flow behaviors in the macro-cavity are estimated by using the finite element and finite difference methods. The influence of the injection rate, micro-channel size, heat transfer coefficient, and mold temperature on the flowing distance is investigated based on the non-isothermal analytic method. The results show that an increase in the radius of the micro-channel and mold temperature can improve effectively the flowing distance in the micro-channel.展开更多
A medical device of micro-jet injection for drug delivery is described in this paper. The device is powered by a Lorentz force driver (or voice coil motor, VCM) and is able to perform pulsed injection through controll...A medical device of micro-jet injection for drug delivery is described in this paper. The device is powered by a Lorentz force driver (or voice coil motor, VCM) and is able to perform pulsed injection through controlling the direction of the current passing through the device. The driving force and the resulting injection pressure are also controllable through control of the current intensity of the VCM. A physical model was established by combining the existing jet injection model with the relationship of the driving force obtained from a finite-element-method (FEM) analysis, and was verified by experimental measurements. The numerical calculation of the physical model reveals the relationship between the injection pressure and the current intensity of VCM under system conditions. In normal cases, the injection dose can be varied. Thus the relationship between the current intensity of VCM and the dose value was numerically obtained under the condition for the maximum injection pressure to be above a threshold value. These results can be used for optimization of the device.展开更多
基金Project supported by Development of Large Surface Micro-Machining System Technology of Ministry of Knowledge Economy, Korea
文摘A plastic plate with surface micro features was injection molded to investigate the effect of pressure rise of melt on the replication of the micro structures. Prism pattern, which is used in many optical applications, was selected as a model pattern. The prism pattern is 50 μm in pitch and 108° in the vertical angle. The overall size of the plate was 335 minx213 mm and the thickness of the plate varied linearly from 2.6 mm to 0.7 ram. The prism pattern was firstly machined on the nickel plated core block using micro diamond tool and this machined pattern core was installed in a mold for injection molding of prism patterned plate. Polymethyl methacrylate （PMMA） was used as a molding material. The pressure and temperature of the melt in the cavity were measured at different positions in the cavity and the replication of the pattern was also measured at the same positions. The results show that the pressure or temperature profile through the process depends on the shape and the size of the plate. The replication is affected by the temperature and pressure profiles at the early stage of filling, which is right after the melt reaches the position to be measured.
基金Project(ZI648/13-1) supported by German Research FoundationProject(D/06/00373) supported by German Academic Exchange Service
文摘In order to reduce the "trial-mold" risk and cost,numerical simulation method was applied to micro injection molding weld line development investigation. The micro tensile specimen which has the size of 0.1 mm(depth) ×0.4 mm(width) ×12 mm(length) in test area was selected as the objective part,and polypropylene(PP) as the experimental material. Respectively with specific commercial software(Mold Flow) and general computational fluid dynamic(CFD) software(Comsol Multiphysics) ,the simulation experiments for development of weld line in micro injection molding process were executed and the real comparison experiments were also carried out. The results show that during micro injection molding process,the specific commercial software for normal injection molding process is not valid to describe the micro flow process,the shape of flow front in micro cavity flowing which is important in weld line developing study and the contact angle due to surface tension are not able to be simulated. In order to improve the simulation results for micro weld line development,the general CFD software,which is more flexible in user defining function,is applied. The results show better effects in describing micro fluid flow behavior. As a conclusion,as for weld line forming process,the numerical simulation method can give a characteristic analysis results for processing parameters optimizing in micro injection molding process;but for both kinds of softwares quantitative analysis cannot be obtained unless the boundary condition and micro fluid mathematic model are improved in the future.
基金supported by the National Natural Science Foundation of China (No. 51172018)the Fok Ying Tong Education Foundation (No.122016)
文摘Micro powder injection molding （μPIM） was investigated for possible mass production of micro-components at rela- tively low cost. However, scaling down to such a level produces challenges in injection molding and debinding. Micro gears were fabricated by μPIM from in-house feedstock. The effect of injection speed and injection pressure on the replication of the micro gear cavity was investigated. Solvent debinding and thermal debinding processes were discussed. The results show that micro gears can be successfully fabricated under the injection pressure of 70 MPa and the 60% injection speed. Either too low or too high injection speed can cause incomplete filling of micro gears. The same is the case with too low injection pressure. Too high injection pressure can bring cracks. Solvent debinding of micro gears was performed in a mixture of petroleum ether and ethanol. Subsequently, micro gears were successfully debound by a multistep heating schedule.
基金Project supported by the National Natural Science Foundation of China(Nos.51303027 and 11172271)the Scientific Research Staring Foundation,Fujian University of Technology of China(No.GY-Z13028)+1 种基金the Research Fund of Fujian Education Department(No.JA11189)the Research Fund for Enterprise Technology Innovation(No.2011-702-04)
文摘In the micro-molding of component with a micro-sized channel, the ability for polymer melt to flowing into the micro-channel in a macro-sized part is a big challenge. The multidimensional flow behaviors are included in the injection molding the macro-component with a micro-channel. In this case, a simplified model is used to analyze the flow behaviors of the macro-sized part within a micro-channel. The flow behaviors in the macro-cavity are estimated by using the finite element and finite difference methods. The influence of the injection rate, micro-channel size, heat transfer coefficient, and mold temperature on the flowing distance is investigated based on the non-isothermal analytic method. The results show that an increase in the radius of the micro-channel and mold temperature can improve effectively the flowing distance in the micro-channel.
文摘A medical device of micro-jet injection for drug delivery is described in this paper. The device is powered by a Lorentz force driver (or voice coil motor, VCM) and is able to perform pulsed injection through controlling the direction of the current passing through the device. The driving force and the resulting injection pressure are also controllable through control of the current intensity of the VCM. A physical model was established by combining the existing jet injection model with the relationship of the driving force obtained from a finite-element-method (FEM) analysis, and was verified by experimental measurements. The numerical calculation of the physical model reveals the relationship between the injection pressure and the current intensity of VCM under system conditions. In normal cases, the injection dose can be varied. Thus the relationship between the current intensity of VCM and the dose value was numerically obtained under the condition for the maximum injection pressure to be above a threshold value. These results can be used for optimization of the device.
