Polymer Flow Influenced by Mold Cavity Surface Roughness

Staněk, Michal; Maňas, David; Ovsík, Martin; Řezníček, Martin; Senkerik, Vojtech; Janostik, Vaclav

doi:10.21062/ujep/291.2019/a/1213-2489/mt/19/2/327

Cited by 5 publications

(4 citation statements)

References 5 publications

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“…These results were confirmed by multiple other tested materials, as can be seen in previously published studies [29][30][31][32]. The measurements indicate that rougher surfaces left after electrical discharge machining (Ra 4.4), milling (Ra 1.6) and grinding (Ra 0.8) consist of irregular structures, which are not fully filled by the hot melt during injection moulding.…”

Section: Flow Lengthsupporting

confidence: 86%

The influence of tool’s surface topography on mechanical properties of injection moulded product

Ovsík

Staněk

Dockal

et al. 2022

Surf. Topogr.: Metrol. Prop.

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This publication deals with influence of tool topography (injection mould) on properties of a product. Surface of the mould was machined by various finishing technologies (milling, grinding, polishing and electrical discharge machining) which resulted in varying surface quality of the tool. The tested topography had an effect on the flow length of polymer and topographical and mechanical properties of the specimen. Examined properties (surface topography and mechanical properties) were measured in several places along the length of the product (starting at the gate and finishing at the end of the specimen). The results show that increase of the tool’s surface roughness leads to longer flow length. These findings disprove the necessity for polishing of each and every shaping part of the mould when manufacturing non-visual products. Thus, from economical and manufacturing perspective the milled or grinded tool surfaces are sufficient. Furthermore, replication of the tool’s topography is non-homogenous, which results in varying mechanical properties throughout the product. The discrepancy in mechanical properties along the length of the product is caused by differing cooling speeds in the mould. In practice, guided cooling can be used to achieve varying mechanical properties in desired places of the injected article. For example, highly stressed parts can be manufactured with the goal of having improved mechanical properties in specific places of the product. Future application of these findings poses a significant benefit for industrial practice, as it could lower the manufacturing cost of the injection mould in order of tens of percent.

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Section: Flow Lengthsupporting

confidence: 86%

The influence of tool’s surface topography on mechanical properties of injection moulded product

Ovsík

Staněk

Dockal

et al. 2022

Surf. Topogr.: Metrol. Prop.

Self Cite

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show abstract

“…However, only a handful of these publications were concerned with the effect of the surface quality, its replication ability and the applied processing parameters on the final product. Furthermore, no complex study analysing the influence of surface quality on the flow length of a polymer or the effect of flow length on the mechanical properties has yet been completed [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

“…There are comparative costs also with different manufacturing processes. As can be seen, machining costs steeply escalate with decreasing surface roughness values [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

The Influence of Surface Quality on Flow Length and Micro-Mechanical Properties of Polycarbonate

et al. 2021

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This study describes the influence of polymer flow length on mechanical properties of tested polymer, specifically polycarbonate. The flow length was examined in a spiral shaped mould. The mould cavity’s surface was machined by several methods, which led to differing roughness of the surface. The cavity was finished by milling, grinding and polishing. In order to thoroughly understand the influence of the mould surface quality on the flow length, varying processing parameters, specifically the pressure, were used. The polymer part was divided into several segments, in which the micro-mechanical properties, such as hardness and indentation modulus were measured. The results of this study provide interesting data concerning the flow length, which was up to 3% longer for rougher surfaces, but shorter in cavities with polished surface. These results are in disagreement with the commonly practiced theory, which states that better surface quality leads to greater flow length. Furthermore, evaluation of the micro-mechanical properties measured along the flow path demonstrated significant variance in researched properties, which increased by 35% (indentation hardness) and 86% by indentation modulus) in latter segments of the spiral in comparison with the gate.

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“…The heat transfer coefficient (HTC) increased with the increasing of cavity surface roughness, which helped the polymer flow [ 26 ]. However, some other researchers believed that the cavity surface roughness hindered the polymer flow [ 27 ] or had no effects on the polymer [ 28 ] flow in the cavity. The reason for the contradiction was mainly due to the difference in cavity size, in particular, the thickness of the cavity.…”

Section: Introductionmentioning

confidence: 99%

Effects of Cavity Thickness and Mold Surface Roughness on the Polymer Flow during Micro Injection Molding

Liu

et al. 2023

Polymers

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In micro injection molding, the cavity thickness and surface roughness are the main effects factors of polymer flow in the die designing and affect the quality of molded products significantly. In this study, the effects of cavity thickness and roughness of cavity surface were investigated mainly on polymer flow during molding and on the roughness of molded products. The parts were molded in the cavities with the thickness from 0.05 mm to 0.25 mm and surface roughness from Ra = 46.55 nm to Ra = 462.57 nm, respectively. The filling integrities and roughness replication ratio of molded parts were used to evaluate the statements of polymer flow and microstructure replication during micro injection molding, respectively. The results showed that the filling integrity changing trends in the thinner cavities were obviously different or even opposite to those in the thicker cavities with the changing of cavity surface roughness instead of single trend in the conventional studies. For each cavity surface roughness, the filling integrity showed an upward trend with the increasing cavity thickness. In different cavity thickness, the maximum gap of filling integrity was 23.76 mm, reaching 544.94% from 0.05 mm to 0.25 mm. Additionally, the surface roughness ratio was slightly smaller than one before, reaching the polymer surface roughness limit around Ra = 71.27 nm, which was decided by the nature of the polymer itself. This study proposed the references for the design and fabrication of mold cavities and parts, and saved time and cost in the actual product manufacturing.

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Polymer Flow Influenced by Mold Cavity Surface Roughness

Cited by 5 publications

References 5 publications

The influence of tool’s surface topography on mechanical properties of injection moulded product

The influence of tool’s surface topography on mechanical properties of injection moulded product

The Influence of Surface Quality on Flow Length and Micro-Mechanical Properties of Polycarbonate

Effects of Cavity Thickness and Mold Surface Roughness on the Polymer Flow during Micro Injection Molding

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