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The demand for coronary artery stents keeps rising every year with a higher quality, lower cost, faster and economical process. Due to its availability relatively low-cost price and adaptability, Polylactic-acid (PLA) has been identified as an ideal material for biodegradable stents. Previously, laser micromachining was widely used for processing coronary stent but this manufacturing process required high investment. Apart from that, this process was unpractical and unfeasible to be machined with certain material and complex design. Alternatively, FDM 3D printing emerges as a system for producing stent and gained attention for its low cost, high reliability, simple operation, flexibility and has shown potential as promising solutions in stents fabrication. Stent length is one of the key aspects in stents manufacturing. In this work, optical microscope is used to measure the stent characterizations while processing parameter optimization was performed by using Response Surface Methodology (RSM). Printing orientation affects the stent length dimensional accuracy. Both XY and ZX are capable to develop PLA stents but XY-orientation is the ideal printing orientation as it provides good dimensional precision for stent characterizations and a lower risk for the structure and geometry to be sagging.

This work presents printing parameter optimization of 3D printed biodegradable PLA stent. This study is motivated by a gap in current knowledge in 3D printing of stents identified in an extensive literature review. With the demand of coronary artery stents rising every year, the stent production demands a higher quality, lower cost, faster and economical process. Due to its availability relatively low-cost price and adaptability, PLA has been identified for an ideal material for biodegradable stents. Previously, laser micromachining was widely used for processing coronary stent. The emerging of 3D printing process has gained attention for its low cost, high reliability, simple operation and flexibility has shown potential as promising solutions in stents fabrication. The use of 3D printing for stent manufacturing purpose is newly emerge and not widely reported. Up to now, less research has been conducted on 3D printed PLA coronary artery stents. This work therefore, aims to study the relationship of the 3D printing processing parameter towards stents quality. Strut thickness become the key aspects in stents manufacturing. Processing parameter optimization was performed by using Response Surface Methodology (RSM). Nozzle temperature and printing speed were both effecting the strut thickness formations regardless of printing orientations.

In the paper are shown the experimental results obtained for aluminum alloy, after application of the heat treatments by quenching solution and artificial ageing. The purpose of quenching solution treatment is to decrease the hardness and improve the machining for industrial parts made from this material. By artificial ageing treatment, the Al-Mg structure is modified, the hardness increase to the values necessary for a long exploitation of the parts.

To ensure customer satisfaction, the products made by aviation, space and defense organizations need to be continuously improved from the point of view of safety, security, reliability and maintainability. The improvement goal is to be at the customers' requirements and legislations level, if not even to overcome it. The occurring problem with the final products is the challenge to ensure their quality in a shorter time. In this research the importance of implementing the APQP concept in the aeronautical industry is highlighted. To achieve this purpose, the methodologies needed to ensure that the product development processes of the aviation, space and defense industry are fully integrated processes ranging from concept and design to planning, manufacturing and production, aiming the product good use, a quality service and finally getting a positive customer feedback. The final goal of this concept implementing is the Production Part Approval Process (PPAP), which is actually the main result of APQP confirming that the manufacturing process has demonstrated the potential to achieve products that consistently fulfil absolutely all the expressed and not expressed customer requirements.