Deflectometric analysis of high volume injection molds for production of occupational eye wear

Speck, Alexis; Zelzer, Benedikt; Speich, Marco; Börret, Rainer; Langenbucher, Achim; Eppig, Timo

doi:10.1016/j.zemedi.2013.08.003

Cited by 2 publications

(1 citation statement)

References 18 publications

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“…In previous publications we proposed a prototype of a deflectometric inspection of mold surfaces [7,8]. The deflectometric method allows extraction of height data and detection of defects on the mold surfaces.…”

Section: Introductionmentioning

confidence: 99%

Quality control of injection molded eyewear by non-contact deflectometry

Speck

Zelzer

Langenbucher

et al. 2014

J. Eur. Opt. Soc.-Rapid Publ.

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Occupational eye wear such as safety spectacles are manufactured by injection molding techniques. Testing of the assembled safety spectacle lenses in transmission is state of the art, but there is a lack of surface measurement systems for occupational safety lenses. The purpose of this work was to validate a deflectometric setup for topography measurement, detection of defects and visualization of the polishing quality, e.g. casting indentations or impressions, for the production process of safety spectacles. The setup is based on a customized stereo phase measuring deflectometer (PMD), equipped with 3 cameras with f'1,2 = 16 mm and f'3 = 8.5 mm and a specified measurement uncertainty of ± 3 µm. Sixteen plastic lenses and 8 corresponding injection molds from 4 parallel cavities were used for validation of the deflectometer. For comparison an interferometric method and a reference standard (< λ/10 super polished) was used. The accuracy and bias with a spherical safety spectacle sample was below 1 µm, according to DIN ISO 5725-2.2002-12. The repeatability was 2.1 µm and 35.7 µm for a blind radius fit. In conclusion, the PMD technique is an appropriate tool for characterizing occupational safety spectacle and injections mold surfaces. With the presented setup we were able to quantify the surface quality. This can be useful and may optimize the quality of the end product, in addition to standardized measuring systems in transmission.

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Section: Introductionmentioning

confidence: 99%

Quality control of injection molded eyewear by non-contact deflectometry

Speck

Zelzer

Langenbucher

et al. 2014

J. Eur. Opt. Soc.-Rapid Publ.

View full text Add to dashboard Cite

show abstract

Study of Injection Molding Process to Improve Geometrical Quality of Thick-Walled Polycarbonate Optical Lenses by Reducing Sink Marks

Vanek,

Ovsik,

Stanek

et al. 2024

Polymers

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This study investigates the challenges and potential of conventional injection molding for producing thick-walled optical components. The research primarily focuses on optimizing process parameters and mold design to enhance product quality. The methods include software simulations and experimental validation using polycarbonate test samples (optical lenses). Significant parameters such as melt temperature, mold temperature, injection pressure, and packing pressure were varied to assess their impact on geometric accuracy and visual properties. The results show that lower melt temperatures and higher mold temperatures significantly reduce the occurrence of dimensional defects. Additionally, the design of the gate system was found to be crucial in minimizing defects and ensuring uniform material flow. Effective packing pressure was essential in reducing volumetric shrinkage and sink marks. Furthermore, we monitored the deviation between the predicted and actual defects relative to the thickness of the sample wall. After optimization, the occurrence of obvious defects was eliminated across all sample thicknesses (lenses), and the impact of the critical defect, the sink mark on the planar side of the lens, was minimized. These findings demonstrate the substantial potential of conventional injection molding to produce high-quality thick-walled parts when these parameters are precisely controlled. This study provides valuable insights for the efficient design and manufacturing of optical components, addressing the growing demand for high-performance thick-walled plastic products.

show abstract

Deflectometric analysis of high volume injection molds for production of occupational eye wear

Cited by 2 publications

References 18 publications

Quality control of injection molded eyewear by non-contact deflectometry

Quality control of injection molded eyewear by non-contact deflectometry

Study of Injection Molding Process to Improve Geometrical Quality of Thick-Walled Polycarbonate Optical Lenses by Reducing Sink Marks

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