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Journal PROCEEDINGS IN MANUFACTURING SYSTEMS |
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ISSN 2343–7472 ISSN-L 2067-9238 |
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Journal PROCEEDINGS IN MANUFACTURING SYSTEMS □
Volume 20, Issue 2, 2025 Additive
manufacturing of pneumatically actuated soft robotic grippers: enabling complex geometries and configurations Comparative analysis of defects occurring in the layers of 3D-printed plastic parts using the FDM Technology · Cristian Ionel PĂUNESCU, Alexandru Ștefan VELICU, Marius MOCANU, Sustainable
budgeting of maintenance activities using technical indicators · Cozmin CRISTOIU, Mario IVAN, Marius Valentin DRAGOI, Emilia POPESCU, Roxana NECHITA Method for
qualitative evaluation of robotic trajectories based on geometric and
kinematic metrics New inexpensive Ti‒Mn‒Fe
alloys for medical applications Additive manufacturing of pneumatically actuated soft robotic
grippers: enabling complex geometries and configurations Dragoș-Alexandru CAZACU1,*, Delia GHEORGHE-NĂFTĂILĂ2, Mihail HANGA3, Carmen-Cristiana CAZACU4, Florina CHISCOP4 1) Eng., PhD Student, Education Team, PTC Eastern
Europe SRL, Bucharest, Romania, 2) PhD Student, Industrial Engineering and Robotics
Fac., National University of Science and Technology POLITEHNICA Bucharest,
Romania, 3) Master Student, Industrial Engineering and Robotics
Fac., National University of Science and Technology POLITEHNICA Bucharest,
Romania, 4) Lecturer, PhD, Robots and Manufacturing Systems
Dep., National University of Science and Technology POLITEHNICA Bucharest,
Romania Abstract: This paper presents the design,
fabrication, and testing of a pneumatically actuated soft gripper
manufactured via multimaterial 3D printing (FDM), combining flexible TPU 40D
segments with PLA structural elements for stiffening and modular assembly.
The biomimetic geometry – drawing inspiration from the segmented locomotion
of caterpillars – integrates three “fingers” with internal pneumatic channels
and partially fused chambers, optimized to deliver controlled elastic
deformation while meeting AM design constraints (minimum wall thicknesses,
overhang angles ≥ 45°, and avoidance of long unsupported bridges). The
fabrication strategy included mid-print PLA inserts for anchoring,
sliding-fit gaps of 0.05–0.15 mm, and a teardrop-shaped internal channel to
minimize unsupported spans and improve process repeatability. Preliminary
tests showed (i) a smooth and predictable bending response of a single finger
at ≈ 1–3 bar, validating the material choice and chamber configuration,
and (ii) reduced performance of the three-finger assembly due to air leaks at
the interfaces, underscoring the importance of sealing and robust pneumatic
distribution. Improvement directions include the use of O-rings/gaskets, fine
pressure regulation, and integration of sensors for closed-loop control. The
results indicate that 3D-printed soft grippers can combine adaptability,
customization, and cost efficiency for delicate manipulation, paving the way
for industrial and medical applications where safe interaction with fragile
objects is critical. Key words: additive manufacturing, robotics,
pneumatics, thermoplastic polyurethane, soft grippers. Comparative analysis of defects occurring in the layers of 3D-printed plastic parts using the FDM technology Vasilica Cristina ICOCIU1, Nicoleta-Elisabeta PASCU2,*, Tiberiu DOBRESCU2, Ionuţ Cristian PEREDERIC3, Patricia Isabela BRĂILEANU1 1) Assoc. Prof., PhD, Department of Robots and
Manufacturing Systems, National University of Science and Technology
POLITEHNICA Bucharest 2) Prof., PhD, Department of Robots and Manufacturing
Systems, National University of Science and Technology POLITEHNICA Bucharest 3) Assistant Prof.,
PhD Student, Department of Robots and Manufacturing Systems, National
University of Science and Technology POLITEHNICA Bucharest Abstract: The 3D printing process can be significantly improved by understanding the behavior of materials during printing, highlighting the differences in their physical and chemical properties. This understanding allows an analysis of the defects that appear between successively deposited layers, with the aim of reducing them or, in the best case, eliminating them completely. The elimination of these defects naturally leads to an increase in fracture resistance and, consequently, the durability of 3D-printed parts. This article analyzes the common defects that occur between the layers of plastic materials. The plastic materials examined in this study are Acrylonitrile Butadiene Styrene (ABS), Polylactic Acid (PLA), Polyethylene Terephthalate Glycol (PETG), Thermoplastic Polyurethane (TPU), and Nylon. Depending on the material used and the optimized printing process parameters, the defects between layers can vary significantly or may have similar causes. The most common defects analyzed in this study are poor adhesion of the first layer, weak adhesion between successive layers, and the occurrence of the warping phenomenon. The main objective of the paper focuses on analyzing these defects, understanding their causes, and proposing solutions for their prevention and correction. The discussions in this analysis will focus on the behavior of these materials in relation with the defects that may occur. Key words: plastic materials, 3D printing, layer deposition, defects, prevention, improvement. Sustainable budgeting of maintenance activities using technical
indicators Cristian Ionel PĂUNESCU1, *, Marius MOCANU2, Alexandru Ștefan VELICU3 1,2) PhD Student, Robots and
Manufacturing Systems Department, National University of
Science and Technology POLITEHNICA Bucharest, Romania 3) Lecturer, PhD, Automatic Control and Computer
Science Department, National
University of Science and Technology POLITEHNICA Bucharest, Romania Abstract: The research presented in this paper is materialized by applying a method for maintenance activity that takes into account the technical efficiency indicators of the equipment. The control of the maintenance expenses to be budgeted is enabled by the adaptive character of these indicators which characterize the path of the previous productive process of the equipment. This paper analyzes ‒ as a case study ‒ the effects of using the budgeting method based on assets technical indicators and the price-per-product reporting index (between the past and present period for one year). The method is applied for the maintenance works needed to keep in good operation condition a concrete pipe pushing machine run by the company SC SOPMET SA. It is demonstrated that the application of this adaptive method to budget formulation stabilizes significantly the expenses level in maintenance activity. Key words: budget based on technical indicators,
safety margins, budgetary responsibilities. Method for qualitative evaluation of robotic trajectories based on geometric and kinematic metrics Cozmin CRISTOIU1,*, Mario IVAN2, Marius Valentin DRAGOI3, Emilia POPESCU4, Roxana NECHITA5 1), 2), 3), 4) Lecturer, PhD, Robots and
Manufacturing Systems Dep., National University of Science and Technology POLITEHNICA
Bucharest, Romania 5) Research Eng., Biomedical Mechatronics and Robotics
Dep., National Institute of Research and Development in Mechatronics
and Measurement Technique, Bucharest, Romania Abstract: This paper presents a quantitative
framework for the qualitative evaluation of robotic trajectories based on
geometric and kinematic metrics. While trajectory optimization in industrial
robotics is often judged visually or through execution time, such criteria
may overlook aspects of motion smoothness and stability. Starting from a set of ten
randomly distributed target points, several alternative trajectories with
similar total lengths were generated using cubic spline interpolation through
different intermediate points. For each trajectory, specific evaluation
metrics were computed, including total path length, mean and maximum
curvature, jerk-based smoothness indices, and a composite quality score. The obtained values were compared and
analyzed to identify correlations between the proposed metrics and the
robot’s simulated motion in RoboDK. Results show that even trajectories of
comparable length can exhibit significantly different curvature and jerk
characteristics, directly influencing execution quality. The proposed
metric-based approach enables an objective assessment of trajectory quality
and provides a foundation for advanced optimization strategies grounded in
physical or data-driven principles. Key words: robotics, trajectory, kinematics,
curvature, metrics. New
inexpensive Ti‒Mn‒Fe alloys for medical applications Clara Mihaela SOARE1,*, Alexandra Mihaela TUDOR2, Julia Claudia MIRZA-ROSCA2, Victor GEANTA3, Ionelia VOICULESCU4 1, 2) PhD Student, Doctoral School of Industrial Engineering and Robotics,
National University of Science and Technology POLITEHNICA Bucharest, Romania 2) Prof., PhD, Department of Mechanical Engineering, University of Las
Palmas de Gran Canaria, Las Palmas, Spain 3) Prof., PhD, Department of Engineering and Management of Metallic
Materials Obtainment, Faculty of Science and Engineering of Materials,
National University of Science and Technology POLITEHNICA Bucharest, Romania 4) Prof., PhD, Department of Quality Engineering and Industrial
Technology, Faculty of Industrial Engineering and Robotics, National
University of Science and Technology POLITEHNICA Bucharest, Romania Abstract: The
paper presents the criteria for the design, production and characterization of
new low-cost Ti‒Mn and Ti‒Fe alloys, intended for the manufacture
of biomedical devices. To obtain these low-cost alloys, a commercial alloy Ti‒6Al‒4V
is used, resulting from mechanical processing, to which alloying elements
considered biocompatible, such as Fe and Mn, are added. The addition of Mn
and Fe aims at stabilizing the β phase of Ti and microstructural
refinement, with the aim of improving mechanical performance, while
maintaining a low elastic modulus, close to that of human bone. The alloys are
obtained by vacuum arc melting under argon protection. Mn and Fe are added in
the form of granules with a purity of 99.5%, obtaining the Ti‒3Mn
alloy, with a low Fe content, and Ti‒5Fe, with a low Mn content. After
melting together, using high purity raw materials (over 99.5%), the
concentrations of highly toxic alloying elements, such as V and Al, are
reduced. The chemical concentrations of the obtained alloys are determined by
X-ray spectrometric analysis, and the examination of the obtained microstructures
is performed by optical and scanning electron microscopy. It is found that
the Ti‒Mn and Ti‒Fe alloys exhibit homogeneous lamellar
microstructures of α + β phases and an improved hardness compared
to commercial pure titanium or Ti‒6Al‒4V-type alloys. Such
properties indicate a strong potential for their use in the fabrication of
biomedical components, particularly orthopaedic and dental implants. Key
words: Ti‒Mn‒Fe
alloys, biocompatibility, microstructure, microhardness. |
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