The basis for guaranteeing the quality of printed goods is the state of raw materials; so, their purity and performance are critical. Medical titanium alloys, pure tantalum, and nickel titanium alloys are among the principal raw materials utilised in modern additive manufacturing equipment-metal powders used for 3D printing. Since the raw materials for metal 3D printing are mostly spherical powders, it is essential to define these materials in terms of roundness, sphericity, flowability, tap density, loose density, and other factors, and to confirm whether their physical and chemical properties meet the criteria for medical device production. For example, in the case of medical titanium alloy powder, it is crucial to ensure that its chemical composition meets relevant standards and that the concentration of impurities remains at very low levels to maintain the mechanical properties and biocompatibility of the implant.
Manufacturers of recycled old powders for 3D printing must offer explanations and proof for the combined powders. Based on these circumstances, check the effect of the printing environment on the powder; show process stability and clinical acceptability; and ascertain the possible effect of powder recycling on the printing process and results. Otherwise, we do not recommend using recycled powder products. Recycling powder can be affected by factors such as pollution and oxidation, which may lead to uncertain quality in printed goods.
3D printing medical device manufacture depends on printing equipment as a necessary hardware. The stability of equipment operation and printing technique defines if the batch variations of goods fall within a reasonable range. For instance, unstable printing equipment used in the manufacture of orthopaedic implants could cause deviations in the size accuracy, mechanical characteristics, etc. of the implants, therefore influencing the surgical result and patient recovery.
Strict verification processes in the printing process of equipment help to guarantee the stability and viability of the process. Regarding equipment alteration, one also needs to confirm the rationality and efficiency. Following the installation and equipment debugging, a thorough performance test, including testing of laser power stability, scanning accuracy, powder uniformity, etc., should be carried out to guarantee that the equipment can precisely print qualified medical devices according to the preset process parameters.
The first printed product has to go through required post-processing, including powder residue removal, surface roughness treatment, and thermal stress elimination. Important guarantees for maintaining the reasonable mechanical characteristics and biocompatibility of the product are these post-processing procedures. Strict control of the printing parameters-that is, printing temperature, printing speed, laser power, etc.-is essential throughout processing. Printing too rapidly can influence the density and strength of the product; excessive printing temperature may produce unequal melting of components, leading to flaws such as pores and cracks.
Right now, the China National Medical Products Administration is working on a standard called "Metal Powder Cleaning and Cleaning Effect Verification Method for Medical Additive Manufacturing Powder Bed Melting Forming Process," which mainly focusses on the technical details of "Common Cleaning Processes for Residual Metal Powder." Following this control, manufacturers can show cleaning compliance and apply cleaning policies. For instance, it is crucial to make sure remaining metal powder is completely eliminated after cleaning to prevent patient irritability or infection hazards. Simultaneously, techniques like microscopic inspection and chemical analysis should be used to find the leftover powder content on the surface of the product to verify the cleaning effect.
Apart from fulfilling performance criteria following manufacture, 3D printed medical devices must also address the possible effects on human health upon interaction with the human body. To check for metal ions that may come from 3D printed titanium alloy implants, the China National Medical Products Administration has created and approved a method called the "Evaluation Method for Metal Ion Precipitation of 3D Printed Titanium Alloy Implants for Additive Manufacturing Medical Products." The standard outlines the required metal ions (Ti, Al, V, and impurity element Fe) and the sample form for evaluation. Additionally, tests are required to evaluate the chemical composition, microstructure, pore shape, dynamic and static mechanical properties, friction characteristics, surface roughness, microcracks, internal inspection, and metal corrosion resistance of the product. Tensile and bending tests verify the mechanical qualities of the product so that it can resist physiological loads from the human body. The microstructure of the product can be observed under a microscope to guarantee that it satisfies design criteria.
The evaluation technique and criteria for quality uniformity of 3D printed metal implant products are specified in the "Evaluation Method and Criteria for Quality Uniformity of 3D Printed Metal Implants". Companies can assess the relevant products depending on the internal quality control system and features of 3D-printed metal implant products. Quality uniformity covers chemical composition, internal quality, microstructure, size, surface quality, surface roughness, porous structure, and mechanical characteristics. For items from the same batch, for instance, it is imperative to guarantee their chemical composition is consistent and prevent unstable product performance resulting from composition variations.
Risk analyses for 3D printed medical devices should include looking at how raw materials perform, what is needed for printing, changes made during printing, how post-processing affects material properties, and whether the materials are safe for use in the body. For instance, the printability of various materials-metals, ceramics, polymers, etc.-varies, and multiple modifications could happen during the printing process, including volatilising, thermal denaturing, etc. These developments might influence the product's safety and quality.
We can achieve 3D printing repeatability and validation-including validation using other printers-by applying the same conditions at multiple printing sites, varying printing durations and batches, etc. By using repeated validation, we guarantee the stability and uniformity of product quality. To see whether the performance indicators of the same product are constant, for instance, print it using the same printer several times and places.
Ensuring the safety of medical equipment depends critically on sterilising and cleaning. Control the residual particle count within a reasonable range to ascertain the suitable cleaning technique and confirm its efficiency. Regarding sterilisation, one must decide on the technique applied and whether it affects the instruments-especially those with porous structures. For example, for orthopaedic implants with porous structures, it is vital to verify that the sterilising process can totally kill germs without causing damage to the structure and performance of the implant.
The conscientious physician should retain training records, have matching surgical-level qualifications, acquire pertinent knowledge on customised 3D-printed medical items, and have associated qualifications. Medical institutions should have matching surgical-level qualifications as well as the capacity to track adverse occurrences of tailored medical gadgets and assess the usage of such tools. In orthopaedic surgery, for instance, the responsible doctor should be familiar with the features and use techniques of 3D-printed orthopaedic implants, be able to properly evaluate the patient's condition, choose suitable implants, and follow the patient's postoperative recovery.
Design and development personnel should have strong competency in creating customised 3D-printed medical devices, particularly in controlling software compatibility and ensuring accurate and complete data conversions during the design and development process. Simultaneously one should become proficient in pertinent medical knowledge, have the capacity to interact with medical professionals, be familiar with the performance criteria of tailored medical devices created and developed, and go through training in relevant knowledge. Designers must be able, for instance, to closely interact with doctors and precisely create medical devices that fit the anatomical structure of the patient depending on CT scan data.
Production companies have to build a quality control system, satisfy the production licence or filing criteria for tailored 3D printed medical equipment, and run normally. Having the necessary skills to operate 3D printing equipment, equipment operators should pass the evaluation and receive training. Customisable 3D-printed medical device performance criteria and standards should be familiar to production management staff. Validation of 3D printing equipment should ensure that its technical indicators and operations satisfy the needs of use. To guarantee controllable product quality, for instance, manufacturing companies have to rigorously follow the quality management system; equipment operators should be competent in the operation techniques of the equipment to prevent product quality problems generated by inappropriate operation.
https://www.china-3dprinting.com/metal-3d-printing/3d-printing-lightweight-hydraulic-block.html