Fused deposition modelling (FDM) 3D printers have the highest annual growth of 21.15% in the field of 3D printing. FDM desktop 3D printers account for 23.69% of FDM printers. The major drawback of FDM desktop printers is product accuracy, which is particularly pronounced when dimensionally inaccurate and multi-part printed products need to be fit together into a functional assembly. The research presented in this paper aims to determine the accuracy limits of FDM 3D printers when producing elements for assembly using a 3D printer in a tolerance-fit system. A novel method of computer-aided design (CAD) based on ISO 286 and the systematic calibration procedure of 3D printers were presented to achieve the dimensional accuracy of 3D printed parts. For this purpose, a set of nominal dimensions within the clearance fit was selected, and various CAD models were created according to the ISO 286 system of limits and fits. The CAD Slicer software–3D printer interaction was systematically examined for the best hardware and software features. It was found that the Horizontal Expansion parameter should be 0.0 mm and the Hole Horizontal Expansion parameter should be 0.13 mm. The Linear Advance factor was found to be 25. The measurement results showed that the desired tolerance ranges, system, and type of clearance fit could be achieved with a desktop 3D printer. The roundness tolerance for all clearance fits and shaft tolerance ranges in the hole base system was determined to join the parts into a clearance fit.

Recent soft tissue studies have reported issues that occur during experimentation, such as the tissue slipping and rupturing during tensile loads, the lack of standard testing procedure and equipment, the necessity for existing laboratory equipment adaptation, etc. To overcome such issues and fulfil the need for the determination of the biomechanical properties of the human gracilis and the superficial third of the quadriceps tendons, 3D printed clamps with metric thread profile-based geometry were developed. The clamps’ geometry consists of a truncated pyramid pattern, which prevents the tendons from slipping and rupturing. The use of the thread application in the design of the clamp could be used in standard clamping development procedures, unlike in previously custom-made clamps. Fused deposition modeling (FDM) was used as a 3D printing technique, together with polylactic acid (PLA), which was used as a material for clamp printing. The design was confirmed and the experiments were conducted by using porcine and human tendons. The findings justify the usage of 3D printing technology for parts manufacturing in the case of tissue testing and establish independence from the existing machine clamp system, since it was possible to print clamps for each prepared specimen and thus reduce the time for experiment setup.

The purpose of this research was to analyze the applicability of infrared thermography in assessing the condition of an e-bike battery. The main challenge was to interpret the surface radiation detected by a thermal imaging camera. In addition to basic challenges of thermography, such as determining the emissivity, the angle of image acquisition, the problem of low resolution and thermal inertia, it was necessary to understand the physical behavior of the elements inside the battery and battery pack that respectively determine the dynamics and shape of the thermal pattern. E-bike batteries are mainly composed of 18650 format Li-ion cells, and the topology of the battery cell is related to the energy profile of the system. With the aim of establishing a link between the surface radiation patterns and the parameters of the individual 18650 cells that dictate the internal thermal behavior, a detailed analysis of the battery pack interior, upon its lifetime, was performed. Based on the results of the capacity analysis of the individual cells and determination of the exact position of the cells within the structure of the battery, a visualization and comparison with the thermographic records were performed to determine whether infrared thermography is able to diversify faulty cells. The conclusion of the study is that it is not possible to make a judgment about the thermal pattern expression or the pattern shape based on the estimated capacity values; however, based on the pattern, it is possible to draw a conclusion about the homogeneity of the capacity of the individual battery cells.

The lack of standardization in tissue testing procedures results in a variety of custom-made devices. In the case of the determination of the mechanical properties of tendons, it is sometimes necessary to adapt the existing laboratory equipment for conducting experiments when specific commercial equipment is not applicable to solve issues such as proper gripping to prevent tendon slipping and rupturing, gripping control and manoeuvrability in case of tendon submerging and without contamination of the testing liquid. This paper presents the systematic development, design, and fabrication using 3D printing technology and the application of the double-acting linear pneumatic actuator to overcome such issues. It is designed to do its work submerged in the Ringers’ solution while gripping the tendon along with the clamps. The pneumatic foot valve unit of the Shimadzu AGS-X tensile testing machine controls the actuator thus preventing Ringers’ solution to be contaminated by the machine operator during specimen set-up. The actuator has a length of 60 mm, a bore of 50 mm, and a stroke length of 20 mm. It is designed to operate with an inlet pressure of up to 0.8 MPa. It comprises the cylinder body with the integrated thread, the piston, the piston head, and the gripper jaw. Fused deposition modeling (FDM) has been used as the 3D printing technique, along with polylactic acid (PLA) as the material for 3D printing. The 3D printed double-acting linear pneumatic actuator was developed into an operating prototype. This study could open new frontiers in the field of tissue testing and the development of similar specialized devices for medical purposes.

One of the main quality characteristics of cereals, especially wheat is its hardness which is closely related with grain’s vitreosity, one of the main quality indicators of a variety. Determination of vitreosity is usually done visually: namely, after the grain is cut with a commercially available grain-cutters, the cut can result in broken or crushed grains which disables the reading and hinders the precision and accuracy. Also, the moment produced from the manual force on the grain-cutter crank, needed to cut the sample of cca. 50 grains placed in the cutter is an average of 30 Nm. Due to the resistance of the grain, yank force appears. This force can cause the whole instrument to be displaced during cutting. To minimize the errors using a commercially available cutter, a new knife/blade has been implemented and tested. The blade of the new knife is turned at the inclination angle of 49° in relation to the cutting objects (grains). This design solution enables achievement of the grain “cutting”, not grain “tearing”, as observed with the existing commercial design solution. With the proposed new design solution, amount of the moment is reduced to 2.72 Nm and the yank force is completely avoided. Also, a significantly lower amount of the cutting force, on the knife blade is achieved. The results obtained with the new knife gave a better read, were more precise, and the gadget was easier to operate since it demanded lower force to cut the grains. The novelty introduced by this research provided better and more reliable insight into determining the vitreousness of grains. Providing a clearer cut and better readability, this solution goes beyond the current literature by reducing the force required for analysis and speeding up the analysis process.

Knowledge of the dynamic properties of thermometers is of particular importance for successful automation of process management in real time. The dynamic behaviour, i.e. the thermal response of the thermometers, is primarily determined by the thermal time constants of the thermo sensor and the protective housing in which it is located (thermo immersion probe, thermowell). In this paper, we presented a simple, but for a large number of applications acceptably accurate method of determining the thermal time constants of the temperature sensor. The procedure for determining the thermal time constants of a thermometer is shown on the example of a thermometer with a resistance temperature sensor. The paper presents the thermal model of the resistance temperature sensor and the protective housing of the sensor. By suddenly immersing the immersion probe in a container with heated water, the temperature response was recorded. Based on the presented thermal model, the thermal time constants of the temperature sensor and the protective case were determined.