Performance evaluation of conformal and straight cooling channels on injection moulded part

In injection moulding process, warpage is one of the main quality aspects measured for moulded parts while cycle time to produce a part indicates the efficiency of the process. Efficient cooling is a huge challenge to many mould designers for achieving a uniform thermal distribution in an injection mould where it affects both quality and productivity. The use of conformal cooling design has been reported as very effective to distribute thermal uniformly, thus able to improve part quality as well as reducing moulding cycle time. However, most of previous researchers only focused on simulation studies and they hardly performed experimental works to verify the simulation results. In this study, a Milled Groove Square Shape (MGSS) conformal cooling channel has been designed, simulated, fabricated and tested using a front panel housing as the case study. Performance evaluations on the MGSS conformal cooling channel and straight cooling channel were conducted using simulation and experimental works in terms of quality (warpage) and productivity (cycle time) of the moulded part. Mould and coolant input temperatures were varied in both evaluations, i.e. mould temperature (40 oC to 80 oC) and coolant temperature (25 oC to 65 oC). Results showed that the MGSS conformal cooling was superior with improved cycle time from 37.57% to 48.66% (simulation) and confirmed by experimental trials (27.89% to 36.15%). Simulated results showed that there is no warpage on the front panel housing in x direction for both types of cooling channels. However, experimental results indicated that warpage occurs in x direction in both cooling channel designs, but MGSS conformal cooling type demonstrates more reduction from 36.36% to 76%. Similarly, warpage in y direction recorded a remarkable improvement within the range of 34.3% to 41.5% and 16.7% to 35.48% respectively from the simulated and experimental results when employing the MGSS conformal cooling channel. The fabrication cost of the MGSS conformal cooling channel is approximately 3 % to 5 % higher which depends on the complexity of part shape as compared to the straight cooling channel. The finding shows that the MGSS conformal cooling channel design offers very encouraging results which is able to improve part quality as well as productivity at an acceptable manufacturing cost

Effect of spent coffee grounds and rice husk amount towards the swelling properties of hydrogel using graft polymerization

Hydrogels are widely known for their ability to absorb water without being dissolved. This characteristic, which is known as swelling has been studied by many researchers in various sectors such as medicine, pharmacy, agriculture, health science and many more. This paper presents a study on the swelling properties of hydrogel that was grafted with spent coffee grounds and rice husk ash. The hydrogel was prepared with acrylic acid as the monomer and acrylamide as the co-monomer. The hydrogel was grafted with spent coffee grounds and rice husk ash separately, with varied weight percent (wt%). The hydrogel was characterized using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The 0.1 (wt%) rice husk ash grafted hydrogel has the best swelling properties as shown by the highest water absorption, with the most porous structure and the highest crystalline temperature (122.0 °C). The FTIR wavenumber showed that the hydrogel is grafted properly as new wavenumbers are formed, whereas the TGA analysis shown that it had the highest decomposition temperature (658.6 °C)

A review on graft compatibilizer for thermoplastic elastomer blend

A biodegradable thermoplastic elastomer (TPE) blend is developed by blending poly (lactic acid) (PLA) and natural rubber (NR) or epoxidized natural rubber (ENR) and it is a sustainable substitution in recent years for synthetic polymers. PLA is high in mechanical strength and compostable, but it is highly stiff and brittle. The incorporation of NR or ENR to PLA increases the impact strength and toughness of PLA. However, the disparity in polarity between PLA and elastomer phase like NR and ENR results in TPE blend being incompatible. Hence, compatibilization is essential to improve its polarity and develop interactions. Compatibilizer that composed of two different polymer is known is graft compatibilizer with the aid of grafting agent. The graft compatibilizers are divided into two categories. The first type is made up of one polymer and grafting agent and, the other one is composed of two polymer groups and grafting agent. These two types of graft compatibilizer can be prepared via two different method such as direct melt blending and solution. Apart from this, the TPE blend is produced via the melt blending technique with mixing machines such as internal mixer and extruder. This article has reviewed the preparation of the graft compatibilizer and blending technique of TPE. Based on the findings, the graft compatibilizers has a significant role in improving miscibility and compatibility across blend composed of different phase

Microstructure and high temperature oxidation of modified ductile ni-resist alloy with higher manganese content

In this study, ductile Ni-resist with a minimum of 18 wt% nickel composition was modified. Up to 12 wt% manganese was added together with 10 wt% nickel to investigate the effects of the alloying elements on its microstructure, mechanical properties and isothermal oxidation behaviour. The results show a higher manganese composition on modified ductile Ni-resist with increased carbide formation, and a slightly decreased elevated temperature tensile strength. The addition of higher Mn [wt%] slightly increased the oxidation resistance. Three different oxide layers were observed on the modified ductile Ni-resist after 25 h hot corrosion at 765◦C

Mechanical and durability analysis of fly ash based geopolymer with various compositions for rigid pavement applications

Ordinary Portland cement (OPC) is a conventional material used to construct rigid pave�ment that emits large amounts of carbon dioxide (CO2 ) during its manufacturing process, which is bad for the environment. It is also claimed that OPC is susceptible to acid attack, which increases the maintenance cost of rigid pavement. Therefore, a fly ash based geopolymer is proposed as a material for rigid pavement application as it releases lesser amounts of CO2 during the synthesis process and has higher acid resistance compared to OPC. This current study optimizes the formulation to produce fly ash based geopolymer with the highest compressive strength. In addition, the durability of fly ash based geopolymer concrete and OPC concrete in an acidic environment is also determined and compared. The results show that the optimum value of sodium hydroxide concentration, the ratio of sodium silicate to sodium hydroxide, and the ratio of solid-to-liquid for fly ash based geopolymer are 10 M, 2.0, and 2.5, respectively, with a maximum compressive strength of 47 MPa. The results also highlight that the durability of fly ash based geopolymer is higher than that of OPC concrete, indicating that fly ash based geopolymer is a better material for rigid pavement applications, with a percentage of compressive strength loss of 7.38% to 21.94% for OPC concrete. This current study contributes to the field of knowledge by providing a reference for future development of fly ash based geopolymer for rigid pavement applications

Potential of industrial By-Products based geopolymer for rigid concrete pavement application

Rigid pavements are less expensive than flexible pavements and have a 20-year service life, making them more suitable for areas with weak subgrade soil and poor drainage. However, the use of rigid pavements comes at the expense of the environment. The production of cement has caused serious environmental problems, the most serious of which is the emission of carbon dioxide gas (CO2) into the atmosphere, causing natural greenhouse effect and global warming. Sustainable materials aid in the reduction of CO2 emissions as well as the use of natural raw materials in cement production. In the past few decades, significant progress has been made to develop alternative sustainable building materials (such as geopolymer cement/concrete) in order to control CO2 emissions. Numerous studies have found that geopolymer is comparable to ordinary Portland cement (OPC) in terms of strength and chemical resistance. However, only a few studies have been done on the usage of geopolymer as a rigid pavement. From the review that has been done, it can be concluded that, in addition to high strength, the requirements for rigid pavement concrete material should include fast setting time, good workability and high durability. The review emphasized that geopolymers have been proven to have excellent strength, durability and processability which fulfil the requirement for rigid pavement application. Finally, this review also introduces future research opportunities regarding the potential of geopolymers as an alternative to OPC for rigid pavements

Geopolymer Ceramic Application: A Review on Mix Design, Properties and Reinforcement Enhancement

Geopolymers have been intensively explored over the past several decades and consid‐ ered as green materials and may be synthesised from natural sources and wastes. Global attention has been generated by the use of kaolin and calcined kaolin in the production of ceramics, green cement, and concrete for the construction industry and composite materials. The previous findings on ceramic geopolymer mix design and factors affecting their suitability as green ceramics are re‐ viewed. It has been found that kaolin offers significant benefit for ceramic geopolymer applications, including excellent chemical resistance, good mechanical properties, and good thermal properties that allow it to sinter at a low temperature, 200 °C. The review showed that ceramic geopolymers can be made from kaolin with a low calcination temperature that have similar properties to those made from high calcined temperature. However, the choice of alkali activator and chemical com‐ position should be carefully investigated, especially under normal curing conditions, 27 °C. A com‐ prehensive review of the properties of kaolin ceramic geopolymers is also presented, including compressive strength, chemical composition, morphological, and phase analysis. This review also highlights recent findings on the range of sintering temperature in the ceramic geopolymer field which should be performed between 600 °C and 1200 °C. A brief understanding of kaolin geopolymers with a few types of reinforcement towards property enhancement were covered. To improve toughness, the role of zirconia was highlighted. The addition of zirconia between 10% and 40% in geopolymer materials promises better properties and the mechanism reaction is presented. Findings from the review should be used to identify potential strategies that could develop the performance of the kaolin ceramic geopolymers industry in the electronics industry, cement, and biomedical materials

A review on the potential of polylactic acid based thermoplastic elastomer as filament material for fused deposition modelling

Currently, a range of sectors are implementing three-dimensional (3D) printing, which is a part of additive manufacturing (AM) technology via the fused deposition modelling (FDM) approach. As of now, various filament materials are available in the market and have their limitations. Thermoplastic elastomer (TPE) blend as a filament material in 3D printing should be implemented to overcome the weakness of available filaments. TPE blend stands out due to its flexibility, thermoplastic-like processability, and renewability. Based on the findings, TPE blend filament can be made with polylactic acid (PLA) thermoplastic and elastomers such as natural rubber (NR) and epoxidized natural rubber (ENR). The TPE printed components will be flexible; tough with excellent thermal and mechanical properties. In this paper, the characteristics of TPE are being reviewed to show the potential of TPE material as filament

Strength and Durability of Sustainable Self-Consolidating Concrete with High Levels of Supplementary Cementitious Materials

Self-consolidating concrete (SCC) has been used extensively in the construction industry because of its advanced characteristics of a highly flowable mixture and the ability to be consolidated under its own weight. One of the main challenges is the high content of OPC used in the production process. This research focuses on developing sustainable, high-strength self-consolidating concrete (SCC) by incorporating high levels of supplementary cementitious materials. The overarching purpose of this study is to replace OPC partially by up to 71% by using fly ash, GGBS, and microsilica to produce high-strength and durable SCC. Two groups of mixtures were designed to replace OPC. The first group contained 14%, 23.4%, and 32.77% fly ash and 6.4% microsilica. The second group contained 32.77%, 46.81%, and 65.5% GGBS and 6.4% microsilica. The fresh properties were investigated using the slump, V-funnel, L-box, and J-ring tests. The hardened properties were assessed using a compressive strength test, while water permeability, water absorption, and rapid chloride penetration tests were used to evaluate the durability. The innovation of this experimental work was introducing SCC with an unconventional mixture that can achieve highly durable and high-strength concrete. The results showed the feasibility of SCC by incorporating high volumes of fly ash and GGBS without compromising compressive strength and durability

Irregular Shape Effect of Brass and Copper Filler on the Properties of Metal Epoxy Composite (MEC) for Rapid Tooling Application

Due to their low shrinkage and easy moldability, metal epoxy composites (MEC) are recognized as an alternative material that can be applied as hybrid mold inserts manufactured with rapid tooling (RT) technologies. Although many studies have been conducted on MEC or reinforced composite, research on the material properties, especially on thermal conductivity and compressive strength, that contribute to the overall mold insert performance and molded part quality are still lacking. The purpose of this research is to investigate the effect of the cooling efficiency using MEC materials. Thus, this research aims to appraise a new formulation of MEC materials as mold inserts by further improving the mold insert performance. The effects of the thermal, physical, and mechanical properties of MEC mold inserts were examined using particles of brass (EB), copper (EC), and a combination of brass + copper (EBC) in irregular shapes. These particles were weighed at percentages ranging from 10% to 60% when mixed with epoxy resin to produce specimens according to related ASTM standards. A microstructure analysis was made using a scanning electron microscope (SEM) to investigate brass and copper particle distribution. When filler composition was increased from 10% to 60%, the values of density (g/cm3), hardness (Hv), and thermal conductivity (W/mK) showed a linear upward trend, with the highest value occurring at the highest filler composition percentage. The addition of filler composition increased the compressive strength, with the highest average compressive strength value occurring between 20% and 30% filler composition. Compressive strength indicated a nonlinear uptrend and decreased with increasing composition by more than 30%. The maximum value of compressive strength for EB, EC, and EBC was within the range of 90–104 MPa, with EB having the highest value (104 MPa). The ANSYS simulation software was used to conduct a transient thermal analysis in order to evaluate the cooling performance of the mold inserts. EC outperformed the EB and EBC in terms of cooling efficiency based on the results of thermal transient analysis at high compressive strength and high thermal conductivity conditions