Voxeljet, a German 3D printer manufacturer, has announced financial results for Q3 2018. According to the report, total revenues decreased from €7.12m in Q3 2017 to €7.39m for the current reporting period, a fall of 3.6%. It further shows a general decline in the Systems segment of voxeljet, whereas the Service segment has shown an […]
Investigating Lightweight 3D Printed Structures for Sand Casting
3D printing is often used to produce molds for casting. In the case of sand molds, binder jetting is typically used; however, its high costs, due to expensive materials, need to be lowered, according to the authors of a study entitled “Mechanical Analysis of Ceramic/Polymer Composite with Mesh-Type Lightweight Design Using Binder-Jet 3D Printing.” In the study, the researchers investigate the mechanical properties of sand molds with a lightweight structure for low material consumption and short process time.
Binder jetting is a faster method of making sand molds than conventional casting, but it’s still too expensive, according to the researchers. In the study, they work to find a methodology of the lightweight design in a smaller length scale for binder jetting 3D printing, such as a typical conformal lattice cell in metal.
“To investigate the mechanical properties of lightweight designs, we introduce a basic unit block sample of a ceramic/binder composite applied to a whole sand mold using a BJ 3D printer in this study,” they explain. “The selection of two different structures was just done in this research for the purpose of comparing a typical lightweight design for metal with our ideal structure. We also address geometrical effects, such as the size and shape of typical lightweight patterns provided by commercial DfAM software on the basis of mechanical property evolution.”
To study the basic design factors of a lightweight structure for a sand/polymer composite, the researchers introduced two types of lightweight structures: a box with square holes (Type-1) and a lattice with upper and bottom pads (Type-2). The specimens were 3D printed using a sand binder jetting 3D printer from voxeljet. A compression test was performed by placing the samples between circular steel plates. Each test was conducted twice for accuracy. Each sample was broken by initiation of cracks, and no creep was observed.
The researchers also conducted computational analysis in order to predict stress distribution and fracture under uniaxial-loading, and FEM simulations were carried out. Several major conclusions were reached from the study:
The strength of both designs significantly decreased with increasing volume ratio. The size of the inner hold in the Type-1 sample should be at least 2mm for taking out the inner sand powder cleanly. Although the Type-1 sample had higher strength, it was more difficult to take out sand particles from the samples than it was with Type-2. Therefore, future studies will focus on enhancing the low strength of the Type-2 sample.
With mesh-type lightweight structures, increasing pad thickness and decreasing mesh area results in increasing local stress concentration at the interface of the mesh and pads. Easy cracking is initiated at a comparatively weak boundary between mesh and pads in the case of thick pad thickness.
“Since a commercial software for topology optimization provides lightweight designs for rigid single component materials such metals or plastics, it is not suitable to apply the lightweight designs to a ceramic/polymer composite with different mechanical behaviors,” the researchers continue. “As a result, new types of light weight structures for sand casting molds are required to spread BJ 3D printing technology to the foundry industry.”
Finally, further work will suggest and evaluate the new lightweight and rigid design for additive manufacturing of a ceramic/polymer composite. It should reveal the correlation between structural and mechanical factors of the lightweight designs in detail.
Authors of the paper include Dong-Hyun Kim, Jinwoo Lee, Jinju Bae, Sungbum Park, Jihwan Choi, Jeong Hun Lee and Eoksoo Kim.
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voxeljet’s James Reeves announces automotive additive manufacturing production line
Industrial 3D printer manufacturer voxeljet is working on an additive manufacturing production line for the automotive industry. The so-termed “VJET X-IOB” system is reportedly “ten times faster” than the company’s currently available 3D printers, with full integrated pre and post processing capabilities. Speaking to James Reeves, Managing Director at voxeljet UK who broke the news, I […]
Voxeljet reports revenue growth for Q2 2018 led by strong 3D printing services segment
Industrial 3D printer manufacturer voxeljet AG (NYSE:VJET) has released its financial results for the second quarter and first half of FY2018. Headline revenue for the three months ended June 30, 2018 was reported at €5.3 million, an increase of 2.1% on the same period in 2017 which was €5.1 million. The rise in revenue from this period was led […]
Metal 3D Printing and Classic Foundry Techniques: Friends or Foes?
The first question that is often asked when a new technology is introduced is: what of the old way of doing things? Sometimes the answer is that it fades into oblivion — think: fortran and floppy disks — other times it falls out of use in mainstream society but becomes the domain of a small, especially devoted community, like calligraphy or pedal loom weaving. And in other cases, it simply shifts its focus and allows itself to flower as it removes extra ‘noise’ from the workflow. John Phillip Sousa wondered if the invention of the phonograph might cause human beings to lose their vocal chords as they would no longer have to sing any song they wished to hear, and an equally pessimistic (although slightly more realistic) group worried that the Kindle would eradicate books altogether.
What has happened is that humanity has access to more music than ever and book production may see a fall in the print of throwaway paperbacks, but there appears to be no reason to fear that beautiful books will be eliminated from publication. One new technology that is causing both concern and overinflated speculation is the introduction of metal 3D printing. The question is: what impact will this technology have on traditional foundries? Foundry work is not inherently antithetical to 3D printing as many have, in fact, been using 3D printing to create molds for years now and have found the technology to be quite helpful in their production.
Beyond the printing of 3D molds, metal 3D printing is demonstrating a capacity for directly creating metal objects that is improving with each passing project. Voxeljet, which recently produced a new design for aircraft doors using 3D metal printing, doesn’t think that this signals the end of the classic foundry, however. Instead, they see it as something akin to a separate track of printing. What made the doors they produced such a good candidate for 3D printing was the need for a precise internal geometry, something impossible to be produced in a foundry. So rather than stealing work from a foundry, they were doing work that otherwise would not have been performed at all. And there are other reasons not to see metal 3D printing as a threat to foundry work, as voxeljet explained in a statement:
“3D metal printing, such as direct metal laser sintering (DMLS), currently only competes with foundries in a relatively small segment. The build spaces of DMLS systems are ideally suited to smaller components. And 3D-printed components for aerospace require time-consuming certification, which metal casting has had for decades already. Direct 3D metal printing is also relatively expensive. This is not only due to the high cost of metal powder, but also the high cost of 3D printers and the comparatively slow building speeds.”
In addition to these factors, the products of 3D printing in metal require hand finishing which is labor intensive. All of these factors lead up to an average cost for 3D printed metal pieces that hovers around $160 per pound for aluminum, and $215 per pound for stainless steel, whereas pure cast steel has a price point of about $15 per pound. However, with the introduction of less expensive machinery, greater build bed sizes, and a more experienced workforce, the input prices for 3D printed metal are bound to come down. And so the question arises: will there be a change as the costs associated with metal 3D printing fall?
This uncertainty necessarily creates a degree of concern among those whose businesses and livelihoods depend upon a demand for foundry work. Rather than viewing the technology as an enemy to be shut out, perhaps the best solution is for foundries to get ahead of the game and embrace the tech, integrate it into their workflows and determine for themselves what makes sense to leave to a 3D printer and what can still only be produced at the hands of skilled foundry workers. As Ingo Edere, CEO at voxeljet, stated:
“3D sand and plastic printing are a perfect alternative for foundries, both in terms of cost, as well as the printable complexity. Foundries can manufacture equally complex components without having to change the process chain. Foundries do not have to purchase their own 3D printing systems as there are service providers worldwide supplying 3D sand or plastic printing.”
Clearly, a company such as voxeljet believes in the efficacy of this technology and its firm place as part of the landscape of future production. However, just because something can be 3D printed, doesn’t always mean that it should be, and discerning artisans and clients alike are the ones who will ultimately have to determine where that line lies.
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