Direct Metal Laser Sintering Method Research Articles

3D-printed titanium scaffolds loaded with gelatin hydrogel containing strontium-doped silver nanoparticles promote osteoblast differentiation and antibacterial activity for bone tissue engineering.

Bone tissue engineering offers a promising alternative to stimulate the regeneration of damaged tissue, overcoming the limitations of conventional autografts and allografts. Recently, titanium alloy (Ti) implants have garnered significant attention for treating critical-sized bone defects, especially with the advancement of 3D printing technology. Although Ti alloys have impressive versatility, their lack of cellular adhesion, osteogenic and antibacterial properties are significant factors that contribute to their failure. Hence, to overcome these obstacles, this study aimed to incorporate osteoinductive and antibacterial cue-loaded hydrogels into 3D-printed Ti (3D-Ti) scaffolds. 3D-Ti scaffolds were synthesized using the direct metal laser sintering method and loaded with a gelatin (Gel) hydrogel containing strontium-doped silver nanoparticles (Sr-Ag NPs). Compared with Ag NPs, Sr-doped Ag NPs increased the expression of Runx2 mRNA, which is a key bone transcription factor. We subjected the bioactive 3D-hybrid scaffolds (3D-Ti/Gel/Sr-Ag NPs) to physicochemical and material characterization, followed by cytocompatibility and osteogenic evaluation. The microporous and macroporous topographies of the scaffolds with Sr-Ag NPs showed increased Runx2 expression and matrix mineralization, with potent antibacterial properties. Therefore, the 3D-Ti scaffolds incorporated with Sr-Ag NP-loaded Gel hydrogels favored osteoblast differentiation and antibacterial activity, indicating their potential for orthopedic applications.

Experimental Study on the Effect of Process Parameters on the Build Time and Part Accuracy of Direct Metal Laser Sintering Components

3D printing is an emerging technology that creates parts straight from CAD models. Direct Metal Laser Sintering (DMLS) is a 3D printing method that is becoming increasingly popular in the aerospace, medical, and orthopedics sectors. These are usually focused on precise, long-lasting, and lightweight parts. DMLS is an Additive Manufacturing (AM) technique that employs a laser to sinter a selected area of a metallic powder layer by layer to produce the required metal components. The heating power of the laser was discovered to have a strong effect on phase formation. The major issue with this process is that high residual and large deformations are introduced to the components during manufacturing. This causes a change in the fatigue strength of a part and can even lead to cracks. The quality of the DMLS parts is affected by various process parameters. In this study, the design of experiments is used to investigate the consequences of process parameters used in the DMLS process to make metal parts. Process parameters such as laser power and scanning speed must be identified because they have the largest influence on the part's characteristics. (Build time, part accuracy). The change in the controlling parameters, or process parameters, in the DMLS method, has been found to affect material properties, according to a literature review. Thus, in the proposed work, three process parameters laser speed, scanning speed, and hatching distance are taken into account at two distinct levels. L4 orthogonal arrays are used in the studies. Experimental research is done on the manufacturing process, build time and component accuracy. Finally, the impact of each parameter on the quality aspects is discussed based on the experimental findings.

The impact of print orientation on the fracture resistance and failure patterns of additively manufactured cobalt-chromium post and cores.

The aim of this study was to evaluate the impact of the print orientation of direct metal laser sintering (DMLS) posts and cores on the fracture resistance and failure patterns of endodontically treated mandibular premolar teeth. Sixty intact human mandibular premolars were endodontically treated. The teeth were then randomly divided into four groups (n = 15). Cobalt-chromium (Co-Cr) metal posts were fabricated by traditional casting (Group C), and DMLS method in 0-, 45-, and 90-degree print orientations (Group DMLS 0, Group DMLS 45, and Group DMLS 90). The posts and cores were cemented with composite resin cement and subjected to compression test at a crosshead speed of 1mm/min. Data was analyzed by using one-way analysis of variance ANOVA and multiple comparison post hoc Tukey tests (α = 0.05). Specimens were viewed under a stereo microscope with x20 magnification to evaluate the fracture types. No significant differences were found among the groups tested in terms of fracture resistance (p>0.05). Group C and Group DMLS 0 group exhibited similar fracture patterns. It is possible to produce post and core restorations with the DMLS technique and use them clinically. Print orientation did not influence the fracture resistance. However, fracture patterns were different. Group C outperformed all DMLS groups in terms of fracture patterns.

Influence of Ion Nitriding on Microstructure and Properties of Haynes 282 Nickel Superalloy Specimens Produced Using DMLS Technique.

The paper investigates the influence of the ion-nitriding process on the microstructure, corrosion resistance, and tensile strength at elevated temperatures of Haynes 282 nickel superalloy specimens produced by the Direct Metal Laser Sintering (DMLS) technique. The study was performed for two conditions, i.e., as-built by DMLS method and as-built by DMLS method + covered by a layer containing CrN + Cr2N phases. An analysis of the surface morphology revealed that the ion-nitriding process significantly affects the physical and chemical phenomena occurring on the specimen's surface. The XRD measurement of the specimens showed that preparing them with the DMLS method as well as following a nitriding process produced residual tensile stresses. Based on the measurement of the nanohardness distribution through the layer approximatively of 7 μm in width and the superalloys substrate, the results of the nanohardness showed the maximum values of 27 GPa and 13.5 GPa for the nitrided layer and the substrate, respectively. The surface protection from the nitrided layer proved a positive effect on the corrosion resistance of the DMLS specimens in the solution of 0.1 M Na2SO4 + 0.1 M NaCl at room temperature. The results of the tensile tests at 750 °C showed that the ion-nitriding process did not significantly affect the elevated-temperature tensile strength of the superalloy specimens produced with the DMLS technique.

How can excess residual cement be reduced in implant-supported restorations?: An in vitro study.

The aim of this study was to investigate the effect of different cements and cementation techniques used in implant-supported restorations and the application of various vent modifications and extraoral replica techniques on the amount of overflowing cement in cemented systems. In this study, three different abutment designs were used as fully closed, occlusal vented, and occlusal + proximal vented. An extraoral replica was produced by milling the CAD/CAM ceramic block. The number of groups with and without replicas was determined as six (n = 10). For the cementation procedures, three different cements were tested: dual-cure resin, eugenol-free zinc oxide, and polycarboxylate cements. Cobalt-chromium superstructures to be cemented to the implant analog-abutment complex were produced by direct metal laser sintering method. Twenty-four hours after the cementation process, residual cement were measered with Micro-CT. In comparisons between groups, ANOVA test was used for normally distributed variables and Kruskall-Wallis H test was used for non-normally distributed variables at a significance level of p < 0.05. The difference in residual cement volumes between the groups in terms of both cementation techniques (whether or not to use an extraoral replica and different vent desings) and cement types was found to be statistically significant (p < 0.05). There was significantly less residual cement in all groups that used extraoral replicas than those that did not. As for the cement types, the most residual cement occurred in the resin cement. The use of extraoral replicas and vent designs on the abutment significantly reduces the amount of residual cement. Regardless of the cementation technique, the type of cement used affects the amount of excess cement. To reduce residual cement, both the type of cement and the cementation technique used must be considered.

Effect of Hardening Temperature on Maraging Steel Samples Prepared by Direct Metal Laser Sintering Process

This paper deals with the application of the direct metal laser sintering (DMLS) process, which already has a dominant position in the area of additive manufacturing (AM). This DMLS technology is used in many branches of industry and medicine, especially in piece production, small series, and prototypes. The portfolio of used metal powder materials includes aluminum alloys, austenitic steels, maraging steels, special alloys of nickel and titanium. The properties of these products are very often improved by further heat treatment after printing, such as a hardening process, by which microstructure and hardness can be increased. Heat treatment processes of metal AM components are already described, but experiments focused on optimization of these processes are still missing. In the article, the maraging steel samples printed by the DMLS method are subjected to testing after hardening processes, which differ by reducing the maintaining time at a defined temperature, recommended by the manufacturer. The result of the evaluation will be the reaching of similar results, which are set by the powder manufacturer, however, with shorter time of samples treatment. Therefore, the elevated temperature is selected, with the purpose of monitoring the shortest possible time of a temperature impact. The experimental temperature was set 590 °C with different durations at this temperature, for 1, 2, 3, 4, 5 and 6 h. The cooling process runs controlled in the furnace or in the still air. The maintaining time proved to be the most ideal already at 1 h exposure and cooled in the still air, where a higher hardness value of around 50 HRC was reached. During the resulting microstructure evaluations, fine carbids and martensitic lamellae were observed. More uniform and finer lamellar microstructure occurred at 5 and 6 h temperature intervals.

Effect of Plasma Nitriding on Structure and Properties of Titanium Grade 2 Produced by Direct Metal Laser Sintering

AbstractThis article presents the effect of an Indirect Plasma Nitriding process on the microstructure and properties of Titanium Grade- 2 samples manufactured by Direct Metal Laser Sintering Method (DMLS). It was determined, based on morphological analysis that the physical and chemical phenomena occurring at the surface during nitriding has a decisive effect on surface roughening. Phase and stress analysis shown the nitrided layer produced in a pure nitrogen at 760 °C and containing TiN + TiN0.30 + Ti2N is under compressive stress and its characteristic of a high hardness and Young Modulus as compare to Grade 2 titanium samples produced only by DMLS technique (without nitriding). Static tensile stress carried out at room temperature show that the nitrided samples containing TiN + TiN0.30 + Ti2N have much lower yield (YS0.2) and tensile strength (UTS) compared to the not nitrided samples. Tests carried out in Ringer’s solution, using impedance and potentiodynamic methods at temperatures elevated to 36.6 ± 0.3 °C to simulate human-’s’ body temperature, show that nitriding increased corrosion resistance of the alloy.

The Impact of Plastic Deformation on the Microstructure and Tensile Strength of Haynes 282 Nickel Superalloy Produced by DMLS and Casting.

The article presents the results of research on the influence of plastic deformation on the microstructure and tensile strength of Haynes 282 nickel superalloy produced by direct metal laser sintering (DMLS) and a conventional technique (casting). Samples were tested for dimensional accuracy using a 3D scanner. Then, the samples were subjected to plastic deformation by rolling. The microstructures of the DMLS and the as-cast samples were analysed using a scanning electron microscope. The strength properties of the samples were determined in a static tensile test. Microhardness measurements of the samples were also performed. Based on the analysis of the dimensional accuracy, it was found that the surface quality of the components produced by DMLS is dependent on the input parameters of the 3D printing process. Using the DMLS method, it is possible to produce Haynes 282 with a fine-crystalline microstructure containing dendrites. The fine-crystalline dendritic microstructure and low porosity showed very good tensile strength compared to the as-cast material. It was also found that the increase in the degree of plastic deformation of the as-cast Haynes 282 and the samples produced by the DMLS technique resulted in an increase in the strength of the tested samples, with reduced ductility.

Investigation of mechanical and surface properties of additively manufactured AlSi10Mg part produced through direct metal laser sintering

Additive manufacturing (AM) is a cutting-edge method of producing geometrically complex three-dimensional components. Conventional manufacturing has few limitations to build intricate shapes. AM solves the complexity issue by building components with layer-by-layer deposition method. Besides that, AM has less material wastage and superior structural characteristics. Direct Metal Laser Sintering (DMLS) is a powder bed fusion method to fabricate complex geometries. AlSi10Mg is used in a variety of structural applications due to its high strength, hardness, and dynamic characteristics. In this study, the mechanical and surface properties of additively manufactured AlSi10Mg parts by DMLS method have been investigated and compared with the properties of conventional casting samples. Mechanical and surface characteristics such as density, tensile strength, hardness, and surface roughness have been examined. The energy density of 56 J/mm3 is applied to melt powder particles by keeping laser power 125 W, layer thickness 30 µm, hatch space 135 µm and scanning speed 550 mm/s. The average density of 96.70 % is obtained for AM manufactured AlSi10Mg samples. The tensile strength of 377 MPa with 5% elongation and Vickers hardness of 102.4 HV has been achieved for AM-built samples. The surface roughness of 6 Ra has been attained for as-built AM AlSi10Mg part. Mechanical properties were observed better in additively manufactured components as compared to conventionally casted aluminium alloy. This research study would help in the selection of process parameters to obtain better mechanical properties for additively manufactured compared to cast AlSi10Mg alloy.

Development of aerostatic porous bearings manufactured using metal 3D printing technology

Aerostatic porous bearings have been applied widely in precision devices to achieve higher accuracy of motion. Conventional aerostatic porous bearings are made of porous graphite, porous ceramics or sintered metal porous material, having a thickness of several millimetres and a surface-restricted layer. However, during mass production of porous bearings, the time required for the production of the porous materials and the surface restriction treatment leads to an increase in the manufacturing time and cost of the porous bearings. Accordingly, to overcome this problem, an aerostatic porous bearing with a layer thickness of several hundred µm and a support member, manufactured using metal 3D printing technology, is proposed. In this study, the optimum conditions for manufacturing the proposed aerostatic porous bearings with a direct metal laser sintering method 3D printer were investigated, and characteristics of the prototype of the proposed bearings were investigated experimentally.

Influence of 3D Printing Topology by DMLS Method on Crack Propagation.

The presented text deals with research into the influence of the printing layers’ orientation on crack propagation in an AlSi10Mg material specimen, produced by additive technology, using the Direct Metal Laser Sintering (DMLS) method. It is a method based on sintering and melting layers of powder material using a laser beam. The material specimen is presented as a Compact Tension test specimen and is printed in four different defined orientations (topology) of the printing layers—0°, 45°, 90°, and twice 90°. The normalized specimen is loaded cyclically, where the crack length is measured and recorded, and at the same time, the crack growth rate is determined. The evaluation of the experiment shows an apparent influence of the topology, which is essential especially for possible use in the design and technical preparation of the production of real machine parts in industrial practice. Simultaneously with the measurement results, other influencing factors are listed, especially product postprocessing and the measurement method used. The hypothesis of crack propagation using Computer Aided Engineering/Finite Element Method (CAE/FEM) simulation is also stated here based on the achieved results.

Convection in Scaled Turbine Internal Cooling Passages With Additive Manufacturing Roughness

Abstract Additive manufacturing processes, such as direct metal laser sintering (DMLS), enable the creation of novel turbine cooling internal passages and systems. However, the DMLS method produces a significant and unique surface roughness. Previous work in scaled passages analyzed pressure losses and friction factors associated with the rough surfaces, as well as investigated the velocity profiles and turbulent flow characteristics within the passage. In this study, the heat transfer characteristics of scaled additively manufactured surfaces were measured using infrared (IR) thermography. Roughness panels were CNC machined from plates of aluminum 6061 to create near isothermal roughness elements when heated. Fluid resistance differences between the aluminum roughness panels and roughness panels constructed from ABS plastic using the same roughness patterns from McClain et al. (2020, “Flow in a Simulated Turbine Blade Cooling Channel With Spatially Varying Roughness Caused by Additive Manufacturing Orientation,” ASME Turbo Expo 2020, Turbomachinery Technical Conference and Exposition, Virtual Conference, Sept. 21–25, GT2020-16069) were investigated. Finally, the overall thermal performance enhancements and friction losses were assessed through the calculation of surface averaged “global thermal performance” ratios. The global thermal performance characterizations indicate results in-line with those found for traditional commercial roughness and slightly below traditional internal passage convection enhancement methods such as swirl chambers, dimples, and ribs. The passages investigated in this study do not include compressibility effects or the long-wavelength artifacts and channel geometric deviations observed by Wildgoose et al. (2020, “Impact of Additive Manufacturing on Internal Cooling Channels with Varying Diameters and Build Directions,” ASME Turbo Expo 2020, Turbomachinery Technical Conference and Exposition, Virtual Conference, Sept. 21–25, GT2020-15049). However, the results of this study indicate that, based on the roughness augmentation alone, artificial convective cooling enhancers such as turbulators or dimples may still be required for additively manufactured turbine component cooling.

THE EFFECT OF MACHINING PROCESSES ON THE PHYSICAL AND SURFACE MORPHOLOGY OF Ti6Al4V SPECIMENS PRODUCED THROUGH POWDER BED FUSION ADDITIVE MANUFACTURING

The most critical component of Industry 4.0, the new face of the machinery-manufacturing industry sector, is metal additive manufacturing. Laser-based additive manufacturing techniques are dominant for metal additive manufacturing today. In this study, the metal alloy studied is Ti-6Al-4V, one of the essential Ti alloys used in more than 50% of all commercial Ti applications. Ti-6Al-4V parts produced by additive manufacturing are used in the biomedical, aerospace-defence industry, and industrial areas due to their high strength, fatigue behaviour, fracture strength, good corrosion resistance, and biocompatibility. In the study, samples of Ti6Al4V alloy were produced with different manufacturing parameters by the direct metal laser sintering (DMLS) method, which is one of the powder bed fusion methods. Then, the surface qualities of the samples were processed by milling and wire EDM. The effects of machining operations on the surface roughness of the samples were investigated and compared with the surface roughness obtained from the samples produced by the DMLS method. After the optical microscope images of the samples were taken, the physical and surface morphology were examined. Although the mechanical properties of the parts manufactured by DMLS methods were higher, the samples with machining presented higher machinability with lower forces, lower surface roughness. the This is explained that mechanical properties of samples of Ti6Al4V alloy in additive manufacturing are highly dependent on the rapid cooling of the material. Results show that samples of Ti6Al4V manufactured by additive manufacturing has been possible using with machining.

Copper nickel alloys made using direct metal laser sintering method for assessing corrosion resistance properties

Direct Metal Laser Sintering (DMLS) is an additive manufacturing technique, a novel processes in vogue recent times, as it has the supreme advantage of producing near net shape component having low porosity levels and superior mechanical properties. The main thrust of the work focuses on the development of coppper-nickel (Cu-Ni) alloys using 3D printing for studying the rate of corrosion in sea water and in acidic conditions, as such work has not been reported in the literature. In this context, the Cu-Ni alloy with varying thickness 20, 40 and 60 μm was prepared by the DMLS technique at different scan speeds. The composition of the alloys was confirmed using X-ray diffraction technique (XRD), and energy dispersive spectroscopy (EDAX). The analysis of microstructure was done using light and scanning electron microscopy (SEM). Hardness was measured for all the prepared alloys using Vickers hardness tester and energy densities was analysed.Further, to study the durability, the samples were tested for corrosion resistance by average weight loss method. The weight loss trials were carried out in seawater condition i.e., 3% sodium chloride (NaCl) and in acidic medium (1 M HCl), at room temperature. The results show that the Cu-Ni alloy exhibits extreme resistance to corrosion in 3% NaCl but is found to be less resistant in 1 M HCl solution. The average weight loss of the sample is 0.72% in seawater whereas, in 1 M HCl, is 9.73%. Also, it reveals that the least thickness samples prepared at the lowest scan speed by DMLS technique are better resistance towards corrosion to that of the higher thickness samples made at higher scan speed. The corrosion data are well supported by microstructures, the surface of the samples was subjected to light and SEM before and after corrosion. This high resistance in NaCl makes copper-nickel alloys made by DMLS process ideal to use in marine locations.

Evaluation of Bacterial Adhesion to the ZrO2 Atomic Layer Deposited on the Surface of Cobalt-Chromium Dental Alloy Produced by DMLS Method.

The main purpose of the research was to analyze the influence of surface modification of the cobalt-based alloy used in dental prosthetics by applying zirconium oxide (ZrO2) layers using the ALD (Atomic Layer Deposition) method. The samples were made using the DMLS (Direct Metal Laser Sintering) technique, and their surfaces were prepared in accordance with the principles of removable partial dentures (RPDs). A 50 nm-thick zirconium oxide coating was applied to the prepared substrates. This paper deals with the issues of prosthetic stomatopathy, which is a complex of pathological changes occurring in approx. 40% of the Polish population using removable dentures. Often, these changes, occurring on the mucosa, are related to improper performance, allergic reactions or the multiplication of bacteria on the surface of partial dentures. An innovative method of surface modification was proposed, together with the analysis of its influence on the physicochemical properties of the alloy and the adhesion of bacteria to the surface.

A titanium implant for Chiari malformation Type 1 surgery.

Background: Concepts of Chiari malformation Type 1 (CM1) surgery in the present time significantly different. The most common complications are pseudomeningocele (12%) and postoperative CSF leak (5%). The development of pseudomeningocele may be associated with inappropriate restoration of bone and muscles relations.Methods: The pilot study involved 11 patients aged 24–64 years with a diagnosis of CM1 who had indications for surgical treatment. Special titanium implant enabling fixation of the occipital and cervical muscles at the projections of their normal attachments was developed, it was placed to occipital bone on the final stages of surgical intervention. Surgical technique promoted tightened wound closure neutralizing formation of “dead space” at the place of occipital craniectomy and between muscle layers. The implant was produced by direct metal laser sintering method for each patient individually.Results: There were no complications during the hospitalization and follow-up period. Postoperative MRI demonstrated adequate formation of the cisterna magna and the absence of pseudomeningocele. During follow-up period there were no signs of pseudomeningocele, CSF leak, surgical scar complications, implant-associated infections, and other complications.Conclusion: In the study group, no pseudomeningocele cases as long as any other complications associated with surgery had been revealed. The efficacy of the proposed surgical technique using the developed implant should be evaluated in clinical trials with larger patient samples. To simplify preoperative planning and manufacturing of the implant for each patient individually, a set of implants with different specified sizes was developed.

Effect of print orientation using DMLS method on strength of materials

The paper reported the results of a study concerned with the principle of operation of the 3D printing technology using the method of selective sintering of metallic powders, and taking into account their advantages and drawbacks. The principle of the operation of 3D printing technology applying the DMLS (Direct Metal Laser Sintering) method is presented. On the basis of the performed tests, the anisotropy of the printed materials is demonstrated. The reasons responsible for this phenomenon are identified. The paper presents the results of the strength tests which indicate that the crack during the test occur in the building direction of the layers during printing. The results were compiled for two different types of specimens and two different testing machines.

Strain Analysis of Ti6Al4V Titanium Alloy Samples Using Digital Image Correlation.

Digital image correlation (DIC) is a non-contact optical method that allows measuring displacements on a plane used to determine the strains caused by external loads of a structural element (mechanical or thermal). Currently, digital image correlation is a widely used experimental technique to assess the mechanical behavior of materials, in particular cracking characteristics and destruction methods of various structural elements. In this paper, the DIC method is applied to determine local strains of titanium alloy Ti6Al4V specimen. The samples used in the tests were made with two different technologies: (a) from a drawn bar by machining process; and (b) by the additive manufacturing method Direct Metal Laser Sintering (DMLS). The aim of the paper is to present the mechanical properties test results of the Ti6Al4V titanium alloy produced by the DMLS additive manufacturing under static loads using the digital image correlation method. As a result of the tests carried out on the drawn bar specimens, it was concluded that the change in the measurement base affects the difference in the Young’s E modulus value in the range from 89.2 to 103.8 GPa. However, for samples formed using the DMLS method, the change in the Young’s modulus value was from 112.9 to 115.3 GPa for the same measurement base.

Optimum Process Parameters for Direct Metal Laser Sintering of Ti6Al Powder Blend

Titanium aluminides have become the preferred titanium-based alloys for high temperature applications due to their resistance to oxidation at elevated temperatures. However, the inherent limitations of the conventional methods of manufacturing have adverse effects on the mechanical properties of the alloy and limit its applications. The current study focused on determining the optimum process parameters that could be used to produce a Ti6Al alloy with required microstructural properties and complex geometrical configurations using the direct metal laser sintering method. Single tracks were produced at laser powers of 150 W and 350 W over a wide range of scanning speeds. Continuous tracks were achieved only at a laser power of 150 W at corresponding scanning speeds of 1.0 m/s to 1.4 m/s. A cross sectional analysis was conducted on the single tracks and 1.2 m/s emerged as the optimum scanning speed. 3D objects were manufactured at optimum process parameters of 150 W, 1.2 m/s and a hatch distance of 80 µm. The microstructure of the 3D objects was homogenous which attests that the direct metal laser sintering method could be used to produce Ti6Al parts with the desired mechanical properties and geometrical complexity.

ON THE DESIGN AND FABRICATION OF CHAINED-FUNCTION WAVEGUIDE FILTERS WITH REDUCED FABRICATION SENSITIVITY USING CNC AND DMLS

In this paper, we present the design and fabrication of a novel class of emerging waveguide filters based on chained-functions at the millimeter-wave band. The derivation of chained-functions by chaining of prescribed generalized Chebyshev seed functions based on the partition theory is presented in details, and the implementation to waveguide technology is proposed and evaluated. The waveguide filter is fabricated through two different technologies, namely the Computer Numerical Control (CNC) milling technology and the Direct Metal Laser Sintering (DMLS) based additive manufacturing technology. The chained-function filters, which lie in between the Butterworth and Chebyshev filters, inherit the salient properties of both Butterworth and Chebyshev filters. Therefore, the chained-function waveguide filter exhibits filtering responses that have a superior rejection property and a lower loss with reduced sensitivity to fabrication tolerance than the standard Chebyshev waveguide filter. The efficiency of the proposed waveguide filter is confirmed both theoretically and empirically, using the CNC and DMLS processes. The issues of a higher manufacturing tolerance and apparent surface roughness associated with the DMLS method are found to be electrically insignificant when the chained-function concept is adopted in waveguide filter design. In general, the measured results of all the realized waveguide filters agree well to those of the simulation models. These results positively demonstrate that the chainedfunction concept has robust properties for rapid, high-performance, low-cost, and sustainable filter design and implementation, particularly for higher millimeter-wave frequency bands and for narrowband applications. © 2020.