Additive manufacturing (AM) alias 3D printing translates computer-aided design (CAD) virtual 3D models into physical objects. By digital slicing of CAD, 3D scan, or tomography data, AM builds objects layer by layer without the need for molds or machining. AM enables decentralized fabrication of customized objects on demand by exploiting digital information storage and retrieval via the Internet. The ongoing transition from rapid prototyping to rapid manufacturing prompts new challenges for mechanical engineers and materials scientists alike. Because polymers are by far the most utilized class of materials for AM, this Review focuses on polymer processing and the development of polymers and advanced polymer systems specifically for AM. AM techniques covered include vat photopolymerization (stereolithography), powder bed fusion (SLS), material and binder jetting (inkjet and aerosol 3D printing), sheet lamination (LOM), extrusion (FDM, 3D dispensing, 3D fiber deposition, and 3D plotting), and 3D bioprinting....

Polymers for 3D Printing and Customized Additive Manufacturing

Additive manufacturing (AM) technology has been researched and developed for more than 20 years. Rather than removing materials, AM processes make three-dimensional parts directly from CAD models by adding materials layer by layer, offering the beneficial ability to build parts with geometric and material complexities that could not be produced by subtractive manufacturing processes. Through intensive research over the past two decades, significant progress has been made in the development and commercialization of new and innovative AM processes, as well as numerous practical applications in aerospace, automotive, biomedical, energy and other fields. This paper reviews the main processes, materials and applications of the current AM technology and presents future research needs for this technology.

Additive manufacturing: technology, applications and research needs

Progress in Additive Manufacturing and Rapid Prototyping

Along with extensive research on the three-dimensional (3D) printing of polymers and metals, 3D printing of ceramics is now the latest trend to come under the spotlight. The ability to fabricate ceramic components of arbitrarily complex shapes has been extremely challenging without 3D printing. This review focuses on the latest advances in the 3D printing of ceramics and presents the historical origins and evolution of each related technique. The main technical aspects, including feedstock properties, process control, post-treatments and energy source–material interactions, are also discussed. The technical challenges and advice about how to address these are presented. Comparisons are made between the techniques to facilitate the selection of the best ones in practical use. In addition, representative applications of the 3D printing of various types of ceramics are surveyed. Future directions are pointed out on the advancement on materials and forming mechanism for the fabrication of high-performance ceramic components.

3D printing of ceramics: A review

Materials for additive manufacturing

A novel rapid prototyping technology incorporating a curved layer building style was developed. The new process, based on laminated object manufacturing (LOM), was designed for efficient fabrication of curved layer structures made from ceramics and fiber reinforced composites. A new LOM machine was created, referred to as curved layer LOM. This new machine uses ceramic tapes and fiber prepregs as feedstocks and fabricates curved structures on a curved‐layer by curved‐layer basis. The output of the process is a three‐dimensional “green” ceramic that is capable of being processed to a seamless, fully dense ceramic using traditional techniques. A detailed description is made of the necessary software and hardware for this new process. Also reviewed is the development of ceramic preforms and accompanying process technology for net shape ceramic fabrication. Monolithic ceramic (SiC) and ceramic matrix composite (SiC/SiC) articles were fabricated using both the flat layer and curved layer LOM processes. For making curved layer objects, the curved process afforded the advantages of eliminated stair step effect, increased build speed, reduced waste, reduced need for decubing, and maintenance of continuous fibers in the direction of curvature.

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Development of a curved layer LOM process for monolithic ceramics and ceramic matrix composites

Recent developments in rapid prototyping provide evidence of the maturing of some areas of application. New applications continue to surface and new systems/processes are being introduced on a regular basis. The Fifth International Conference on Rapid Prototyping (Dayton, Ohio, 1994) provided an opportunity to bring together leaders in the commercial development and application of RP technology and to hear their perspectives on the current capabilities and future directions. A “Manufacturers round table” provided the forum for the audience to submit questions. Relates participants’ responses.

Rapid prototyping: current technology and future potential

A novel rapidprototyping (RP) technology incorporating a curved layer building style has been developed. The new process,based on Laminated Object Manufacturing (LOM), is suited for efficient fabrication of curved layer structures made from ceramics and fibrous composites. Anew LOM machine was developedithatuses ceramic tapes and fiberprepregs as a feedstock and outputs at11fee dimensional green form. The green ceramic is then processed to a seamless, fully dense ceramic structure using traditional ceramic techniques. This report summarizes the new LOM process. and necessary hardware. Also reviewed is the development of ceramic preforms and accompanying process technology for net shape fabrication of ceramic matrix composites (CMCs). Compared to making curved objeds with the standard flat .layer LOMprocess, the curved process affords the advantages of eliminated stair-step effect, increased build speed, reduced waste,reduced need for decubing, and the ability to maintain continuous fibers in the direction of curvature.

Curved Layer LOM of Ceramics and Composites

Reducing Warpage In Stereolithography Through Novel Draw Styles

An innovative, rapid prototyping (RP) technology is being adapted for the automated manufacture of composite tools and molds. The technology is a direct extension of the Laminated Object Manufacturing (LaM) process. LaM is an established technique that is used to create solid prototypes by sequentially cutting and laminating layers of adhesive paper. With this process a full scale, geometrically complex prototype can be created directly from a CAD image in less than a day. This report provides a description ofhow LaM is being applied for the production of functional composite laminates, such as composite tools and molds. Several material systems have been examined, including monolithic ceramics (SiC), ceramic matrix composites (SiC/SiC), and polymer matrix composites (glass/epoxy). Realistic tools and molds are being created from these materials using the LaM process with little modification. However, post processing (ceramic densification, polymer post cure) is necessary to obtain articles with good mechanical properties. Technical solutions are being developed for maintaining geometrical accuracy during the post processing cycles. The mechanical properties and performance of the LaM-produced parts are reported herein. Overall, this technology holds great promise for lowering the cost of tooling due to the ability to create geometrically complex objects rapidly using a highly automated processing sequence.

Allan Lightman

Papers

Development of a curved layer LOM process for monolithic ceramics and ceramic matrix composites

Rapid prototyping: current technology and future potential

Curved Layer LOM of Ceramics and Composites

Reducing Warpage In Stereolithography Through Novel Draw Styles

Structural Composites Via Laminated Object Manufacturing (LOM)