Page 66 - Plastics News August - 2023

TECHNOLOGY

Fraunhofer Evaluates Density Determination Methods of Additively
Manufactured Parts
urement methods for density deter- nation works
mination in additive manufacturing” Philipp Pruesse of Dimensionics Den-
— the use of micrographs, computed sity described how the automated
tomography, and the manual Archi- density determination process works.
medes method were evaluated in ad- “Our process uses the Archimedes
dition to automated density determi- method mentioned above, but in
nation. combination with modern automa-
All of the methods are essentially ca- tion technology. The samples to be
pable of determining the relative den- measured are placed in a special com-
sity of AM parts, but the Fraunhofer ponent carrier, which is provided with
IAPT report found that there are sub- openings on the underside. These

Report notes that automated density stantial differences in accuracy, reso- component carriers are transported
determination developed by Dimen- lution, repeatability, and the possibility through the system by an axis robot
sionics Density excels in repeatability of defect detection. and, thus, lowered centrally and pre-
and traceability. Micrographs destroy the AM speci- cisely onto the scales. On the scales
themselves, a lift-out rack with pins
study comparing various density men. While they can provide partial is placed, which lifts the component
A measurement methods of parts insight into the actual condition of over the openings in the component
produced by additive manufacturing pores in a part, the process is charac- carrier, lifting it out of the carrier. The
(AM) commissioned by Germany’s terized by a lot of manual work, add- automated handling eliminates human
Fraunhofer IAPT has found that au- ing time and cost and relying on a high influence on the measurement, as the
tomated density determination de- degree of expertise, writes Dimen- parts are always placed identically
veloped by Dimensionics Density has sionics Density in the press release. onto the scales. The scales are de-
advantages in certain areas. Computed tomography (CT) also re- signed to be insulated from vibration.
Density determination of AM parts quires expertise. While it can provide In addition, all ambient conditions
can be critical because of its impact a realistic 3D image of the internal po- such as temperature, air pressure, and
on their structural integrity and per- rosity of a part, it is restricted in the water temperature, are recorded via
formance, according to Dimensionics pore size that it can detect. Moreover, climate sensors, and their influence
Density. It enables manufacturers to CT equipment can be prohibitively on the measurement result is taken
ensure part quality and reliability and expensive. into account directly in the evaluation
helps identify defects, porosity, and The Archimedes method is the easiest algorithm when determining the den-
voids within the material. Compared to use but can be the least accurate, sity,” said Pruesse.
with three other density determina- as the results can be affected by envi- The only traceable method
tion techniques, the method devel- ronmental conditions, the accuracy of
oped by Dimensionics Density is par- the balance, as well as the precision of The Fraunhofer IAPT benchmarking
ticularly recommended when density the experimental procedure. It is dif- report notes that Dimensionics Den-
evaluation has to be made quickly or ficult to reproduce the results, which sity’s automated density determina-
frequently, according to the Fraun- are strongly influenced by human fac- tion removes the user from the Archi-
hofer report. It also allows simplifica- tors, according to Dimensionics Den- medean measurement and, therefore,
tion of machine approvals, potentially sity. Test specimens are never placed has significantly higher repeatability
reducing quality assurance costs. exactly the same on the balance, and and fewer fluctuations. The report
also states that this method is the only
Comparison of four density deter- the manual operation of the balances one that is traceable, such that it can
mination methods leads to measurement deviations. be referenced to a recognized stand-
In the report — “Analysis of meas- How automated density determi- ard via a measurement chain.

66 PLASTICS NEWS August 2023
66 PLASTICS NEWS
August 2023