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Plastics engineering

Project "Hot Gas Welding"

Project "Hot Gas Welding" (completed)

In this research project a new hot gas welding process is being developed and scientifically investigated. The new hot gas welding process has several advantages over currently used welding methods. These are especially in the free design of the weld seam and its course. Three-dimensional weld seams can be produced very easily in comparison to the usual welding methods, such as ultrasonic or vibration welding. In addition, this welding process does not produce any particles which could lead to system damage in the later operation of the components.

The new hot gas welding process is also expected to significantly increase resource efficiency by using air instead of an inert gas. The influence of the gas exchange on the welded joint as well as the targeted, uniform heating of the plastic component in the area of the joining zone is to be investigated. For this purpose, the gas flow and nozzle design must be considered in particular to ensure a fast and uniform heating of the joining zone. Based on the results, design strategies for hot gas mirrors and corresponding component design are to be derived. The resource efficiency of the new welding process is to be confirmed by considering the sustainability.


Duration: April 2019 - December 2021
Project partner: GMB Kunststoffteile GmbH
Funding sign: ZF4166303FH8
Project Management Agency: AiF Projekt GmbH, ZIM-Cooperation Projects
Contact persons: Prof. Dr.-Ing. Matthias Deckert, Johannes Schmid, M.Sc.

 

Selection of publications within the framework of the project:

Project "Hot Gas Welding II"

Project "Hot Gas Welding II"

Project title: Increasing the strength for a resource-efficient hot gas welding process through a new type of hot gas nozzle and through a new type of joining movement.

In a previous research project between GMB Kunststoffteile GmbH and the Department of Plastics Technology (LKT) - Faculty of Machines and Systems at Esslingen University of Applied Sciences (funding reference: ZF4166303FH8), a new kind of nozzle for hot gas welding of plastics was developed [DE 20 2021 101 884 U1 - utility model specification: Device for welding plastic parts]. One advantage of the non-contact welding process (hot gas welding) is, among other things, that no particles are produced which could lead to system damage during subsequent operation of the components. This new type of top nozzle has a number of advantages over the round nozzles currently in use. For example, the joining zone can be heated much faster and more evenly.
In the new research project, the top nozzle system is to be further developed so that it is possible to heat three-dimensional welding seams more evenly. The influence of the new top nozzle on the welded joint is to be researched, as well as the targeted, uniform heating of the plastic component in the area of the joining zone. Another point in the research project is the further development of the joining movement. In order to significantly improve the economic efficiency of hot gas welding and to open up new fields of application, the aim is to increase the strength of the joined components at the weld seam. Here, a joining movement during the welding process is to be integrated into the process by means of a robot-based approach in order to improve the weld seam strength. In addition, the further development of the top nozzle should make it possible to weld strength-inhibiting geometries such as edges or radii much better and, through targeted gas guidance, three-dimensional seam courses should also become weldable. This will make it possible to further improve the seam strength. Due to a higher weld seam strength, the component can be designed with thinner walls. Overall, there are significantly more options available in the component design due to a lower strength drop in the joint. Therefore, the need for a new hot gas nozzle concept and a new type of joining movement is high.

 

Duration: September 2021 until August 2023
Project partner: GMB Kunststoffteile GmbH, robomotion GmbH, TU Chemnitz - Department of Lightweight Structures and Polymer Technology
Funding sign: KK5052604WO0
Project Management Agency: AiF Projekt GmbH, ZIM-Cooperation Projects
Contact persons: Prof. Dr.-Ing. Matthias Deckert, Johannes Schmid, M.Sc.

 

Selection of publications within the framework of the project:

Projekt "Snake Skin"

Projekt "Snake Skin" (completed)

The aim of the project, which is being jointly applied for by the Esslingen University of Applied Sciences and the Fraunhofer Institute for Mechanics of Materials IWM, is to develop industrial manufacturing processes for the production of bio-inspired nanostructures with high durability on polymer surfaces with a direction-dependent coefficient of friction (coefficient of friction on demand) that can be freely adjusted over a wide range and in line with requirements. Possible applications include the fields of medical and microsystems technology as well as storage and conveyor technology. Both small and large surfaces can be structured and thus functionalized in the desired injection molding process. In order to achieve this goal, processes for PVD-based, large-area deposition of directed (anisotropic) nanostructures are to be developed in the project. Such structures are to be applied to tools for plastic injection molding and molded into crosslinking polymers in the injection molding process so that structures modelled on the California King Snake can be created on the polymer surface. The skin of the King Snake has a special anisotropic micro- and nanostructure that allows the snake to move safely even on the most difficult surfaces. The tool surface can be flat or slightly curved and the surface can already have a microstructure introduced by conventional processing methods. The application of anisotropic nanostructures is to be achieved by an adapted process control in the coating process and by exploiting self-organization effects in the layer growth. In the injection molding process, it is to be investigated how the structures on the tool surfaces can be transferred to the component surfaces by means of targeted process control and how they can be reliably demolded. For increased durability, the nanostructures are to be molded in Liquid Silicone Rubber (LSR), a silicone suitable for injection molding. Variothermal temperature control is used for optimized replication. In contrast to the processing of thermoplastics, the mold surface is actively cooled before injection.

In the course of the project, such nanostructured demonstrator components will be sampled and characterized with respect to their friction coefficient properties and resistance. This is intended to provide evidence of the anisotropic, tribological effect of nanostructures and thus the targeted, direction-dependent friction coefficient modification. In the future, improved instruments for minimally invasive surgery, for example, will be available that will provide the surgeon with significantly improved haptic feedback compared to existing solutions. A further application is seen in conveyor technology, where direction-dependent and low-wear surfaces can be used, e.g. in vibrating spiral conveyors.

 

Duration: October 2018 - December 2021
Project partner: Fraunhofer Institute for Mechanics of Materials
Project sponsor: VDI Technology Center, Project sponsor of the Baden-Württemberg Foundation
Contact persons: Prof. Dr.-Ing. Matthias Deckert, Dennis Weißer, M.Sc. 

 

Publication:

Project "Adhesion of LSR"

Project "Adhesion of LSR" (completed)

During the research project the influence of the injection molding process on the bond strength of liquid silicone rubber (LSR) to thermoplastics is investigated. For this purpose, the mechanisms that are decisive for the bond strength will first be described and implemented in an empirical formula. Thus, already during the design phase the right material should be selected and the achievable bond strength should be specified.

The established model shall then be verified. For this purpose, an injection mold is to be designed and built that can process both materials and allows a detailed investigation. Especially the temperature control has to be considered more closely, since both materials are processed at very different mould temperatures. For this purpose a novel temperature control system based on a thick film heating element will be used. With this heating element, the temperature can be changed quickly, selectively and also during the injection molding process.

Duration: March 2019 - December 2021
project partners: Wilhelm Weber GmbH & Co. KG
funding sign: ZF4166302DN8
Project Management Agency: AiF Projekt GmbH, ZIM-Cooperation Projects
Contact persons: Prof. Dr.-Ing. Matthias Deckert, Dennis Mayer, M.Eng.

Projekt Snake Skin Conveyor

Projekt Snake Skin Conveyor

SnakeskinConveyor: Development of injection-molded, bionically microstructured plastic plates with structure widths of approx. 1 µm, based on an anisotropic snakeskin structure, as a conveying surface covering for vibratory conveyors.

The aim of the research project is to develop microstructured plastic sheets with anisotropic friction values based on snakeskin in the dimensions 100 x 100 mm, which enable targeted conveying. The microstructure is to be applied to one side of the plate surface by means of an injection molding process and have structure widths of 1 µm. To this end, snakeskins are being researched and adapted as a CAD model for surface mapping with a tolerance accuracy of ±200 nm. In addition, an injection molding tool with mold inserts will be developed using laser structuring. The injection molding process will be designed variothermally to achieve a molding accuracy of >99 % and to prevent solidification of the plastic in the peripheral area. For this purpose, a thermal design of the near-contour temperature control of the mold surface is being developed, with which temperature change rates of up to 100 K/s at process pressures of up to 2000 bar can be achieved. Finally, a bonding concept is developed to achieve a shear strength of >20 MPa and a peel strength of >50 N/cm. The market potential is very high in Germany with a turnover of €16.5 billion in materials handling technology.

 

Duration: July 2022 - June 2024
Project partners: VIBROTEC Aktiengesellschaft AG; POLY-TOOLS bennewart GmbH
Funding code: KK5052611CD1
Project executing organization: AiF Projekt GmbH, ZIM Cooperation Projects.
Contact person: Prof. Dr.-Ing. Matthias Deckert, Dennis Mayer, M.Eng.

Projekt Nano Tool

Projekt Nano Tool

NanoTool: Development of a 3D model with water- and dirt-repellent nanostructure with contact angles >160°, development of a method for researching dirt-repellent properties of nanostructures and researching component properties.

The project objective is the development of a water- and dirt-repellent nanosurface, which is to be engraved for the first time as a negative into the insides of injection mold (SGW) mold insides by means of picolaser in order to produce individual workpieces (e.g. ABS, TP, TPE) with self-cleaning properties. For this purpose, superhydrophobic (contact angle > 160°) surfaces (e.g. lotus flower or cicada wing) will be researched and a 3D model developed on them. Using a high-precision (accuracy< 1 µm) laser micromachining machine, a process is to be developed to engrave this nanostructure with an agreement of > 99 % on the inside of the mold, which will then be inserted into a specially developed injection molding tool with near-contour temperature control. By means of the novel temperature control system, the injection mold will enable a homogeneous (+/- 1 °C) injection temperature and a heating rate of up to 60 K/s. The new variothermal temperature control system will be used for this purpose. For this purpose, a new variothermal process control will be developed to ensure a moldability of > 95% of the nanostructure onto the workpiece. The resulting workpieces should exhibit water- and dirt-repellent properties over the entire product life cycle (> 5 years).

 

Duration: July 2022 - June 2024
Project partners: LMB Kunststofftechnik GmbH; Laser-Mikrotechnologie Dr. Kieburg GmbH
Funding code: KK5052610 FF1
Project Management Agency: AiF Projekt GmbH, ZIM Cooperation Projects
Contact person: Prof. Dr.-Ing. Matthias Deckert, Dennis Weißer, M.Sc. 

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