A Practical Numerical Approach to Characterizing Non-Linear Shrinkage and Optimizing Dimensional Deviation of Injection-Molded Small Module Plastic Gears

He, Xiang; Wu, Wangqing

doi:10.3390/polym13132092

Cited by 13 publications

(12 citation statements)

References 51 publications

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“…The latter reflects lessening and uniformization of the volumetric shrinkage ( Figure 16 ), due to the reduction of the part thickness. This observation corroborates the results reported by several authors [ 8 , 11 , 28 , 29 ], which reported that shrinkage reduction and uniformization lead to the development of lower residual stresses. Moreover, by decreasing the residual stresses by half, superior performance of the FH parts should be expected under dynamic loading when in service.…”

Section: Resultssupporting

confidence: 93%

Computer-Aided Reengineering towards Plastic Part Failure Minimization

et al. 2021

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The work reported here intends to identify and mitigate the causes for failure in a plastic faucet holder, a part of an integral float faucet with a well-documented history of fracture occurrence. A methodology for the identification of hidden internal defects in plastic parts and the elaboration of the required corrective actions towards quality improvement is, therefore, presented. Firstly, part defects were identified via injection moulding process numerical simulation. The latter has enabled the prediction of an excessive volumetric shrinkage at the core of the faucet holder, highlighting the presence of internal voids and, hence, the possible deterioration of the load-bearing capacity. The supposition was later confirmed by X-ray topography scans. Part reengineering, consisting of localized thickness reduction, was the option chosen for decreasing the high shrinkage at the core. For validation purposes, structural analyses were carried out, with and without accounting for the injection moulding processing history. The results obtained during part structural analysis have enabled us to conclude that, when taking into account the residual stresses generated during injection moulding, the analysis more closely reflects the experimental data and allows us to implicitly envisage the propensity to fracture. Moreover, the part modifications, undertaken during the faucet holder reengineering, led to the reduction of the cumulative (processing and imposed by load) stresses by 50%, when compared to the original design analysed.

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Section: Resultssupporting

confidence: 93%

Computer-Aided Reengineering towards Plastic Part Failure Minimization

et al. 2021

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“…[ 1 , 2 , 3 , 4 ]. These polymer gears can be produced by classical cutting processes or, for large series production, by injection moulding [ 5 , 6 ]. Some of the main benefits of polymer gears are high size-weight ratio, low coefficient of friction, self-lubrication, high resistance against impact loading, ability to absorb and damp vibration, reduced noise, ability to be used in food preparation areas, etc.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of the Wear Behaviour of Coated Polymer Gears

et al. 2021

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A comprehensive experimental investigation of the wear behaviour of coated spur polymer gears made of POM is performed in this study. The three physical vapour deposition (PVD) coatings investigated were aluminium (Al), chromium (Cr), and chromium nitrite (CrN). Al was deposited in three process steps: By plasma activation, metallisation of Al by the magnetron sputtering process, and by plasma polymerisation. Cr deposition was performed in only one step, namely, the metallization of Cr by the magnetron sputtering process. The deposition of CrN was carried out in two steps: the first involved the metallization of Cr by the magnetron sputtering process while the second step, vapour deposition, involved the reactive metallisation of Cr with nitrogen, also by the magnetron sputtering process. The gears were tested on an in-house developed testing rig for different torques (16, 20, 24 and 30 Nm) and rotational speed of 1000 rpm. The duration of the experiments was set to 13 h, when the tooth thickness, and, consequently, the wear of the tooth flank was recorded. The experimental results showed that the influence of metallisation with aluminium, chromium, and chromium nitrite surface coatings on the wear behaviour of the analysed polymer gear is not significant. This is probably due to the fact that the analysed coatings were, in all cases, very thin (less than 500 nm), and therefore did not influence the wear resistance significantly. In that respect, an additional testing using thicker coatings should be applied in the further research work.

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“…The dimensions are also displayed in Figure 2b. These parameters position the produced gears in the class of small module gears, which have smaller specific surface area and smaller convection and radiation heat dissipation resistance during cooling compared to typical module gears [28]. As with other manufacturing methods, where many process parameters influence the geometric quality of products [29][30][31][32], numerous factors influence the geometric deviations during plastic gear injection moulding, namely the employed processing equipment, material properties, mould structure, part shape, and injection moulding process parameters [33,34].…”

Section: Polymer Gear Manufacturingmentioning

confidence: 99%

Comprehensive Areal Geometric Quality Characterisation of Injection Moulded Thermoplastic Gears

et al. 2022

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Injection moulding is currently the most widely employed production method for polymer gears. Current standardised gear metrology methods, which are based on metal gear inspection procedures, do not provide the key information regarding the geometric stability of injection moulded gears and are insufficient for a thorough gear inspection. The study developed novel areal quality parameters, along with a so-called moulding runout quality parameter, with a focus on the injection moulding method. The developed parameters were validated on twenty-nine gear samples, produced in the same moulding tool using various processing parameters. The gears were measured using a high-precision structured-light 3D scanner. The influence of injection moulding process parameters on the introduced novel quality parameters was investigated. The developed moulding runout quality parameter proved to be effective in evaluating the shrinkage that can occur in the injection moulding process. The novel moulding runout parameter returned an average value of −21.8 μm in comparison to 29.4 μm exhibited by the standard parameter on all the gears, where the negative value points directly to mould shrinkages. The rate of cooling was determined to be the most influential factor for the shrinkage of the gear. The developed areal parameters demonstrated to be advantageous in characterising the deviations on the teeth more comprehensively.

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A Practical Numerical Approach to Characterizing Non-Linear Shrinkage and Optimizing Dimensional Deviation of Injection-Molded Small Module Plastic Gears

Cited by 13 publications

References 51 publications

Computer-Aided Reengineering towards Plastic Part Failure Minimization

Computer-Aided Reengineering towards Plastic Part Failure Minimization

Experimental Investigation of the Wear Behaviour of Coated Polymer Gears

Comprehensive Areal Geometric Quality Characterisation of Injection Moulded Thermoplastic Gears

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