scholarly journals Categorization of Failures in Polymer Rapid Tools Used for Injection Molding

Processes ◽  
2019 ◽  
Vol 7 (1) ◽  
pp. 17 ◽  
Author(s):  
Anurag Bagalkot ◽  
Dirk Pons ◽  
Digby Symons ◽  
Don Clucas
Keyword(s):  
Injection Molding ◽  
Tool Life ◽  
Failure Modes ◽  
Shear Failure ◽  
Cost Effective ◽  
Critical Parameters ◽  
Cost Effective Method ◽  
Edge Failure ◽  
Underlying Mechanisms ◽  
Bending Failure

Background—Polymer rapid tooling (PRT) inserts for injection molding (IM) are a cost-effective method for prototyping and low-volume manufacturing. However, PRT inserts lack the robustness of steel inserts, leading to progressive deterioration and failure. This causes quality issues and reduced part numbers. Approach—Case studies were performed on PRT inserts, and different failures were observed over the life of the tool. Parts molded from the tool were examined to further understand the failures, and root causes were identified. Findings—Critical parameters affecting the tool life, and the effect of these parameters on different areas of tool are identified. A categorization of the different failure modes and the underlying mechanisms are presented. The main failure modes are: surface deterioration; surface scalding; avulsion; shear failure; bending failure; edge failure. The failure modes influence each other, and they may be connected in cascade sequences. Originality—The original contributions of this work are the identification of the failure modes and their relationships with the root causes. Suggestions are given for prolonging tool life via design practices and molding parameters.

scholarly journals Analysis of Raised Feature Failures on 3D Printed Injection Moulds

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1541
Author(s):  
Anurag Bagalkot ◽  
Dirk Pons ◽  
Digby Symons ◽  
Don Clucas
Keyword(s):  
Tool Life ◽  
Shear Failure ◽  
Flow Simulation ◽  
Tool Material ◽  
Cost Effective ◽  
Temperature Fields ◽  
Cost Effective Method ◽  
3D Printed ◽  
Shear Failures ◽  
Injection Pressures

Background: Polymer-based 3D Printed Injection Mould (3DIM) inserts are used as a cost-effective method for low volume injection moulding (50–500 parts). However, abrupt failure leading to a short tool life is a common shortcoming of 3DIM. Need: The underlying causes of raised feature failures on 3DIM are not well known. Failure is commonly attributed to bending or shearing of raised features on the tool. Understanding the causes may help in delaying the failure and increasing tool life. Approach: Tool failure was analysed from a first-principles perspective, using pressure and temperature fields as determined by mould flow simulation. Experimental results were also obtained for two types of tool material (Visijet M3-X and Digital ABS) with polycarbonate (Lexan 943A) as the part material. Findings: Results find against the idea that pin failure in 3DIM tools is caused by bending and shear failures induced by injection pressures. We also conclude that failure of raised features is not necessarily an abrupt failure as mentioned in the literature. Originality: The generally accepted explanation for the failure of raised features in 3DIM tooling is that injection pressures cause bending and shear failure. This paper disconfirms this notion on theoretical and experimental grounds.

Experimental Research on Four-Tube Concrete-Filled Steel Tubular Laced Columns

2011 ◽  
Vol 311-313 ◽  
pp. 2204-2207 ◽  
Author(s):  
Bo Wang Chen ◽  
Ran He ◽  
Jian Guo Tan ◽  
Yang Oyang
Keyword(s):  
Mechanical Properties ◽  
Yield Point ◽  
Experimental Research ◽  
Failure Modes ◽  
Shear Failure ◽  
Short Columns ◽  
Eccentric Compression ◽  
Bending Failure ◽  
Overall Bending ◽  
Compressive Tests

By means of axial compressive and eccentric compressive tests of four Four-tube Concrete-filled Steel Tubular Laced Columns, to research the mechanical properties and failure modes of this structural without yield point. Research shows that, the failure modes of this model, as well as axial compressive short columns, have the same trend of oblique shear failure, and presenting overall bending failure under eccentric compression. The linear eccentricity takes a biggish influence on mechanical properties of laced columns.

scholarly journals Failure mechanism of hollow tree trunks due to cross-sectional flattening

2017 ◽  
Vol 4 (4) ◽  
pp. 160972 ◽  
Author(s):  
Yan-San Huang ◽  
Fu-Lan Hsu ◽  
Chin-Mei Lee ◽  
Jia-Yang Juang
Keyword(s):  
Urban Areas ◽  
Failure Modes ◽  
Shear Failure ◽  
Maximum Shear Stress ◽  
Mode Iii ◽  
Buckling Mode ◽  
Cross Sectional ◽  
Longitudinal Splitting ◽  
Bending Failure ◽  
Hollow Tree

Failure of hollow trees in urban areas is a worldwide concern, and it can be caused by different mechanisms, i.e. bending stresses or flattening-related failures. Here we derive a new analytical expression for predicting the bending moment for tangential cracking, and compare the breaking moment of various failure modes, including Brazier buckling, tangential cracking, shear failure and conventional bending failure, as a function of t / R ratio, where t and R are the trunk wall thickness and trunk radius, respectively, of a hollow tree. We use Taiwan red cypress as an example and show that its failure modes and the corresponding t / R ratios are: Brazier buckling (Mode I), tangential cracking followed by longitudinal splitting (Mode II) and conventional bending failure (Mode III) for 0 <  t / R  < 0.06, 0.06 <  t / R  < 0.27 and 0.27 <  t / R  < 1, respectively. The exact values of those ratios may vary within and among species, but the variation is much smaller than individual mechanical properties. Also, shear failure, another type of cracking due to maximum shear stress near the neutral axis of the tree trunk, is unlikely to occur since it requires much larger bending moments. Hence, we conclude that tangential cracking due to cross-sectional flattening, followed by longitudinal splitting, is dominant for hollow trunks. Our equations are applicable to analyse straight hollow tree trunks and plant stems, but are not applicable to those with side openings or those with only heart decay. Our findings provide insights for those managing trees in urban situations and those managing for conservation of hollow-dependent fauna in both urban and rural settings.

Non-dimensional pressure–impulse diagrams for blast-loaded reinforced concrete beam columns referred to different failure modes

2018 ◽  
Vol 21 (14) ◽  
pp. 2114-2129 ◽  
Author(s):  
Runqing Yu ◽  
Diandian Zhang ◽  
Li Chen ◽  
Haichun Yan
Keyword(s):  
Reinforced Concrete ◽  
Dynamic Response ◽  
Concrete Beam ◽  
Failure Modes ◽  
Shear Failure ◽  
Reinforced Concrete Beam ◽  
Pressure Impulse ◽  
Beam Columns ◽  
Concrete Beam Columns ◽  
Bending Failure

The pressure–impulse diagram is commonly used to assess the damage level of structural components under explosion. Non-dimensional pressure–impulse diagrams referred to different failure modes was obtained using a new methodology in this article. Nine non-dimensional key parameters were first proposed on basis of the Euler beam theory. Considering the shear failure, an elastic–plastic method to calculate the dynamic response of reinforced concrete beam columns was then proposed for different failure modes. Three failure categories, for example, bending failure, shear failure, and combined shear and bending failure, were considered. The threshold between the three failure modes was determined using non-dimensional pressure–impulse curves. A systematic parametric study was conducted to investigate the effects of different non-dimensional parameters on the dynamic response and the failure modes of reinforced concrete beam column. Parametric study shows that the nine non-dimensional key parameters are sufficient to calculate the dynamic response of reinforced concrete beam columns. Moreover, present study shows that the tangent modulus of direct shear stress–slip relation has a great influence on the failure modes. Beam columns with a smaller tangent modulus are more likely to generate combined shear and bending failure mode.

scholarly journals Study on Flexural Behavior of Cross-Laminated Timber Based on Different Tree Species

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Weidong Lu ◽  
Jiahui Gu ◽  
Bibo Wang
Keyword(s):  
Bearing Capacity ◽  
Failure Modes ◽  
Shear Failure ◽  
Flexural Behavior ◽  
Calculation Formula ◽  
Poplar Wood ◽  
Test Results ◽  
Cross Laminated Timber ◽  
Number Of Layers ◽  
Bending Failure

The flexural behavior of CLT panels was experimentally studied. The effects of number of layers, thickness and wood combination on the failure modes, ultimate bearing capacity, stiffness, and ductility of the specimen were analyzed. The test results showed that the flexural strength of the hybrid CLT specimens was basically unchanged, but the stiffness increased by 8% to 22% compared with the CLT specimens of all poplar wood. Compared with the CLT of the whole Douglas fir, the failure mode of the hybrid specimens changes from brittle shear failure to ductile bending failure. Furthermore, the calculation formula of the bending bearing capacity under various failure modes was proposed. The analytical results agreed well with the test results.

Finite Element Simulation on Three-point Bending of Brazed Aluminum Honeycomb Panel

2010 ◽  
Vol 168-170 ◽  
pp. 1046-1050 ◽  
Author(s):  
Ming Jun Peng ◽  
Yong Sun ◽  
Ji Yao ◽  
Yong Hua Duan ◽  
Sai Bei Wang
Keyword(s):  
Failure Modes ◽  
Shear Failure ◽  
Failure Load ◽  
Honeycomb Core ◽  
Three Point Bending ◽  
Aluminum Honeycomb ◽  
Longitudinal Bending ◽  
Panel Thickness ◽  
Bending Failure ◽  
Honeycomb Panel

The mechanics behaviors on three-point bending of brazed aluminum honeycomb panel by FEM are investigated in this paper. The results show that honeycomb panel have three typical failure modes under bending load：failure of honeycomb core collapse, the whole panel bending failure and face sheet shear failure. Honeycomb lateral bending failure load is greater than the longitudinal bending failure load. When the ratio of honeycomb core thickness and panel thickness is between 10% to 15%, the strongest cellular panel bending occurs.

scholarly journals A Cost-Effective Method for Rapid Manufacturing a Precision Mold With Microstructures Using Hybrid Manufacturing Technologies

2021 ◽  
Author(s):  
Chil-Chyuan Kuo ◽  
Bo-Han Lin ◽  
Zheng-Ting Luo
Keyword(s):  
Injection Molding ◽  
Dimensional Accuracy ◽  
Cost Effective ◽  
Numerical Control ◽  
Rapid Manufacturing ◽  
Injection Mold ◽  
Molded Part ◽  
Cost Effective Method ◽  
Length Width ◽  
Manufacturing Technologies

Abstract Injection molding is a cost-effective to manufacture molded products by injection molding machine. A precision part with microstructures can be fabricated effectively through a precision mold. In this study, a cost-effective method for rapid manufacturing a precision component and a precision injection mold with microstructures by integrating additive manufacturing, rapid tooling, and computer numerical control milling. It was found that of the dimensional accuracy of a precision component in the length, width, and height can be controlled at approximately 30 µm. Injection molding was performed using an injection mold with microstructures with a microstructure of 950 µm and the dimensional accuracy of a molded part in the length, width, and microstructure can be controlled at approximately 60 µm, 50 µm, and 10 µm, respectively. The remarkable findings of this study can be used for the fabrication of molds or dies efficiently and economically for trial production in the mold industry since the quality of the precision component and the precision mold can meet the standards of the general industry.

CAD Of Anticorrosive Protection Of Steel Structures

2019 ◽  
pp. 18-23
Keyword(s):  
Protective Coating ◽  
Computer Aided Design ◽  
Steel Structures ◽  
Cost Effective ◽  
Operating Conditions ◽  
Computational Tool ◽  
Protection Method ◽  
Cost Effective Method ◽  
The Cost ◽  
Aided Design

The choice of cost-effective method of anticorrosive protection of steel structures is an urgent and time consuming task, considering the significant number of protection ways, differing from each other in the complex of technological, physical, chemical and economic characteristics. To reduce the complexity of solving this problem, the author proposes a computational tool that can be considered as a subsystem of computer-aided design and used at the stage of variant and detailed design of steel structures. As a criterion of the effectiveness of the anti-corrosion protection method, the cost of the protective coating during the service life is accepted. The analysis of existing methods of steel protection against corrosion is performed, the possibility of their use for the protection of the most common steel structures is established, as well as the estimated period of effective operation of the coating. The developed computational tool makes it possible to choose the best method of protection of steel structures against corrosion, taking into account the operating conditions of the protected structure and the possibility of using a protective coating.

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