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As an advanced manufacturing method, additive manufacturing (AM) technology provides new possibilities for efficient production and design of parts. However, with the continuous expansion of the application of AM materials, subtractive processing has become one of the necessary steps to improve the accuracy and performance of parts. In this paper, the processing process of AM materials is discussed in depth, and the surface integrity problem caused by it is discussed.

Firstly, we listed and analyzed the characterization parameters of metal surface integrity and its influence on the performance of parts and then introduced the application of integrated processing of metal adding and subtracting materials and the influence of different processing forms on the surface integrity of parts. The surface of the trial-cut material is detected and analyzed, and the surface of the integrated processing of adding and subtracting materials is compared with that of the pure processing of reducing materials, so that the corresponding conclusions are obtained.

In this process, we also found some surface integrity problems, such as knife marks, residual stress and thermal effects. These problems may have a potential negative impact on the performance of the final parts. In processing, we can try to use other integrated processing technologies of adding and subtracting materials, try to combine various integrated processing technologies of adding and subtracting materials, or consider exploring more efficient AM technology to improve processing efficiency. We can also consider adopting production process optimization measures to reduce the processing cost of adding and subtracting materials.

With the gradual improvement of the requirements for the surface quality of parts in the production process and the in-depth implementation of sustainable manufacturing, the demand for integrated processing of metal addition and subtraction materials is likely to continue to grow in the future. By deeply understanding and studying the problems of material reduction and surface integrity of AM materials, we can better meet the challenges in the manufacturing process and improve the quality and performance of parts. This research is very important for promoting the development of manufacturing technology and achieving success in practical application.

Hybrid manufacturing technologies combining individual processes can be recognized as one of the most cogent developments in recent times. As a result of integrating additive, subtractive and inspection processes within a single system, the relative benefits of each process can be exploited. This collaboration uses the strength of the individual processes, while decreasing the shortcomings and broadening the application areas. Notwithstanding its numerous advantages, the implementation of hybrid technology is typically affected by the limited process planning methods. The process planning methods proficient at effectively using manufacturing sources for hybridization are notably restrictive. Hence, this paper aims to propose a computer-aided process planning system for hybrid additive, subtractive and inspection processes. A dynamic process plan has been developed, wherein an online process control with intelligent and autonomous characteristics, as well as the feedback from the inspection, is utilized.

In this research, a computer-aided process planning system for hybrid additive, subtractive and inspection process has been proposed. A framework based on the integration of three phases has been designed and implemented. The first phase has been developed for the generation of alternative plans or different scenarios depending on machining parameters, the amount of material to be added and removed in additive and subtractive manufacturing, etc. The primary objective in this phase has been to conduct set-up planning, process selection, process sequencing, selection of machine parameters, etc. The second phase is aimed at the identification of the optimum scenario or plan.

To accomplish this goal, economic models for additive and subtractive manufacturing were used. The objective of the third phase was to generate a dynamic process plan depending on the inspection feedback. For this purpose, a multi-agent system has been used. The multi-agent system has been used to achieve intelligence and autonomy of different phases.

A case study has been developed to test and validate the proposed algorithm and establish the performance of the proposed system.

The major contribution of this work is the novel dynamic computer-aided process planning system for the hybrid process. This hybrid process is not limited by the shortcomings of the constituent processes in terms of tool accessibility and support volume. It has been established that the hybrid process together with an appropriate computer-aided process plan provides an effective solution to accurately fabricate a variety of complex parts.

The purpose of this study is, to compare laser-based additive manufacturing and subtractive methods. Laser-based manufacturing is a widely used, noncontact, advanced manufacturing technique, which can be applied to a very wide range of materials, with particular emphasis on metals. In this paper, the governing principles of both laser-based subtractive of metals (LB-SM) and laser-based powder bed fusion (LB-PBF) of metallic materials are discussed and evaluated in terms of performance and capabilities. Using the principles of both laser-based methods, some new potential hybrid additive manufacturing options are discussed.

Production characteristics, such as surface quality, dimensional accuracy, material range, mechanical properties and applications, are reviewed and discussed. The process parameters for both LB-PBF and LB-SM were identified, and different factors that caused defects in both processes are explored. Advantages, disadvantages and limitations are explained and analyzed to shed light on the process selection for both additive and subtractive processes.

The performance of subtractive and additive processes is highly related to the material properties, such as diffusivity, reflectivity, thermal conductivity as well as laser parameters. LB-PBF has more influential factors affecting the quality of produced parts and is a more complex process. Both LB-SM and LB-PBF are flexible manufacturing methods that can be applied to a wide range of materials; however, they both suffer from low energy efficiency and production rate. These may be useful when producing highly innovative parts detailed, hollow products, such as medical implants.

This paper reviews the literature for both LB-PBF and LB-SM; nevertheless, the main contributions of this paper are twofold. To the best of the authors’ knowledge, this paper is one of the first to discuss the effect of the production process (both additive and subtractive) on the quality of the produced components. Also, some options for the hybrid capability of both LB-PBF and LB-SM are suggested to produce complex components with the desired macro- and microscale features.

To remanufacture a disused part, a hybrid process needs to be taken in part production. Therefore, a reasonable machining route is necessary to be developed for the hybrid process. This paper aims to develop a novel process planning algorithm for additive and subtractive manufacturing (ASM) system to achieve this purpose.

First, a skeleton of the model is generated by using thinning algorithm. Then, the skeleton tree is constructed based on topological structure and shape feature. Further, a feature matching algorithm is developed for recognizing the different features between the initial model and the final model based on the skeleton tree. Finally, a reasonable hybrid machining route of the ASM system is generated in consideration of the machining method of each different sub-feature.

This paper proposes a hybrid process planning algorithm for the ASM system. Further, it generates new process planning insights on the hybrid process service provider market.

The proposed process planning algorithm enables engineers to obtain a proper hybrid machining route before product fabrication. And thereby, it extends the machining capability of the hybrid process to manufacture some parts accurately and efficiently.

This study addresses one gap in the hybrid process literature. It develops the first hybrid process planning strategy for remanufacturing of disused parts based on skeleton tree matching, which generates a more proper hybrid machining route than the currently available hybrid strategy studies. Also, this study provides technical support for the ASM system to repair damaged parts.

This study aims to discuss the state-of-the-art digital factory (DF) development combining digital twins (DTs), sensing devices, laser additive manufacturing (LAM) and subtractive manufacturing (SM) processes. The current shortcomings and outlook of the DF also have been highlighted. A DF is a state-of-the-art manufacturing facility that uses innovative technologies, including automation, artificial intelligence (AI), the Internet of Things, additive manufacturing (AM), SM, hybrid manufacturing (HM), sensors for real-time feedback and control, and a DT, to streamline and improve manufacturing operations.

This study presents a novel perspective on DF development using laser-based AM, SM, sensors and DTs. Recent developments in laser-based AM, SM, sensors and DTs have been compiled. This study has been developed using systematic reviews and meta-analyses (PRISMA) guidelines, discussing literature on the DTs for laser-based AM, particularly laser powder bed fusion and direct energy deposition, in-situ monitoring and control equipment, SM and HM. The principal goal of this study is to highlight the aspects of DF and its development using existing techniques.

A comprehensive literature review finds a substantial lack of complete techniques that incorporate cyber-physical systems, advanced data analytics, AI, standardized interoperability, human–machine cooperation and scalable adaptability. The suggested DF effectively fills this void by integrating cyber-physical system components, including DT, AM, SM and sensors into the manufacturing process. Using sophisticated data analytics and AI algorithms, the DF facilitates real-time data analysis, predictive maintenance, quality control and optimal resource allocation. In addition, the suggested DF ensures interoperability between diverse devices and systems by emphasizing standardized communication protocols and interfaces. The modular and adaptable architecture of the DF enables scalability and adaptation, allowing for rapid reaction to market conditions.

Based on the need of DF, this review presents a comprehensive approach to DF development using DTs, sensing devices, LAM and SM processes and provides current progress in this domain.

The purpose of this paper is to investigate the combination of selective laser melting (SLM) and 5-axis CNC milling to produce parts from titanium powder. The aim is to achieve a more resource-efficient manufacturing process by reducing material wastage and machining time, while adhering to quality requirements.

A benchmark titanium aerospace component is manufactured with two different approaches using subtractive and additive manufacturing technologies. The first component is produced from a solid billet using only 5-axis CNC milling. The second component is grown from powder using SLM to produce a net-shaped part of which the final shape and part accuracy are achieved through 5-axis CNC milling. The potential saving of material and machining time of the process combination is evaluated by comparing it to the conventional purely CNC approach. The form accuracy, surface finish, mechanical properties and tool wear for the two processes are also compared.

The results show that the process combination can be used to produce Ti components that adhere to aerospace standards. With the process combination, a material saving of 87 per cent was achieved along with a reduction of 21 per cent in machining time. Further improvements are possible using optimized SLM build and machining strategies.

This paper presents the results of a resource efficiency assessment on the combination of SLM and 5-axis CNC milling for the titanium alloy, Ti6Al4V. It is expected that this process combination can make a significant contribution towards reducing material wastage and machining time for aerospace applications.

This paper aims to present a new design for removable partial dentures (RPDs) for partially edentulous patients to improve the efficiency and quality of RPD manufacturing. Additive and subtractive manufacturing technologies and zirconium silicate micro-ceramic bonding in the aesthetic zone are used herein.

A case was presented. First, RPD digital definitive casts were acquired, and then digital frameworks with crown retainers and digital crowns were obtained by computer-aided design (CAD). The titanium alloy frameworks and resin crowns were fabricated by three-dimensional (3D) printing and computer-aided manufacturing (CAM) processes, respectively. The crowns adhered to the crown retainers. Ceramage bonding was used to reform the gingival anatomy in the aesthetic zone during the fabrication of the RPDs. The finished RPDs were assessed by a clinician and delivered to the patient.

The RPDs were conventionally assessed by a clinician, were deemed to be accurate and satisfied both the patient and clinician.

This novel method provides a way to fabricate RPDs with a combination of additive and subtractive manufacturing technologies. The design of the framework was different from that of a conventional framework because it contained the crown retainers, and the traditional base retainer no longer existed. Ceramage bonding was used to replicate the gingival anatomy in the aesthetic zone. The new RPDs provided accuracy and were less time-consuming to produce than those produced with the traditional method. The new method enables the digital manufacturing of nearly the entire RPDs.

The purpose of this paper is to analyze the aerodynamic improvements obtained in a wing section with a NACA 0018 airfoil manufactured using the fused deposition modeling (FDM) technique with regard to a smooth surface made by milling. The creation of micro-riblets on the surface of the airfoil, due to the deposition of the material layer by layer, improves the general aerodynamic performance of the parts, provided that the riblets are parallel to the flow line. The incidence of the thickness of the thread deposited in each layer – to be the variable on which the geometry of the riblets is based – was studied.

The wing section was designed using 3D software. Three different models were designed by rapid prototyping, using additive and subtractive manufacturing. Two of the profiles were manufactured using FDM varying the thickness of the layer to be able to compare the aerodynamic improvements. The third model was manufactured using a subtractive rapid prototyping machine generating a smooth surface profile. These three models were tested inside the wind tunnel to be able to quantify the aerodynamic efficiency according to the geometry and the riblets size.

The manufacture of an aerodynamic profile using FDM provides, in addition to the lightness and the ability to design parts with complex geometries, an improvement in the aerodynamic efficiency of 10 per cent compared with profiles with a smooth surface.

With the aerodynamic advantage gained through the use of FDM positions, the additive manufacturing serves as an excellent alternative for the manufacture of lightweight aerodynamic parts, with low structural loading and with low Reynolds number (∼5·105). This technological advantage would be applied to the UAV (unmanned aerial vehicle) industry.

The study carried out in this article demonstrates that the use of FDM as a manufacture process of end-used parts that are subject to movement generates an additional advantage that had not been considered. The additive manufacturing allows us to directly manufacture riblets by creating the necessary surface so as to reduce the aerodynamic drag.

The purpose of this paper is to review additive and/or subtractive manufacturing methods for metallic objects and their gradual evolution from prototyping tools to rapid manufacture of actual parts.

Various existing rapid manufacturing (RM) methods have been classified into six groups, namely, CNC machining laminated manufacturing, powder‐bed technologies, deposition technologies, hybrid technologies and rapid casting technologies and discussed in detail. The RM methods have been further classified, based on criteria such as material, raw material form, energy source, etc. The process capabilities springing from these classifications are captured in the form of a table, which acts as a database.

Due to the approximation in RM in exchange for total automation, a variety of multi‐faceted and hybrid approaches has to be adopted. This study helps in choosing the appropriate RM process among these myriad technologies.

This review facilitates identification of appropriate RM process for a given situation and sets the framework for design for RM.

Subtractive rapid prototyping (SRP) uses layer‐based removal from a plurality of orientations in order to create geometry in a highly automated manner. However, unlike additive means, the method can be inefficient due to redundant cutting operations on previously machined regions. The purpose of this paper is to present process planning methods for SRP, specifically dealing with stock material management in multiple setup operations.

Analysis of remaining stock material was performed by considering slices of respective stereolithography (STL) models. Further, an initial approximation was made of accessibility to enable iterative visibility analysis. The combination of these approaches led to efficient and fast algorithms. After analysis, the slices could be converted back to useful STL models through polyhedral reconstruction.

This method of approximation yields results similar to exact geometry. Using remaining stock data from this approach leads to a significant reduction in tool path length and processing time in SRP.

This paper presents novel methods of geometric representation and inaccessible volume calculation for four‐axis layer‐based machining and shows a successful implementation in an SRP system.