Injection molding of products with functional surfaces by micro-structured, PVD coated injection molds

Bobzin, Kirsten; Bagcivan, Nazlim; Gillner, Arnold; Hartmann, Claudia; Holtkamp, Jens; Michaeli, Walter; Klaiber, Fritz; Schöngart, Maximilian; Theiß, Sebastian

doi:10.1007/s11740-011-0319-9

Cited by 18 publications

(13 citation statements)

References 16 publications

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“…In other cases, however, there may be a number of options available. For the injection moulding inlay, one can use the native surface or apply a surface coating . Together, these choices define the surface energy at the polymer/inlay interface.…”

Section: Resultsmentioning

confidence: 99%

Strategies for High Quality Injection Moulding of Polymer Nanopillars

Pedersen

Stormonth-Darling

et al. 2014

Macro Materials & Eng

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Injection moulding is a proven technology for high-throughput production of nanostructures, but high quality replication of pillar-type structures is a considerable challenge, due to the complexities of cavity filling at the timescales involved. We have developed a platform to systematically study the effects of nanostructures with aspect ratios up to 1.2:1 on the quality of moulding, and also considered options for polymer and tooling material. A master template containing nanostructures with a continuous variation in height is produced by a novel fabrication approach using a plasma polymerized hexane layer, deposited with a gradient in thickness, as a sacrificial etch mask. Injection moulding results show that process parameters (tooling temperature and cooling time), material (polystyrene and polycarbonate) as well as a tool surface coating can control the stretching of nanopillar replica dimensions, allowing a variety of final pattern heights using a single master.-2 -

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Section: Resultsmentioning

confidence: 99%

Strategies for High Quality Injection Moulding of Polymer Nanopillars

Pedersen

Stormonth-Darling

et al. 2014

Macro Materials & Eng

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“…Since the formation of a viscous or solidified layer hinders replication, it is widely recognized that replication is improved by raising melt injection temperature or cavity (insert) surface temperature . Raising these temperatures while keeping other parameters fixed will, however, reduce filling pressure.…”

Section: Replication Of Micro‐features In Injection Moldingmentioning

confidence: 99%

Replication of surface micro‐features using variothermal injection molding: Application to micro‐fluidics

Pittman¹,

Wlodarski²

2017

Polymer Engineering & Sci

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We study injection molding of mesoscale items with µm‐scale surface features, namely micro‐fluidic channels, relating replication quality to process conditions. Using variothermal molding, the variables are the pre‐heat temperature of the cavity insert surface before melt injection and the mold cooling start time. Surface temperatures and in‐cavity melt pressures are continuously measured. Rounded upper corners of the micro‐channels are used as an index of replication quality. For polymethylmethacrylate the thickness of a layer with solid‐like properties (below 124°C) is calculated and used with pressures to interpret results. It is shown how improved replication correlates with low layer thickness at the end of the compression phase when pressures are at a maximum, and the necessity of properly timed cooling to lock in replication before melt pressures fall. Results show how the inter‐relationship of layer thickness and melt pressure is controlled by pre‐heat temperature and cooling switch‐on time. Delayed cooling can result in poorer replication, due to a retraction effect of the plastic. Too early cooling also reduces replication of parallel‐to‐flow features downstream of transverse features, and of the replication of transverse features on their downstream side. Good replication of 100 and 70 µm channels requires lower pre‐heat than 400 µm ones. POLYM. ENG. SCI., 58:1726–1738, 2018. © 2017 Society of Plastics Engineers

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“…In recent years it was shown that this technology offers a wide range of possibilities to produce ternary metastable material compounds [5]. Some of these coating systems were tested in components of injection moulding machines [1,5,6]. It was shown that the number of defects in the moulded parts and the adhesion of plastics melt can be reduced by using coatings like TiN, TiAlN, TiAlON, CrN, CrAlN and CrAlON [7].…”

Section: Coating Of the Mould Insertsmentioning

confidence: 99%

“…Integrating additional functional surfaces such as the application of micro structures, the existing functions can be made more efficient or even new functions can be realised. For a successful one-step production of micro-structured surfaces, an integrated approach to the entire process chain is required, since mould, material and replication process have all strong inter-dependencies [1]. Laser ablation is a well suited and promising technique for the creation of micro structured moulds since it is a tool-free process with a large degree of freedom in geometry and structure size.…”

Section: Introductionmentioning

confidence: 99%

Injection moulding of optical functional micro structures using laser structured, PVD-coated mould inserts

Hopmann

Weber

Schöngart

et al. 2015

AIP Conference Proceedings

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Abstract. Micro structured optical plastics components are intensively used i. e. in consumer electronics, for optical sensors in metrology, innovative LED-lighting or laser technology. Injection moulding has proven to be successful for the large-scale production of those parts. However, the production of those parts still causes difficulties due to challenges in the moulding and demoulding of plastics parts created with laser structured mould inserts. A complete moulding of the structures often leads to increased demoulding forces, which then cause a breaking of the structures and a clogging of the mould. An innovative approach is to combine PVD-coated (physical vapour deposition), laser structured inserts and a variothermal moulding process to create functional mic8iüro structures in a one-step process. Therefore, a PVD-coating is applied after the laser structuring process in order to improve the wear resistance and the anti-adhesive properties against the plastics melt.In a series of moulding trials with polycarbonate (PC) and polymethylmethacrylate (PMMA) using different coated moulds, the mould temperature during injection was varied in the range of the glass transition and the melt temperature of the polymers. Subsequently, the surface topography of the moulded parts is evaluated by digital 3D laser-scanning microscopy. The influence of the moulding parameters and the coating of the mould insert on the moulding accuracy and the demoulding behaviour are being analysed. It is shown that micro structures created by ultra-short pulse laser ablation can be successfully replicated in a variothermal moulding process. Due to the mould coating, significant improvements could be achieved in producing micro structured optical plastics components.

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Injection molding of products with functional surfaces by micro-structured, PVD coated injection molds

Cited by 18 publications

References 16 publications

Strategies for High Quality Injection Moulding of Polymer Nanopillars

Strategies for High Quality Injection Moulding of Polymer Nanopillars

Replication of surface micro‐features using variothermal injection molding: Application to micro‐fluidics

Injection moulding of optical functional micro structures using laser structured, PVD-coated mould inserts

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