Hidden dangers and challenges of 3D printing of th

2022-09-22
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Hidden dangers and challenges of 3D printing of selective laser sintering plastics

Abstract: despite its long history of decades, selective laser sintering (SLS) still has untapped potential, forming high-quality production parts that are difficult to make using other 3D printing methods. One of the biggest challenges in producing 3D printing of high-quality plastic parts is to observe the strength of the Z-axis in terms of its mechanical properties

despite its long history of decades, selective laser sintering (SLS) still has untapped potential to form high-quality production parts that are difficult to make using other 3D printing methods. One of the biggest challenges in producing 3D printing of high-quality plastic parts is to observe the mechanical performance of the z-axis experimental machine by reducing the strength of the selection and purchase standards of the experimental machine in the early stage

although companies such as essentium and rize3d have tried to overcome these limitations, they have made new modifications in fused filament manufacturing (FFF), and carbon has proved improved mechanical properties in a method similar to stereolithography (SLA). These companies are unique in providing more mechanically isotropic components

in contrast, SLS as a printing technology inherently provides more mechanically isotropic components. In addition, the powder bed in SLS printing is the natural support structure of parts, which makes it difficult to print geometric and vertical "nested" parts with FFF or SLA

how structural polymers solve the limitations of SLS 3D printing

however, SLS is limited by materials due to a limited number of commercially available thermoplastic powders. In addition, the development of SLS equipment lags behind other technologies, and the use of closed material platform by many large SLS printer manufacturers further restricts the adoption of new materials

we recently talked with Carl Deckard, the inventor of SLS printing company, and the co-founder of Vikram Devarajan, a structural polymer company, about their views on the future opportunities of SLS and how they envision material development to solve the core challenges of SLS printing in the whole value chain

selective laser sintering system has a series of price points, but due to the limited temperature range of many systems, the choice of materials is limited. The notable exception is bold

table: PA = polyamide; TPE = thermoplastic polyethylene; Peek = peek; PEKK = polyether ketone ketone; TPU = thermoplastic polyurethane

one of the main limitations of SLS today is the lack of materials that can be produced in the form of powder required for this printing method, which is reflected in the various available materials shown in the above table. Commercial plastic powder is usually made by one of the following two methods: freeze grinding or solvent precipitation

each of these methods is incompatible with many desired thermoplastics, and both methods are expensive and produce powders with a wide particle size distribution

structural polymers aim to expand the range of thermoplastic powders printed by SLS through their new method of producing powders through chopping fibers. The production method of its textile processing equipment can produce powder from a wide range of thermoplastics and show better controlled particle size distribution

although nylon 12 is the most common SLS material today, Carl and Vikram said that structural polymers have shown the production of several polymers of high commercial interest, of which acceptable powders cannot be used in SLS at present

these materials include elastomers (especially thermoplastic polyurethane), several kinds of polypropylene and polyester. Although material diversity is a necessary condition to promote the application, from the perspective of process, the schedule of verifying new powders by low-temperature grinding or solvent precipitation is still very slow, and can be expanded to meet the demand without affecting the quality and consistency of powders

the commercialization of new materials depends on the cooperation between material suppliers and printer manufacturers to provide material properties that compete with their conventionally manufactured analogues

in addition to a limited number of printable plastic powders, there are several device limitations for current SLS printers. Due to the early use of nylon in SLS, printers installed on most dates can only reach the maximum sintering temperature of 200 ° C, so high-performance polymers cannot be sintered (EOS and Oxford performance materials are notable exceptions)

sls changes on the horizon

in addition, most systems use too simple temperature control systems, which hinders the accuracy and final printing speed. Carl predicts that similar to the surge in innovation and design of FFF printers, allowing a more comprehensive range of printer prices and capabilities, SLS printers will be overhauled in the design process in the next five years, thereby eliminating the restrictions on temperature, speed, and the cost of early models

this technological innovation will require the commitment to invest in SLS and the support of material suppliers and product manufacturers, and there are already significant signs of support at the equipment level. Through sinterit, the low-cost SLS 3D printer obtained the research and development of FFF desktop professional printer reflected by sintratec and formlabs and the announcement of EOS' high temperature dual laser system, which is an early step for more convenient and production oriented SLS system

open materials system

the ultimate limit on the use of new materials in SLS printing is the closed business model used by major SLS printer manufacturers. Companies like 3D systems require customers to use the company's materials on their SLS systems and provide only limited materials

looking ahead, Carl and Vikram predict that the development of new materials will lead to a stronger demand for open systems that can use a wider range of thermoplastics. Prodways and other companies have developed in this direction as shown in the above table. Whether the closed system market leaders follow the open material model has become a problem for the future revenue of printer sales, which exceeds the future revenue loss of material sales to third parties. In this regard, although HP also uses nylon powder printing, its material platform is open, allowing third-party materials to be added and then exported to all parts of the world for evaluation, which is doing well

in the above table, we can see the progress of overcoming the limitations of current SLS printing technology, showing the technical specifications of some leading SLS printers in the market. Specifically, bold words show how some companies are beginning to address challenges related to equipment costs, material diversification, and temperature limits

however, the widespread adoption of SLS printing will require the cooperation of material developers, printer manufacturers and component manufacturers, and simulate vertical integration, which will help promote the successful application of metal powder bed technology in aerospace and medical applications

how to improve SLS 3D printing

although Karl said that the improvement of SLS printer will be driven by material development, material development needs to be concerned by printer developers and final parts manufacturers

companies interested in material development and supply should explore novel thermoplastic powder production methods and expand the scope of SLS thermoplastic through partnerships with start-ups such as structured polymers or through internal development

printer developers have the opportunity to differentiate themselves by cheaper, faster and higher processing temperature devices. Most importantly, product designers and manufacturers should consider customized products printed by SLS, which need better isotropic characteristics than those currently provided by FFF or SLA, and should cooperate with material and printer developers to promote materials and processing capabilities to the required product specifications

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