scholarly journals Surface strengthening of injection molded parts by applying a thermal insulation film

RSC Advances ◽  
2017 ◽  
Vol 7 (23) ◽  
pp. 14302-14308 ◽  
Author(s):  
Hwa Jin Oh ◽  
Young Seok Song
Keyword(s):  
Residual Stress ◽  
Thermal Insulation ◽  
Compressive Residual Stress ◽  
Surface Strengthening ◽  
Molded Parts ◽  
Injection Molded

The main objective of this study is to strengthen the surface of injection molded parts by building up the compressive residual stress at the surface of the product.

Residual Stress and Warpage Models for Complex Injection Molded Parts

2002 ◽  
Vol 17 (3) ◽  
pp. 271-278 ◽  
Author(s):  
W.-B. Young ◽  
J. Wang
Keyword(s):  
Residual Stress ◽  
Molded Parts ◽  
Injection Molded

Numerical simulation and experimental validation of residual stress induced constrained shrinkage of injection molded parts

Polimery ◽  
2008 ◽  
Vol 53 (04) ◽  
pp. 304-310 ◽  
Author(s):  
TAHER AZDAST ◽  
AMIR HOSSEIN BEHRAVESH ◽  
KIUMARS MAZAHERI ◽  
MOHAMMAD MEHDI DARVISHI
Keyword(s):  
Numerical Simulation ◽  
Residual Stress ◽  
Experimental Validation ◽  
Molded Parts ◽  
Injection Molded

Residual Stress in a Quenched Gear Shaft Treated by Water Cavitation Peening

2005 ◽  
Vol 490-491 ◽  
pp. 364-369 ◽  
Author(s):  
H. Tsuda ◽  
Dong Ying Ju ◽  
T. Uchiyama ◽  
Y. Sunayama ◽  
R. Oba
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Compressive Residual Stress ◽  
Diffraction Method ◽  
Tooth Surface ◽  
Material Surface ◽  
Process Conditions ◽  
Strengthening Effect ◽  
Surface Strength ◽  
Surface Strengthening

Water cavitation technique can be applied to modify the surface strength of materials as an attractive new peening route. By inducing cavitation of ultrahigh speed water due to water-jet, the numerous impacts induced by the cavitation bubbles impact can produce compressive residual stress on material surface in the similar way as that by shot peening. In the present paper, an automobile part of steel gear shaft with complex shape is processed by water peening process. Compressive residual stress induced by water peening was measured to investigate the surface strengthening effect as a quantitative factor. The residual stresses on the tooth surface of the gear are measured by X-ray diffraction method. The effect of process conditions such as water outlet pressure, standoff distance of the nozzle, and peening time are discussed. To investigate the effect of heat treatment, carburizing-quenching is implemented to the gear shaft. By comparing the residual stresses of the tooth before and after water peening, the effectiveness of water peening process on surface strengthening is verified for a quenched gear shaft.

scholarly journals Fatigue Limit of Custom 465 with Surface Strengthening Treatment

Materials ◽  
2020 ◽  
Vol 13 (1) ◽  
pp. 238 ◽  
Author(s):  
Gang An ◽  
Ren-jing Liu ◽  
Guang-qiang Yin
Keyword(s):  
Residual Stress ◽  
Fatigue Crack ◽  
Fatigue Limit ◽  
Shot Peening ◽  
Compressive Residual Stress ◽  
Subsurface Layer ◽  
Micro Hardness ◽  
Surface Residual Stress ◽  
Surface Strengthening ◽  
The Relationship

In order to study the effect of nitriding or shot peening on the surface modification and fatigue properties of martensitic stainless-steel Custom 465, the residual stress and micro-hardness of the strengthened layer are determined by X-ray and micro-hardness tester, respectively. The up-and-down method is used to measure the rotational bending fatigue strength at 1 × 107 cycles, and the fatigue fracture characteristic is observed by scanning electron microscopy. The relationship between surface residual stress and internal fatigue limit of surface strengthening treatment is discussed. Results show that nitriding or shot peening surface strengthening layer forms a certain depth of compressive residual stress, where in the surface compressive residual stress of the nitrided specimens is greater than the shot peened specimens. The micro-hardness of the nitrided or shot peened surface strengthening layer is significantly improved, where in the surface micro-hardness of nitriding specimens are higher than shot peening specimens. The nitriding or shot peening surface strengthening can significantly improve the fatigue limit of Custom 465, wherein the fatigue limits of nitrided and shot peened surface strengthened specimens are 50.09% and 50.66% higher than that of the un-surface strengthened specimens, respectively. That is, the effect of the two strengthening methods on fatigue limit is not very different. The fracture characteristics show that the fatigue crack of the un-surface strengthened specimens originates from the surface, while the fatigue crack of surface strengthened specimens originates from the subsurface layer under the strengthened layer. The relationship between the internal fatigue limit and the surface residual stress of the surface strengthened specimen can be used as a method for predicting the fatigue limit of the surface strengthened specimens.

scholarly journals Study about the technique of determining residual stress of loading measuring method

2021 ◽  
Vol 13 (5) ◽  
pp. 168781402110169
Author(s):  
Liu Hong ◽  
Jiang Zheqi ◽  
Pan Danqi
Keyword(s):  
Residual Stress ◽  
Nondestructive Test ◽  
Measuring Method ◽  
Test Method ◽  
Hole Drilling ◽  
Hole Drilling Method ◽  
Molded Part ◽  
Molded Parts ◽  
Injection Molded ◽  
A New Technique

Nondestructive test method for residual stress in a structural member is always an important research subject, as a new technique for measuring residual stress loading measuring method needs to consummate for the convenience of engineering. The paper proves that nondestructive test loading measuring method is effective and accurate when compared with the result from hole-drilling method. Taking the measurement of residual stress of injection-molded part in automotive lamp as example, the residual stresses in the surface of injection-molded parts of automotive lamp measured by the two methods are very close based on the two measuring results. It shows that loading measuring method, a new method is used to measure the residual stress, has enough accuracy and credibility when it is used to measure the residual stress of complicated injection-molded part. It provides a basis for popularization and application of loading measuring method in engineering. The paper discusses the basic principles of loading measuring method and detailed procedure of the measurement of residual stress by loading measuring method; it gives out some advices to reduce the test errors.

Effect of gate size on the melt filling behavior and residual stress of injection molded parts

2014 ◽  
Vol 53 ◽  
pp. 366-372 ◽  
Author(s):  
Pengcheng Xie ◽  
Fengxia Guo ◽  
Zhiwei Jiao ◽  
Yumei Ding ◽  
Weimin Yang
Keyword(s):  
Residual Stress ◽  
Molded Parts ◽  
Injection Molded ◽  
Gate Size

Effects of Process Conditions on Shrinkage and Warpage: Experiments and Simulations

2000 ◽  
Author(s):  
James T. Wang ◽  
C. K. Yoon
Keyword(s):  
Residual Stress ◽  
Mold Wall ◽  
Polymer Melt ◽  
Process Conditions ◽  
Cooling Channels ◽  
Part Quality ◽  
Molded Part ◽  
Packing Pressure ◽  
Molded Parts ◽  
Injection Molded

Abstract In the injection mold process, a pressure gradient exists from the polymer entrance to the last-fill location. At different planar locations of a part, when the polymer melt cools down to the transition temperature and freezes (changes from liquid to solid) at different pressures, shrinkage at the various locations will be different. If cooling channels are not arranged properly, the mold wall temperatures on the cavity and core sides can be different. This unbalanced cooling can also cause the melt at the upper and lower halves of the cavity to shrink differently, because they freeze at different times and different pressures. These two types of non-uniform shrinkage will cause parts to warp. Reducing shrinkage and warpage is one of the top priorities for improving the quality of injection molded parts. In addition to part design and material properties, process conditions are the most important determinants of part quality. In this paper, the relationship between process conditions and in-cavity residual stress will be studied. In-cavity residual stress is the driving force that causes parts to deform after they are taken out of the mold. The effects of process conditions on injection-molded part quality (in terms of shrinkage and warpage) will be discussed. Different packing pressure levels, together with unbalanced cooling from mold wall temperatures, will be examined. Deformation of injection molded parts will be measured. Comparisons between experimental and numerical simulation results will be reported.

Comparative Analysis of Different Methods in Residual Stress Measurement for Polymeric Parts

2013 ◽  
Vol 837 ◽  
pp. 175-178
Author(s):  
Alexandra Raicu
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Polymeric Materials ◽  
Injection Molding Process ◽  
Uniform Temperature ◽  
Molding Process ◽  
Molded Parts ◽  
Injection Molded ◽  
Technological Constraints

This paper presents the measurements of the residual stresses for polymeric parts using different methods. The residual stresses are usually introduced during manufacturing and are caused by processes such as molding. In order to optimize injection molding process with polymeric material, it is important to predict the internal stress development during molding. The residual stresses are caused mainly by non-uniform temperature profile in the cavity during filling, packing and cooling stages. This research offers information and a methodology which may be applied in practical conditions for a large number of parts manufactured from the different polymeric materials and for several technological constraints. The author confirmed that all this methods which measure the residual stresses can be applied to injection molded parts.

Monitoring of mechanical properties of prestressed glass fiber epoxy composites over 12 months after fabrication

2021 ◽  
pp. 002199832110047
Author(s):  
Mahmoud Mohamed ◽  
Siddhartha Brahma ◽  
Haibin Ning ◽  
Selvum Pillay
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Flexural Strength ◽  
Compressive Residual Stress ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Epoxy Composites ◽  
Flexural Properties ◽  
Initial Increase ◽  
Fiber Volume

Fiber prestressing during matrix curing can significantly improve the mechanical properties of fiber-reinforced polymer composites. One primary reason behind this improvement is the generated compressive residual stress within the cured matrix, which impedes cracks initiation and propagation. However, the prestressing force might diminish progressively with time due to the creep of the compressed matrix and the relaxation of the tensioned fiber. As a result, the initial compressive residual stress and the acquired improvement in mechanical properties are prone to decline over time. Therefore, it is necessary to evaluate the mechanical properties of the prestressed composites as time proceeds. This study monitors the change in the tensile and flexural properties of unidirectional prestressed glass fiber reinforced epoxy composites over a period of 12 months after manufacturing. The composites were prepared using three different fiber volume fractions 25%, 30%, and 40%. The results of mechanical testing showed that the prestressed composites acquired an initial increase up to 29% in the tensile properties and up to 32% in the flexural properties compared to the non-prestressed counterparts. Throughout the 12 months of study, the initial increase in both tensile and flexural strength showed a progressive reduction. The loss ratio of the initial increase was observed to be inversely proportional to the fiber volume fraction. For the prestressed composites fabricated with 25%, 30%, and 40% fiber volume fraction, the initial increase in tensile and flexural strength dropped by 29%, 25%, and 17%, respectively and by 34%, 26%, and 21%, respectively at the end of the study. Approximately 50% of the total loss took place over the first month after the manufacture, while after the sixth month, the reduction in mechanical properties became insignificant. Tensile modulus started to show a very slight reduction after the fourth/sixth month, while the flexural modulus reduction was observed from the beginning. Although the prestressed composites displayed time-dependent losses, their long-term mechanical properties still outperformed the non-prestressed counterparts.

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