In-vacuum silicone rubber forming process for soft robots

Abstract Silicone rubber is widely used in various soft robots, sensors, and actuators. One of the most popular fabrication processes for silicone rubber is molding, which can easily duplicate three-dimensional (3D) shapes using a mold. Among the molding techniques, vacuum molding is a useful approa...

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Main Authors: Yuta Ishikawa, Hiroyuki Nabae, Gen Endo, Koichi Suzumori
Format: Article
Language:English
Published: SpringerOpen 2025-04-01
Series:ROBOMECH Journal
Subjects:
Online Access:https://doi.org/10.1186/s40648-025-00296-4
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author Yuta Ishikawa
Hiroyuki Nabae
Gen Endo
Koichi Suzumori
author_facet Yuta Ishikawa
Hiroyuki Nabae
Gen Endo
Koichi Suzumori
author_sort Yuta Ishikawa
collection DOAJ
description Abstract Silicone rubber is widely used in various soft robots, sensors, and actuators. One of the most popular fabrication processes for silicone rubber is molding, which can easily duplicate three-dimensional (3D) shapes using a mold. Among the molding techniques, vacuum molding is a useful approach for preventing defects in molded parts. However, during the vacuum molding process, handling objects in a vacuum is challenging, requiring the mold to be carefully designed to prevent air bubble entrapment without manipulating the silicone rubber pouring point or the mold. In this study, to address these challenges, we propose an in-vacuum silicone rubber forming process. This process allows the silicone rubber pouring point to be controlled in a vacuum using a five-bar parallel link manipulator. This manipulator can be easily installed with only two rotational rods, typically employed as mixing rods within the chamber, facilitating efficient molding processes such as multi-part fabrication with minimal silicone rubber waste without the need for special mold designs. We validate the effectiveness of this process by molding cylindrical structures with diameters ranging from 1.2 to 5 mm and three types of liquid silicone rubbers with viscosities from 3 to 20 $$\text{Pa}\cdot \text{s}$$ Pa · s . Compared to conventional methods—standard molding and vacuum molding, our proposed approach could successfully mold all cylinders without voids or air bubbles. Additionally, the applicability of this method to soft robotics was demonstrated through two applications using major soft actuators, pneumatic actuator and dielectric elastomer actuator (Non-standard abbreviation: DEA—Dielectric Elastomer Actuator), for soft robotics.
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spelling doaj-art-ef5cc7f1cd104cb594b52ca603fdb4c82025-08-20T03:07:43ZengSpringerOpenROBOMECH Journal2197-42252025-04-0112111310.1186/s40648-025-00296-4In-vacuum silicone rubber forming process for soft robotsYuta Ishikawa0Hiroyuki Nabae1Gen Endo2Koichi Suzumori3Department of Mechanical Engineering, Institute of Science TokyoDepartment of Mechanical Engineering, Institute of Science TokyoDepartment of Mechanical Engineering, Institute of Science TokyoDepartment of Mechanical Engineering, Institute of Science TokyoAbstract Silicone rubber is widely used in various soft robots, sensors, and actuators. One of the most popular fabrication processes for silicone rubber is molding, which can easily duplicate three-dimensional (3D) shapes using a mold. Among the molding techniques, vacuum molding is a useful approach for preventing defects in molded parts. However, during the vacuum molding process, handling objects in a vacuum is challenging, requiring the mold to be carefully designed to prevent air bubble entrapment without manipulating the silicone rubber pouring point or the mold. In this study, to address these challenges, we propose an in-vacuum silicone rubber forming process. This process allows the silicone rubber pouring point to be controlled in a vacuum using a five-bar parallel link manipulator. This manipulator can be easily installed with only two rotational rods, typically employed as mixing rods within the chamber, facilitating efficient molding processes such as multi-part fabrication with minimal silicone rubber waste without the need for special mold designs. We validate the effectiveness of this process by molding cylindrical structures with diameters ranging from 1.2 to 5 mm and three types of liquid silicone rubbers with viscosities from 3 to 20 $$\text{Pa}\cdot \text{s}$$ Pa · s . Compared to conventional methods—standard molding and vacuum molding, our proposed approach could successfully mold all cylinders without voids or air bubbles. Additionally, the applicability of this method to soft robotics was demonstrated through two applications using major soft actuators, pneumatic actuator and dielectric elastomer actuator (Non-standard abbreviation: DEA—Dielectric Elastomer Actuator), for soft robotics.https://doi.org/10.1186/s40648-025-00296-4Vacuum moldingSoft roboticsFive-bar parallel link manipulatorMolding defects
spellingShingle Yuta Ishikawa
Hiroyuki Nabae
Gen Endo
Koichi Suzumori
In-vacuum silicone rubber forming process for soft robots
ROBOMECH Journal
Vacuum molding
Soft robotics
Five-bar parallel link manipulator
Molding defects
title In-vacuum silicone rubber forming process for soft robots
title_full In-vacuum silicone rubber forming process for soft robots
title_fullStr In-vacuum silicone rubber forming process for soft robots
title_full_unstemmed In-vacuum silicone rubber forming process for soft robots
title_short In-vacuum silicone rubber forming process for soft robots
title_sort in vacuum silicone rubber forming process for soft robots
topic Vacuum molding
Soft robotics
Five-bar parallel link manipulator
Molding defects
url https://doi.org/10.1186/s40648-025-00296-4
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AT hiroyukinabae invacuumsiliconerubberformingprocessforsoftrobots
AT genendo invacuumsiliconerubberformingprocessforsoftrobots
AT koichisuzumori invacuumsiliconerubberformingprocessforsoftrobots