A closed-loop intelligent adjustment of process parameters in precise and micro hot-embossing using an in-process optic detection

2021 ◽  
Author(s):  
Kuo Lu ◽  
Jin Xie ◽  
Risen Wang ◽  
Lei Li ◽  
Wenzhe Li ◽  
...  
Keyword(s):  
Process Parameters ◽  
Closed Loop ◽  
Hot Embossing

scholarly journals Measurement and Process Control in Precision Hot Embossing

2013 ◽  
Author(s):  
Maia R. Bageant ◽  
David E. Hardt
Keyword(s):  
Process Control ◽  
Material Properties ◽  
Disturbance Rejection ◽  
Closed Loop ◽  
Hot Embossing ◽  
Commercial Production ◽  
Bulk Deformation ◽  
Functional Tests ◽  
Medical Field ◽  
High Degree

Microfluidic technologies hold a great deal of promise in advancing the medical field, but transitioning them from research to commercial production has proven problematic. We propose precision hot embossing as a process to produce high volumes of devices with low capital cost and a high degree of flexibility. Hot embossing has not been widely applied to precision forming of hard polymers at viable production rates. To this end we have developed experimental equipment capable of maintaining the necessary precision in forming parameters while minimizing cycle time. In addition, since equipment precision alone does not guarantee consistent product quality, our work also focuses on real-time sensing and diagnosis of the process. This paper covers both the basic details for a novel embossing machine, and the utilization of the force and displacement data acquired during the embossing cycle to diagnose the state of the material and process. The precision necessary in both the forming machine and the instrumentation will be covered in detail. It will be shown that variation in the material properties (e.g. thickness, glass transition temperature) as well as the degree of bulk deformation of the substrate can be detected from these measurements. If these data are correlated with subsequent downstream functional tests, a total measure of quality may be determined and used to apply closed-loop cycle-to-cycle control to the entire process. By incorporating automation and specialized precision equipment into a tabletop “microfactory” setting, we aim to demonstrate a high degree of process control and disturbance rejection for the process of hot embossing as applied at the micron scale.

Parametric Study of Hot Embossing on Micro-Holes

2009 ◽  
Vol 74 ◽  
pp. 251-254
Author(s):  
Cheng Hsien Wu ◽  
Chen Hao Hung ◽  
Ya Zhen Hu
Keyword(s):  
Process Parameters ◽  
Parametric Study ◽  
Hot Embossing ◽  
Micro Holes ◽  
Very High

This report describes the application of hot embossing to produce parts with microstructure. An embossing machine, designed for microfabrication, was used to emboss PMMA and PC substrates. An insert with micro-holes of various diameters was applied in the hot embossing experiments. Effects of process parameters, such as embossing temperature, embossing force, embossing period and demolding temperature, on replicated heights were studied. Results show that replicated heights on smaller holes are smaller. Embossing temperature is the most important factor. Demolding temperature hardly affects the replication ability. Replicated heights increase with embossing period. The height can reach a very high value with a large enough embossing period.

Computational Modeling of Polymer Flow in Microcavities Through a Microscreen

2010 ◽  
Author(s):  
Jie Chen ◽  
Ranga Pitchumani
Keyword(s):  
Injection Molding ◽  
Computational Modeling ◽  
Computational Model ◽  
Process Parameters ◽  
Polymer Melts ◽  
Hot Embossing ◽  
Temperature Dependent ◽  
Polymer Flow ◽  
Feature Geometry ◽  
A New Technique

This paper investigates a new technique for rapid replication of electroforming micromolds with integral microscreens. The process is based on injection molding or hot embossing of plastic replicates with integral metallic screens onto a LIGA-fabricated master microtool, to produce sacrificial electroforming molds in which the metallic screen acts as the conducting base and the plastic features provide insulating sidewalls for electrodeposition of the desired metallic micropart. A computational model is developed for the polymer flow during the fabrication of electroforming micromolds incorporating the temperature dependent, non-Newtonian rheology of the polymer melts. The model is used to analyze the effects of the process parameters and micro-feature geometry on the polymer flow patterns.

Simulation and Experimental Study of the Effects of Process Factors on the Uniformity of the Residual Layer Thickness in Hot Embossing

2013 ◽  
Vol 1 (2) ◽  
Author(s):  
F. Omar ◽  
A. Kolew ◽  
E. B. Brousseau ◽  
H. Hirshy
Keyword(s):  
Standard Deviation ◽  
Layer Thickness ◽  
Process Parameters ◽  
Hot Embossing ◽  
Residual Layer ◽  
Holding Time ◽  
Influential Factor ◽  
Molding Temperature ◽  
Process Factors ◽  
Thickness Measurements

Hot embossing replica are characterized by the quality of the molded structures and the uniformity of the residual layer. In particular, the even distribution of the residual layer thickness (RLT) is an important issue in hot embossing and the related process of thermal nanoimprint lithography, as variations in the RLT may affect the functionality or further processing of replicated parts. In this context, the paper presents an experimental and simulation study on the influence of three process factors, namely the molding temperature, the embossing force, and the holding time, on the residual layer homogeneity achieved when processing 2 mm thick PMMA sheets with hot embossing. The uniformity of the RLT was assessed for different experimental conditions by calculating the standard deviation of thickness measurements at different set locations over the surface of each embossed sample. It was observed that the selected values of the studied parameters have an effect on the resulting RLT of the PMMA replica. In particular, the difference between the largest and lowest RLT standard deviation between samples was 18 μm, which was higher than the accuracy of the instrument used to carry out the thickness measurements. In addition, the comparison between the obtained experimental and simulation results suggests that approximately 12% of the RLT uniformity was affected by the local deflections of the mold. Besides, polymer expansion after release of the embossing load was estimated to contribute to 8% of the RLT nonuniformity. It is essential to understand the effects of the process parameters on the resulting homogeneity of the residual layer in hot embossing. In this research, the best RLT uniformity could be reached by using the highest considered settings for the temperature and holding time and the lowest studied value of embossing force. Finally, the analysis of the obtained results also shows that, across the range of processing values studied, the considered three parameters have a relatively equal influence on the RLT distribution. However, when examining narrower ranges of processing values, it is apparent that the most influential process parameter depends on the levels considered. In particular, the holding time had the most effect on the RLT uniformity when embossing with the lower values of process parameters while, with higher processing settings, the molding temperature became the most influential factor.

scholarly journals Fabrication and Optical Characterization of Polymeric Aspherical Microlens Array Using Hot Embossing Technology

2021 ◽  
Vol 11 (2) ◽  
pp. 882
Author(s):  
Yanlong Li ◽  
Kangsen Li ◽  
Feng Gong
Keyword(s):  
Process Parameters ◽  
High Efficiency ◽  
Low Cost ◽  
Microlens Array ◽  
Hot Embossing ◽  
Molding Pressure ◽  
Microlens Arrays ◽  
Aspheric Lens ◽  
Molding Temperature ◽  
Holding Temperature

Hot embossing has been widely used in fabricating microlens arrays because of its low cost, high efficiency, and high quality. The process parameters such as molding temperature, molding pressure, and holding temperature affect the microlens array’s replication quality. This work selected the stainless steel S136H tool steel as the mold material to process an aspheric microlens array structure through ultra-precision milling. Polymethyl methacrylate (PMMA) microlens arrays with different surface replication were prepared by controlling the molding temperature, molding pressure, and holding temperature. By analyzing the surface quality, contour replication, and optical imaging of hot-embossed samples, the optimal molding temperature of PMMA for optimal replication of aspheric lens arrays was determined as 130 °C. Besides, the internal elastic recovery of PMMA affected the dimensional accuracy and optical performance of the lens. The results showed that, at the molding pressure of 400 N and the holding temperature of 60 °C, the surface defects were eliminated, and the aspheric lens array had perfect replication with a profile deviation of only 4 μm. The aspheric microlens array with good quality was eventually achieved by these optimal process parameters, which provides a foundation for producing aspheric microlens arrays in a low-cost and high-efficiency way.

Intestinal Bacteriology of Closed Loop, Strangulated Obstruction in Dogs.

1961 ◽  
Vol 41 (3) ◽  
pp. 245-250 ◽  
Author(s):  
George H. Bornside ◽  
Isidore Cohn
Keyword(s):  
Closed Loop
Sign in / Sign up

Export Citation Format

Share Document