Investigating the technological limits of micro-injection molding in replicating high aspect ratio micro-structured surfaces

Lucchetta, Giovanni; Sorgato, Marco; Carmignato, Simone; Savio, Enrico

doi:10.1016/j.cirp.2014.03.049

Cited by 83 publications

(71 citation statements)

References 11 publications

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“…One of the main challenges associated with micro-molding resides in difficulties of controlling structures or mechanical properties of the parts [2][3]. MIM parts often exhibit a "skin-core" structure which is similar to that of conventional injection molding parts, expect that the oriented layer represents a large fraction [4].…”

Section: Introductionmentioning

confidence: 99%

Effect of mold temperature on the structures and mechanical properties of micro-injection molded polypropylene

et al. 2015

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Section: Introductionmentioning

confidence: 99%

Effect of mold temperature on the structures and mechanical properties of micro-injection molded polypropylene

et al. 2015

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“…lenses, sensors) and industrial products. Due to their high flowability, low density, high transparency and low birefringence, these materials are designed to use in micro injection moulding [16]. Its properties are provided in Table 2.…”

Section: Test Materialsmentioning

confidence: 99%

“…They speculate that, air evacuation could lead to a decrease of the surface temperature in micro features as a result of removing warm air from the cavity. Hence, with the increase of the surface-to-volume ratio in micro cavities, air evacuation could have a detrimental effect on the melt fill, especially for polymers that have a high temperature dependence of viscosity [16].…”

Section: Introductionmentioning

confidence: 99%

Investigation of the influence of vacuum venting on mould surface temperature in micro injection moulding

Sorgato

Babenko

Lucchetta

et al. 2016

Int J Adv Manuf Technol

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The application of vacuum venting for the removal of air from mould cavity has been introduced in injection moulding with the intent to enhance micro/nano features replication and definition. The technique is adopted to remove air pockets trapped in the micro-features, which are out of reach for conventional venting technologies and can create considerable resistance to the melt filling flow. Nonetheless, several studies have revealed a negative effect on replication that could possibly arise from the application of vacuum venting. Although the incomplete filling of micro-scale features has often been attributed to poor venting, the limited research examining the application of vacuum venting has produced mixed results. In this work, the effect of air evacuation was experimentally investigated, monitoring mould and polymer temperature evolution during the micro injection moulding process by means of a high speed infrared camera and a sapphire window, which forms part of the mould wall. The results show that air evacuation removes a mould surface heating effect caused by rapid compression of the air ahead of the flow front and subsequent conduction of that heat into the mould surface. Hence, with the increase of the surface-to-volume ratio in micro-cavities, air evacuation has a detrimental effect on the cavity filling with polymers that are sensitive to changes of the mould temperature.

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“…This is reflected by an increasing interest of industries in micro-molding processes. In order to fabricate a micro-structured tool (mold insert), the miniaturization of chemical and mechanical devices for micro-electromechanical systems (MEMS) has received a great deal of attention [4][5][6]. The appearance of the LIGA-like technology led to a new challenge in the thermoplastic molding of micro-structures, i.e., replication of high aspect ratios (A.R.).…”

Section: Introductionmentioning

confidence: 99%

Study On The External Gas-Assisted Mold Temperature Control For Thin Wall Injection Molding

Do¹

2017

IJERA

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Dynamic mold surface temperature control (DMTC) has many advantages in micro-injection molding as well as thin-wall molding product. In this paper, DMTC will be applied for the thin-wall molding part with the observation of the weldline appearance and the weldline strength. The heating step of DMTC will be achieved by the hot air flow directly to the weldline area. The results show that the heating rate could be reached to 4.5C/s, which could raising the mold surface from 30C to over 120C within 15 s. The melt filling was operated with high temperature at the weldline area; therefore, the weldline appearance was eliminated. In addition, the weldline strength was also improved. The results show that the thinner part had the higher strength of the weldline.

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Investigating the technological limits of micro-injection molding in replicating high aspect ratio micro-structured surfaces

Cited by 83 publications

References 11 publications

Effect of mold temperature on the structures and mechanical properties of micro-injection molded polypropylene

Effect of mold temperature on the structures and mechanical properties of micro-injection molded polypropylene

Investigation of the influence of vacuum venting on mould surface temperature in micro injection moulding

Study On The External Gas-Assisted Mold Temperature Control For Thin Wall Injection Molding

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