Indirect Tooling Research Articles

Characterizations of polymer injection molding tools with conformal cooling channels fabricated by direct and indirect rapid tooling technologies

Characterizations of polymer injection molding tools with conformal cooling channels fabricated by direct and indirect rapid tooling technologies

Copper Electroforming Optimization for Fused Deposition Modeling Produced ABS Components for Indirect Tooling Applications

The market trends from last few decades have increased the pressure on development of the new products in minimum time. This can be supplemented with modification in the manufacturing processes for product development. Since last two decades, additive manufacturing (AM) also known as rapid prototyping has been used to produce components. The present work aims at optimization of thickness of deposition and surface finish of copper on Acrylonitrile Butadiene Styrene (ABS) components produced by Fused Deposition Modeling (FDM), which can be used for indirect tooling. The different process parameters such as Voltage, Concentration of Copper sulfate Solution (CSS) and deposition time are optimized. The experiment reveals that the best process parameters for maximum deposition rate gives a deposition rate of 0.19 mm/h. The surface roughness is found to be minimum at the lower values of the process parameters as 1.87 [Formula: see text]m. It has been observed that voltage (43.2%) and concentration of CSS (48.8%) significantly affect the deposition rate and for surface finish the concentration of CSS (69.59%) is the major contributor. The microstructure study of the deposited copper reveals a variation in the grain size from coarse to fine as the thickness of the deposited layer increases.

Multi-metal additive manufacturing process chain for optical quality mold generation

Abstract This paper introduces an innovative process chain for the generation of mold elements based on multi-metal additive manufacturing. Starting from an indirect tooling approach for the fabrication of a mold master with optical surface quality, three different additive processes, namely electroforming, thermal spraying and selective laser melting (SLM), are combined to manufacture a test mold element. In order to maintain the targeted optical quality of the mold surface, SLM process parameters optimization has been carried out through numerical simulations. The approach is experimentally verified by generating prototype mold inserts and validated in injection molding trials, showing no signs of degradation of the mold insert after 1000 injection molding cycles.

Development and application of a conformal cooling channel with easy removal and smooth surfaces

The cooling time in an injection molding process comprises about 60 to 80% of the entire molding cycle. Throughput and molded part quality can be improved by the mold with conformal cooling channels. Injection molds or dies with conformal cooling channels have been developed by rapid tooling technology. However, the manufacturing process for the injection mold with conformal cooling channels made of ABS polymers is not environmentally friendly. In addition, the fabrication process for a wax cooling channel with complex geometrical shapes is very time-consuming. It was found that the wax filament fabricated by the mold made by indirect tooling has better quality. A method for fabricating long wax filament using the butt joint method was developed. The optimal process parameters for making the long wax filament by the butt joint method are the butt angle of 30°, wax temperature of 82 °C, and injection pressure of 0.6 kgf/cm2. The optimal process parameters for the surface quality improvement of wax cooling channels are the hot water temperature of 85 °C and the immersion time of 10 s. Finally, the rapid tooling technology was used to make the injection mold with a smooth surface.

Additive Manufacturing of Mould Inserts with Mirror-like Surfaces

Selective laser melting (SLM) is often applied in the production of steel moulds with high wear resistance and conformal cooling channels for advanced thermal management. The surface finishing of such moulds is crucial, especially if it is intended for the moulding of plastic parts with aesthetic functionality. The surface quality of such metal 3D printed moulds is typically refined by means of subsequent material removal processes, but this is often hindered by residual porosity and inhomogeneity in the metal structure of the 3D-printed part.In this paper an indirect tooling process chain for production of mould inserts is proposed. The process chain aims at exploiting the good replication capability of electroformed nickel, to copy mirror-like substrates. The bulky part of the insert is produced by means of SLM that shows a considerably higher material deposition rate. The thermal input is controlled throughout the process chain to prevent deleterious grains growth in the nickel layer.The roughness of the nickel surface is measured after the selective etching of the substrate and compared with the substrate roughness before the nickel deposition, showing good replication of the master surface. The proposed process chain overcomes the problems related to the deposition of thick electroformed coatings by coupling electroforming with higher output additive processes such as SLM - that furthermore allows the introduction of cooling channels in close contact with the mould surface.

Experimental investigations for dimensional accuracy and surface finish of polyurethane prototypes fabricated by indirect rapid tooling: a case study

In this research work, an effort has been made to study the influence of selected input parameters on the dimensional accuracy (linear as well as radial) and surface finish of polyurethane prototypes fabricated by vacuum casting (VC) process as a case study. The master pattern required for making a silicone mould has been fabricated by fused deposition modelling and its surface finish has been enhanced by chemical vapour smoothing process. Maximum shrinkage of 2.29 and 4.77% has been observed in the selected linear and radial dimension, respectively, after the VC process. Optimal parameter settings that were different for both the dimensions as well as surface finish have been obtained using Taguchi’s L18 orthogonal array. Finally, parameter setting that simultaneously minimizes the dimensional deviation and surface roughness has been found out using response optimization module of Minitab 17 software and the results obtained have been verified by performing the confirmation experiments. The tolerance grades for the selected dimension of the prototypes were found to be acceptable as per the ISO standard UNI EN 20286-I (1995) and DIN16901 for plastic materials. In addition, the C pk value greater than 1.3 indicated that the proposed process is highly capable. The surface finish and dimensional accuracy of prototypes are at par with the traditional moulding patterns, and hence, they can be used as end-products or plastic-based master patterns for investment casting applications.

Polyjet technology applications for rapid tooling

Polymer Jetting (PolyJet) has proved to be one of the most accurate additive manufacturing technologies, in order to manufacture rapid tools. Rapid Tooling (RT) is different from conventional tooling as follow: manufacturing time is shorter, the cost is much less, but the tool life is shorter and tolerances are wider. The purpose of this paper is to make a comparative study between the soft tools (silicon moulds) and hard tools (acrylic thermoplastic moulds) based on the Polymer Jetting technology. Thus, two types of moulds have been made in order to manufacture a test part. Reaction injection moulding (RIM) and casting techniques were used to fill these moulds with resins that simulate the plastic injection materials. Rapid tooling applications, such as indirect tooling and direct tooling, based on PolyJet technology were experimentally investigated.

Evaluation of service life of silicone rubber molds using vacuum casting

Shortening the time-to-market is an important issue in the manufacturing industry. Indirect tooling technology was regarded as a promising approach of reducing time and cost to the market in a new product development phase. Silicone rubber mold was frequently employed in the indirect tooling. In this study, the service life of silicone rubber molds was investigated using both wax injection molding and vacuum casting. The experimental results revealed that the average roughness of the inner surface of silicone rubber mold were increased with increasing the number of test runs and saturated after 25 test runs. The degassing time needs to be increased with increasing the number of test runs in the vacuum casting process. The criteria for judging the service life of silicone rubber molds include surface quality of the parts fabricated, whitening regions in the inner wall surfaces of silicone rubber molds, and the overall elasticity of silicone rubber molds.

Development of rapid tooling by rapid prototyping technology and electroless nickel plating for low-volume production of plastic parts

A rapid tooling approach is presented in this article to build an injection mould for low-volume production of plastic parts. This is an indirect tooling method using a rapid prototype model as a casting pattern. A layer of nickel–phosphorous alloy is plated on the casting pattern before it is cast in the aluminium-filled epoxy resin to form a cavity insert. After the removal of the casting pattern, the nickel–phosphorous alloy layer left on the wall of epoxy cavity insert acts as a protective layer to improve the tool life. The insert is installed in a mouldbase for injection moulding experiment. Three plastic parts are tried on the moulds built by this rapid tooling approach. This research has shown that manufacturing an indirect rapid tooling using electroless nickel plating for low-volume production of plastic injection mouldings is feasible for the rapid prototyping models. The cavity insert can be fabricated using commonly available low-cost materials within 48 h. More importantly, the tool life is longer under normal plastic processing conditions and quality mouldings are obtained.

Development of a Low-Cost Automatic Vacuum Degassing System for Rapid Tooling

Silicone rubber mold is frequently used in the indirect tooling. Automatic vacuum casting system is widely used to degas in the manufacturing of silicone rubber mold, but the cost of hardware is very expensive. A low-cost automatic vacuum degassing system is designed, build and test in this study. Optimized parameters for degassing process are investigated. The saving in the degassing time is about 23.4%.This system offers many advantages such as reducing human error of operator, reducing noise and air pollutions derived from the vacuum pump of the vacuum casting system.

Additive Tooling for Tube Hydroforming

The use of tube hydroforming in manufacturing is increasing in popularity, particularly in automotive applications where it offers numerous cost and well-recognized performance advantages over conventional stamping and welding processes. In this paper, the use of indirect Additive Tooling is explored in the creation of tool inserts to be used in the production of exhaust manifolds for the automotive industry. The principal focus of this research concerns the identification of operational issues arising from the exploitation of Additive Tooling, together with the suggestion of a number of techniques and solutions which may be applied to mitigate the problems inherent in the rapid manufacture of tube hydroforming tools.

Application of rapid tooling for the production of moulds suitable for autoclave forming of CFRP

PurposeThe purpose of this paper is to demonstrate the applicability of an indirect rapid tooling technique to the autoclave forming of carbon fibre reinforced plastic laminates.Design/methodology/approachA rapid prototyping machine was used to process a photo elastic resin to fabricate the pre‐moulds. Liquid particle‐filled epoxy resin was poured in the pre‐mould and cured in an oven. Real autoclave process conditions were then applied to the mould several times to assess the geometrical stability and the accuracy of the produced parts, measured using a laser 3D scanner.FindingsThis paper reports the procedures developed for the rapid manufacture of carbon fibre reinforced plastic components.Research limitations/implicationsThe method is applicable to components of small to medium dimensions (max 500 mm).Originality/valueThis is a pioneer attempt towards the rapid manufacturing of high performances composite components. It has been presented for patenting purposes (Gian Luca Monti, Ezequiel Poodts, Giangiacomo Minak, and Cristiano Fragassa. Pat. Pending Nr. PS2010A000026, 2010).

Rapid optical inspection of bubbles in the silicone rubber

Silicone rubber mold is frequently used in the indirect tooling of rapid tooling technology. Defect inspection of silicone rubber after degassing process using vacuum machine is usually evaluated by visual inspection. The drawbacks of this method include human error, time consuming and exhaustive. An optical inspection system for inspecting the bubbles in the silicone rubber is developed in this work. Bubbles in solid silicone rubber or liquid silicone rubber can be easily inspected with high accuracy in the millimeter range by studying the peak intensity distribution profile of He–Ne laser radiation passed through the silicone rubber.

Technical Development on Rapid Green Silicone Rubber Mold

Rapid tooling technology is regarded as an important approach of reducing the cost and time to market for new products. Silicone rubber mold is frequently employed in the indirect tooling. Based on green manufacturing, a green silicone rubber mold fabrication process is developed and implemented in this work. This method provided a new, simple and green manufacturing to produce silicone runner mold. The advantages of this method include high yields of the mold fabrication, reducing the cost in the mold fabrication and environmentally conscious manufacturing. The saving in the cost of silicone rubber mold fabrication is up to 35.66 %.

Technical Development on Large Size Silicone Rubber Mold

Rapid tooling technology is regarded as an important method of reducing the cost and time to market in a new product development process. Silicone rubber mold is frequently employed in the indirect tooling. Based on green manufacturing, an environment friendly process for making large size silicone rubber is developed and implemented in this work. This method provides a new, simple, and green manufacturing to produce large size silicone rubber mold without loss of dimensional accuracy, geometrical accuracy, and surface roughness. The advantages of this method include high yields of the mold fabrication, reducing the cost in the mold fabrication, and environmentally conscious manufacturing. The saving in the cost of the rapid tooling is up to 66.41%.

Electroforming: from Rocket Engines to Nanotweezers

Electroforming is a surprisingly versatile process which is being utilised for production of a number of very different metallic products. The two main reasons for the exploitation of electroforming are the remarkable replication accuracy and the ability to grow seamless metallic products. In this paper the most important types of electroforming processes are discussed, along with the expected properties of the deposits and the challenges associated with selected applications. A special attention will be given to the utilisation of electroforming in the FlexPAET project. Keywords: Electroforming, indirect tooling, internal stress, alloy plating, pulse plating, Thermal Stress, Re-crystallisation

Gas turbine blade manufacturing by use of epoxy resin tooling and silicone rubber molding techniques

PurposeConventional investment casting of turbine blades is a time consuming and expensive process due to the complications in wax injection steps and the complex shape of airfoil surfaces. By using rapid investment casting, a substantial improvement in the gas turbine blade manufacturing process can be expected. However, this process needs to be able to compete with conventional investment casting from a dimensional accuracy view of point. The purpose of this paper is to investigate the manufacture of gas turbine blades via two indirect rapid tooling (RT) technologies, namely epoxy (EP) resin tooling and silicon rubber molding.Design/methodology/approachThe second stage blade of a Ruston TA 1750 gas turbine (rated at 1.3 MW) was digitized by a coordinate measuring machine. The aluminum‐filled EP resin and silicon rubber molds were fabricated using StereoLithography master models. Several wax patterns were made by injection in the EP resin and silicone rubber molds. These wax patterns were utilized for ceramic shell fabrication and blade casting.FindingsDimensional inspection of cast blades showed that silicone rubber molding was not a suitable approach for production of blade wax patterns. The maximum deviation for the final cast blade made using the silicone rubber mold was +0.402 mm. The maximum deviation for the final cast blade made using the EP resin mold was lower at −0.282 mm. This showed that EP resin tooling could enable new cost‐effective solutions for small batch production of gas turbine blades.Practical implicationsThe research results presented will give efficient industrial approach and scientific insight of the gas turbine blade manufacturing by use of rapid technologies.Originality/valueThere are some general research works related to utilization of rapid technologies for manufacturing of gas turbine blade. However, this paper presents a unique procedure of integrated reverse engineering and RT technologies for rapid investment casting of gas turbine blade through presenting comprehensive comparison between two techniques from dimensional accuracy view of point.

Study of Intelligent Controller Based on FWN Oriented to Indirect Nonmetal Rapid Tooling

As one key technology of Rapid Tooling (RT), Indirect Nonmetal Rapid Tooling (INRT) has been used widely, so this paper analyzed the modeling process of INRT and concluded that the velocity of stirring and casting are key factors which affect products quality and production efficiency. In nature, just need to control the speeds of driving motors. In order to resolve problems of existing modeling equipments, such as strong dependency on operators experience and low control precision, this paper studied an intelligent controller model based on Fuzzy Wavelet Network (FWN) which integrated wavelet analysis and fuzzy neural network technologies. The structure and implementation algorithm of FWN are introduced in detail. After considering the advantages of Permanent Magnet Synchronous Motor (PMSM), the INRT equipments use it as driving motors. Because it is nonlinear, uncertain, coupled, sensitive and multivariable system, this paper made improvement on traditional IP controller, FWN acted as error compensator which can compensate for disturbance influence and trace expected speed in real time. The IP intelligent controller based on FWN can strengthen interference ability. The robustness of this control system has been verified by simulation experiment. This controller realized closed loop control of stirring and casting motor and improved the products quality and control precision of INRT.

Rapid tooling aided by reverse engineering to manufacture EDM electrodes

The present work deals with the application of indirect rapid tooling (RT) technology to manufacture electrical discharge machining (EDM) copper electrodes from investment casting, with wax prototypes made by ThermoJet 3D printing, a rapid prototyping (RP) technique. The reverse engineering (RE) method is utilised to transform the point cloud data of an object surface, obtained from 3D digitising, in a 3D CAD surface model dataset. The methodology presented is fundamental to verify the prototype’s geometry for tooling so as to assure its metrological accuracy and to optimise foundry process parameters using finite element analysis (FEA). Based on a case study, some functional conclusions are presented for the application of RT in manufacturing EDM electrodes aided by 3D digitising and RE, validating the accomplishment by the integration of these technologies and methodologies in EDM manufacturing processes.

Conversion of rapid prototyping models into metallic tools by ceramic moulding - an indirect rapid tooling process

INEGI developed a process to convert models made by rapid prototyping or conventional techniques into metallic moulds. The main purpose is to rapidly obtain prototype tools by casting a metal into a ceramic mould produced by mixing in variable proportions, ceramic particles, a liquid binder and a catalyst added to start a sol-gel reaction. This liquid slurry is poured into the box containing the mould to be reproduced. After a short period of time the ceramic mixture acquires a rubber consistency. The pattern is removed from the ceramic mould, which is fired and sintered in order to generate an inert mould with the desired strength in which most alloys can be cast. The effect of ceramic materials (shape, granulometric distribution, chemical composition), sintering conditions (time and temperature) and casting conditions (mould preheating temperature and pouring temperature) were studied in order to obtain ceramic moulds and, subsequently, metallic moulds with tailored properties (accuracy reproduction of details, low roughness and high mechanical strength).