Development of a reliable spring-based connection technology for digitally manufactured lead structures
Duration: 09/01/2021 – 08/31/2023
The project aims to develop an industrially suitable, spring-based contact element as well as user-friendly design guidelines for it. The final result is a calculation tool that allows companies to design contact elements for printed conductive structures based on defined requirements.
The social trends towards increased functionality and individualised products result in major challenges for production in terms of function compression and simultaneous flexibilisation. Printing electronics offers a solution to this. With this additive manufacturing technology, conductive pastes and inks can be applied flexibly and in variable locations to planar or three-dimensional surfaces without additional tooling, stencilling or assembly effort. Depending on the pattern applied, functional elements such as conductive tracks, sensors, antennas, heating elements or actuators can be realised.
At present, the still unreliable contacting prevents the printed functional elements from being used in industrial series production in applications that are subject to high mechanical stress, as is often the case in the automotive, aerospace, sports and medical technology sectors. On the one hand, there is a lack of suitable contacting methods for the printed structures and, on the other, a design system based on defined requirements.
Economic significance of the targeted research results for SMEs
The global market for printed electronics is currently $7.8 billion. By 2025, this is expected to reach $20.7 billion, representing an annual growth rate of 21.5%. The increasing demand for flexible electronics at low manufacturing costs and the need for environmentally friendly technologies are paving the way for the increasing use of printed functional elements. Application industries for functional printing are broadly diversified, but can basically be assigned to two classes.
Functionalisation of individual products
e.g. printed power lines, analogous to the “3D-printed house”.
- Mechanical and plant engineering
e.g. strain sensors for load detection
- Medical products
e.g. active prostheses
- Sports equipment
e.g. sensory ski roller
Making mass production more flexible
- Retail and packaging
e.g. concealed seal to determine the authenticity of a product
e.g. heating elements without carrier foil on wing elements for de-icing
- Automotive and transport (cars, trucks)
e.g. functionalised bumper
For industries with a focus on individual products, functional printing is an enabler for the production of function-integrated systems and in some cases has no alternative in terms of mass and installation space. Digitally controlled processes make it economically feasible to manufacture up to a quantity of 1, as only web or layout adjustments have to be made for the next product. It is therefore possible to take into account the customer-specific geometries of the components and at the same time to realise customer-specific properties (sensors, actuators) by means of functional printing.
In mass production, the motivation of functional printing is to make production lines more flexible and to use them as needed. In the automotive industry in particular, there is considerable potential for savings through functional printing, for example by replacing cable harnesses. On the one hand, the variety of variants and the length of cable harnesses is increasing dramatically. This trend will increase even more in the future due to autonomously driving vehicles and redundantly designed systems. On the other hand, the proportion of manual work in the production of cable harnesses is still very high at 80% and can hardly be automated, as cables are usually flexible. In addition, the assembly of the cable harnesses is done manually. The total labour costs for the production of a vehicle amount to 10%. This proportion can be reduced by digitally manufactured control structures. At the same time, they offer a solution for the increasing complexity of cable harnesses.
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Fraunhofer-Institut für Werkzeugmaschinen und Umformtechnik (IWU)