Bernd Löffler

Mr. Bernd Löffler

WZL of RWTH Aachen University
orcid

Research Focus & Metrics

Academic Career Length

7Years (2020-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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21 April 2022 in Polymers
Verified
Journal Article
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PFPeter Frohn-Sörensen
Peter Frohn-Sörensen
MGMichael Geueke
Michael Geueke
BEBernd Engel
Bernd Engel
Bernd LöfflerBernd Löffler
Bernd Löffler
PBPhilipp Bickendorf
Philipp Bickendorf
Günther SchuhGünther Schuh
Günther Schuh
In relation to the fourth industrial revolution, traditional manufacturing methods cannot serve the flexibility demands related to mass customization and small series production. Rapid tooling provided by generative manufacturing has been suggested recently in the context of metal forming. Due to the high loads applied during processes to such tooling, a purposeful mechanical description of the additively manufactured (AM) materials is crucial. Until now, a comprehensive characterization approach for AM polymers is required to allow a sophisticated layout of rapid tooling. In detail, information on compressive and flexural mechanical properties of solid infilled materials made by additive manufacturing are sparsely available. These elementary mechanical properties are evaluated in the present study. They result from material specimens additively manufactured in the fused filament fabrication (FFF) process. The design of the experiments reveals significant influences of the polymer and the layer height on the resulting flexural and compressive strength and modulus as well as density, hardness, and surface roughness. As a case study, these findings are applied to a cup drawing operation based on the strongest and weakest material and parameter combination. The obtained data and results are intended to guide future applications of direct polymer additive tooling. The presented case study illustrates such an application and shows the range of manufacturing quality achievable within the materials and user settings for 3D printing.

Verified
Journal Article
Open access
PDF file
Georg BergweilerGeorg Bergweiler
Georg Bergweiler
FFFalko Fiedler
Falko Fiedler
Ahsan ShaukatAhsan Shaukat
Ahsan Shaukat
Bernd LöfflerBernd Löffler
Bernd Löffler
While deep drawing of sheet metals is economical at high volumes, it can be very costly for manufacturing prototypes, mainly due to high tooling costs. Additively manufactured polymer tools have the potential to be more cost-efficient for small series, but they are softer and thus less resilient than conventional steel tools. This work aimed to study the dimensional precision of such tools using a standard cup geometry. Tools were printed with FFF using two different materials, PLA and CF-PA. A test series of 20 parts was drawn from each tool. Afterwards, the dimensional precisions of the drawn parts were analyzed using an optical measuring system. The achieved dimensional accuracy of the first drawn cup using the PLA toolset was 1.98 mm, which was further improved to 1.04 mm by altering shrinkage and springback allowances. The repeatability of the deep drawing process for the CF-reinforced PA tool was 0.17 mm during 20 drawing operations and better than that of the PLA tool (1.17 mm). To conclude, deep drawing of standard cups is doable using direct polymer additive tooling with a dimensional accuracy of 1.04 mm, which can be further improved by refining allowances incorporated to the CAD model being printed.