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Behaviour of infiltrating materials on Calcium Sulphate hemihydrate parts made by 3D printing
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Procedia Manufacturing 13 (2017) 848–855 Procedia Manufacturing 00 (2017) 000–000 www.elsevier.com/locate/procedia
Manufacturing Engineering Society International Conference 2017, MESIC 2017, 28-30 June Manufacturing Engineering Society Conference 2017, International Vigo (Pontevedra), Spain2017, MESIC 2017, 28-30 June 2017, Vigo (Pontevedra), Spain
Behaviour of infiltrating materials on Calcium Sulphate
Behaviour of infiltrating materials on Calcium Sulphate Manufacturing Engineering Society International Conference MESIC 2017, 28-30 June hemihydrate parts made bySpain 3D2017, printing 2017, Vigo (Pontevedra), hemihydrate parts made by 3D printing
Castro*, P. Rodríguez-González, J. Barreiro, A.I. Fernández-Abia CostingM.A. models optimization in Industry 4.0: Trade-off M.A. Castro*for , P. capacity Rodríguez-González, J. Barreiro, A.I. Fernández-Abia Department of Mechanical, Informatics and Aerospatiale Engineering. Universidad de León, León 24071, Spain between used capacity andEngineering. operational Department of Mechanical, Informatics and Aerospatiale Universidad deefficiency León, León 24071, Spain A. Santana , P. Afonso , A. Zanin , R. Wernke Abstract Abstract a University of Minho, 4800-058 Guimarães, Portugal A capillary infiltration study is presented.bUnochapecó, Three-dimensional 3DSC, printing 89809-000inkjet Chapecó, Brazil samples were used using calcium sulfate A capillary infiltration study ismaterial. presented. inkjet 3D printing samples such were asused calcium sulfate hemihydrate as the raw ceramic This Three-dimensional manufacturing process involves some limitations highusing porosity, poor surface hemihydrate as the raw ceramic This manufacturing involves some porosity, poor surface quality and low strength, amongmaterial. others. These problems canprocess be corrected with the limitations infiltrators such used as in high the post-processing stage. quality and low strength, others. These problems can beinfiltrating corrected with the infiltrators used in the improvement post-processing The purpose of this workamong is to evaluate the effect of different materials and to determine of stage. some The purpose of infiltration. this work isFor to evaluate the effect of different and to determine the improvement of some properties after this purpose, different physicalinfiltrating properties materials (weight, roughness, infiltrating material penetration) Abstract properties after infiltration. For this purpose, different physical properties (weight, roughness, infiltrating material penetration) were studied. were studied. © 2017 The Authors. Published by Elsevier B.V. Under the concept of "Industry 4.0", production processes will be pushed to be increasingly interconnected, © 2017 The Authors. Published by B.V. committee of the Manufacturing Engineering Society International Conference Peer-review under responsibility of Elsevier the scientific © 2017 The Authors. Published by Elsevier B.V. necessarily, much more efficient. In this context, capacity optimization information basedresponsibility on a real time basis and, Peer-review under of the scientific committee of the Manufacturing Engineering Society International Conference 2017. Peer-review under responsibility of the scientific committee of the Manufacturing Engineering Society International Conference 2017. goes 2017.beyond the traditional aim of capacity maximization, contributing also for organization’s profitability and value. Indeed, management continuous approaches suggest capacity optimization instead of Keywords:lean Infiltrating Materials;and Inkjet 3D printing;improvement Capillary Infiltration maximization. The study of capacity and Infiltration costing models is an important research topic that deserves Keywords: Infiltrating Materials; Inkjet 3Doptimization printing; Capillary a
a,*
b
b
contributions from both the practical and theoretical perspectives. This paper presents and discusses a mathematical model for capacity management based on different costing models (ABC and TDABC). A generic model has been 1. Introduction 1. Introduction developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization’s Three-dimensional inkjet printing (3D printing) is one ofefficiency the powder-based additive technologies value. The trade-off capacity maximization vs operational is highlighted andmanufacturing it is shown that capacity Three-dimensional printing (3Daprinting) is one oftothe powder-based manufacturing technologies invented in MIT 1.hide It inkjet involves applying layer of powder a surface and usingadditive an ink jet printer head to accurately optimization might operational inefficiency. invented MIT 1. Itainvolves applying a layer of powder to a surface using an ink this jet printer head to spray surface with binder join powder particles. To make ceramicand materials using technology, theaccurately common © 2017the Thein Authors. Published bytoElsevier B.V. spray theissurface a binder to join powder particles. To make ceramic involves materialsnot using thisthe technology, the common method to mixwith ceramic powder with a binder. However, this process only printing process itself, Peer-review under responsibility of the scientific committee of the Manufacturing Engineering Society International Conference method to mix ceramic powder withpre-part a binder.design However, this powder process involves notcharacterization, only the printingbinder-powder process itself, but alsoisrequires a number of steps: (.STL), and binder 2017. but also requires a number of steps: pre-part design (.STL), powderpost-processing and binder characterization, interaction, selection of parameters of the printing process, and finally, specification. binder-powder interaction, selection of parameters of the printing process, and finally, post-processing specification. Keywords: Cost Models; ABC; TDABC; Capacity Management; Idle Capacity; Operational Efficiency * Corresponding author. Tel.: +34-987293588. * Corresponding Tel.: +34-987293588. E-mail address:author. [email protected] E-mail address: [email protected]
1. Introduction
The cost of idle capacity is a fundamental information for companies and their management of extreme importance in modern©production systems. In general, it isB.V. defined as unused capacity or production potential and can be measured 2351-9789 2017 The Authors. Published by Elsevier 2351-9789 2017responsibility The Authors. Published by Elsevier B.V.hours Peer-review of the scientific committee of the Manufacturing Engineering International Conference in several©under ways: tons of production, available of manufacturing, etc.Society The management of the 2017. idle capacity Peer-review underTel.: responsibility the761; scientific committee the Manufacturing Engineering Society International Conference 2017. * Paulo Afonso. +351 253 of 510 fax: +351 253 604of741 E-mail address: [email protected]
2351-9789 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the Manufacturing Engineering Society International Conference 2017. 2351-9789 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the Manufacturing Engineering Society International Conference 2017. 10.1016/j.promfg.2017.09.190
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In these steps some advantages and disadvantages of the technology have been identified. As an advantage, you can create shapes that are difficult or impossible to create by traditional methods. However, the problems identified for many years in the manufacturing process and in the manufactured parts still persist today: high porosity, poor surface quality, low resistance, degradation problems, cracking, thermal deformations...)2. Consequently, parts printed in 3D often do not reach the strength and surface quality required for the functional parts. Most of these problems can be addressed through post-processing, with the most common being the infiltration 3. Those materials with relatively low viscosity and good properties can be used as infiltrators. In the literature, several works have been done focusing on infiltration processes and different infiltrating agents (waxes, varnishes, lacquers, cyanoacrylate, polyurethane and epoxy) 4. Melcher et al 5 used alumina as a ceramic material in 3D printing and vacuum infiltrated with metallic copper. Vogt et al 6 improved the ceramic properties by vacuum infiltration. The calcium sulfate hemihydrate, starting raw material in this work, presents some of these disadvantages as low resistance and rapid degradation 7. In this work, it is a matter of studying some aspect prior to printing, as well as trying to improve the properties of calcium sulphate in the post-process. In the process and 3D printing it is important the depositability of the powder depending on the size and shape of the particle, therefore, the first objective characterize the starting powder. Next, an attempt was made to improve some physical aspects of the printed final specimen. The effect of different physical properties as a function of the infiltrating agent used was studied. The infiltration process was selected for capillary infiltration. 2. Methodology or Experimental Procedure 2.1. Raw materials In this study, calcium sulphate hemihydrate (CaSO4 .1/2H2O) was used as raw material with a solution of 2pyrrolidone binder with a high water content (3DSystem). The infiltrating materials used were: Epsom salt (MgSO4.7H2O); 2-methoxy-2-ethyl-cyanoacrylate; Paraffin wax and epoxy resin (EX-401). The working conditions for each of the infiltrators were as specified below. The cyanoacrylate infiltration process was performed at room temperature. In the case of the wax, it was necessary to introduce it in an oven and to schedule at 200ºC in order to dissolve it, and immediately the infiltration was carried out to avoid its solidification. Magnesium sulfate was diluted in hot water to 60 ° C, Epsom / water salt quantities were taken from the manufacturer, Visijet PXL UserGuide. The preparation of the resin begins with the heating of the component A (resin ex401) at 60 ° C in order to decrease its density and then a more homogeneous mixture as possible with the component B (catalyst epofer e416) is prepared for subsequent infiltration. It is important to carry out the infiltration quickly by controlling the temperature, as the resin and the catalyst undergo an exothermic polymerization process, which is solubilized. 2.2. Specimen preparation A specimen of 10 x 3 x 30 mm is designed (Fig. 1a-b). The specimens were made in two orientations: horizontally (Fig 1a) and vertically (Fig. 1b) to the printing bed. The number of specimens manufactured was 26, since all the tests were performed in triplicate. We work with four infiltrators and print in two directions, then (4 infiltrators + 2 directions) x 3 tests, there are 24 specimens. Finally, we need two other specimens, one horizontal and one vertical, which would remain without infiltrating for reference. Once fabricated, each was given a code of numbers and letters in order to be able to identify them correctly throughout the later experiments. 2.3. Capillary infiltration The test consists of placing one side of the specimen in contact with the surface of the infiltrating liquid and remaining in contact for two minutes maintaining the infiltrating level (Fig. 1c). After this time, the ascending of the infiltrator collapses and proceed to raise the specimen and remove it from the support. Subsequently the specimen will be allowed to dry without removing the leftover infiltrate, as it has not been fully submerged will not have a large amount on the surface. To keep the infiltrating level a system was used in which applying vessels communicating with a small vessel filled with the infiltrating liquid kept the liquid level.
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Fig. 1. Outline of the work process.
2.4. Equipment used A 3DP machine Project 660Pro (3DSystems, USA) was used with resolution 600 x 540 dpi and a build area of 254 x 381 x 203 m, with thickness of layer to 0,1mm, and a build speed of 2,54 centimeters per hour. A Mettler AE 240 semi-microanalytical balance (sensitivity ± 0.01mg) was used for weighing the specimens before and after to infiltration. In order to know infiltrate height of each infiltrate a Leica microscope, model Z16 APO connected to a digital camera Leica EC3 of 3.1 Megapixels has been used. It is also equipped with a Leica LED light source model KL 1500 LED plus. The working procedure consisted of taking reference points on the infiltrated specimens, as shown in the Fig. 2a y 2b.
Fig. 2. Images obtained by optical microscopy of two specimens infiltrated with (a) wax; (b) epoxy.
Characterization of raw material was performed in a JEOL scanning electron microscope (SEM) (Model JSM6100), equipped with an energy-dispersive X-ray detecting system (ED-XRS) (LINK) for evaluation of the elemental composition of the particles, and operated under recommended conditions (20kV acceleration voltage, 5 nA probe current). The measurements were performed without coating the sample with a conductor. The powder sample was deposited on a carbon adhesive. This equipment allows selection of work areas on the sample from X30 increases to X300000 increases. This allows us to go from an overall view of the powder sample to a more detailed one of each of the dust particles. In our case the selection of zones was made from X100 to X60000 increases. In these observations we were collecting images of secondary electrons (SE) that give us information about the morphology (shape and size
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of the particles). Simultaneously, an EDS elemental analysis is performed by recording the X-ray spectra produced by scanning secondary electrons on a large surface of the powder sample and at point locations of the particles. The roughness was assessed before and after part infiltration using a rugosimeter Mitutoyo SPJ-500. The probe used was the 12AAC731 with tip radius of 2µm and tip angle of 60º. The parameters used for the study of roughness have been Rt and Ra. For all the pieces the roughness was measured in the same zone. The measurements were made as shown in Fig. 3, in the direction of formation of the layer on the horizontally printed specimens (Fig. 3a), and in the direction perpendicular to the layer on the specimens fabricated in the vertical direction (Fig. 3b).
Fig. 3. Images of the specimens fabricated (a) horizontally; (b) vertically to the bed.
3. Results and Discussion 3.1. Raw Material Characterization Fig. 4a shows an X-ray spectrum collected on the image appearing in Fig. 4b, corresponding to an area taken at X100 magnification. In this spectrum appear the peaks relative to O, S and Ca, which will be the elemental composition of the sample. In this image obtained at X100 increases, the presence of carbon can be attributed to carbon adhesive, in which is deposited the powder. In spectra collected in powder specific areas appeared peaks relative to other elements. These results indicate that the powder sample has impurities. The images (SE) were derived from the secondary electrons. These micrographs made at different magnifications are shown in Fig 4 (b-d). Images 4b and 4c show the presence of particles that can be classified into two groups. The first group of particles with irregular shapes with sizes between 12 and 100 μm (Fig. 4a, b and c). And a second group of particles (Fig. 4c and 4d), with elongated forms whose termination appears irregular, which confers some roughness to the particles.
Fig. 4. (a) EDS spectrum (x100); Micrographs of secondary electrons obtained at different magnifications on the powder (b)X100; (c)X600 (d)X1900 y (e)X2500.
The morphology of the particles presented, it seems to be a typical of the phases and . The irregular particles correspond to the phase , while the elongated ones correspond to the phase 8.Therefore, it could be suggested that our starting material presents a combination of phases. 3.2. Weight variation and penetration of the infiltrating material The infiltration process, as well as the effect of the printing direction on this, was determined by studying two
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Weight Variation (%)
parameters: weight variation and penetration of the infiltrate (height measurement, as indicated in the methodology section). Fig. 5 shows the variation in weight percent of the test specimens, as a function of each of the infiltrates used.
10 9 8 7 6 5 4 3 2 1 0
9,5 7,3
6,9 5,3 3,9 2,1
EPOXY
1,5
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WAX Horizontal
CYANOCRYLATE EPSOM SALT Vertical
Fig. 5. Weight variation (%) of the specimen depending on the infiltrate used and the orientation of the impression.
A weight increase can be clearly observed for all specimens. Epsom salt and cyanoacrylate were the infiltrators that produced a greater weight increase in the specimen, being the epoxy resin that less modified the weight of the specimen. As can be seen in the figure this trend is the same for both directions of manufacture, although the increase is greater for the horizontal specimens. This difference could be explained by its position in contact with the infiltrating liquid during the capillary infiltration process (Fig. 6). As shown in Fig. 6a the liquid ascends in favor of layer in the horizontal ones, therefore, the liquid will penetrate more easily due to the path is more accessible. This is because the liquid is in contact with the area of the specimen in which the bonding between layers occurs, as a consequence, there will be gaps between them, in addition to the porosity that the sample presents by the arrangement of the particles. However, in the vertical ones (Fig. 6b) the liquid rises against layer. Therefore, in this case the contact zone of the liquid with the specimen presents the spaces due to the porosity that the piece will present, due to the heterogeneity in the size of the particles, as well as, to the weak union enters the particles in the piece.
Fig. 6. Schematic of the infiltration process for both printing orientations (a) horizontally (b) vertically
The concordance between the weight variation and infiltration penetration, it is proven to compare Fig. 5 and 7. Fig. 7 shows the penetration heights of the infiltrates. As in the previous case can be seen a similarity in the behavior of the infiltrates and same tendency in both directions of impression. The Epsom salt, under the working conditions
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Height Infiltration (mm)
described, was the one that reached a higher height of infiltration, followed by cyanoacrylate, the wax and finally the epoxy resin. We used the same explanation with the Fig. 6. We can also explain this increase in both weight and height of penetration with reference to density. The highest weights and heights of infiltration were obtained when working with the less dense infiltrates (Epsom salt and cyanoacrylate).
18 16 14 12 10 8 6 4 2 0
16,1
5,9
EPOXY
5,3
6,5
8,2
15,0
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WAX Horizontal
CYANOCRYLATE EPSOM SALT Vertical
Fig. 7. Variation of the Penetration Height as a function of the infiltrates used for the two printing orientations.
3.3.Roughness Fig. 8 shows the variation of the roughness. It can be seen that only for the wax and especially in the vertical direction, there is an improvement in the surface roughness of the piece. This can be explained by the direction in which the roughness was measured (Fig. 3). In the direction of measurement of the roughness on the vertical specimens the probe moves "against layer", therefore, the roughness measure can be contribution of two aspects: granulometry of the powder and the separation between the layer and the layer of powder (Fig. 9A1). It could be said that the wax softens the surface by correcting the roughness due to granulometry and the spaces between layers by filling them (Fig. 9A12. However, the measurements in the horizontal specimens were made “in favor of layer”, so in this case the probe only encounters the roughness due to the granulometry (Fig. 9B1). Therefore, the improvement in the surface roughness is due only to the correction of the effect of the particles (Fig. 9B2). On the contrary, the Epsom Salt worsens the surface roughness, especially in the vertical specimen (Fig 6). This could be due to the fact that during the infiltration a particle disintegration was observed in the specimen when the capillary infiltration process was carried out, especially in the area of contact of the specimen with the infiltrating agent. In the case of cyanoacrylate and epoxy resin, the values of Ra obtained do not present significant changes with respect to the values of the non-infiltrated sample.
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22,5 18,7
Ra (µm)
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6,9
8,1
7,2
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WAX
EPSOM SALT
Horizontal
CYANOCRYLATE NON INFILTRATE
Vertical
Fig. 8. Variation of Ra as a function of the infiltrates used for the two printing orientations.
Fig. 9. (A) Measurement surface on test pieces printed horizontally in the direction of measurement of roughness (1) before infiltration; (2) after infiltration. (B) Measurement surface on test pieces printed vertically in the direction of measurement of roughness (1) before infiltration (2) after infiltration.
4. Conclusions The raw material is possibly a mixture of the phases ( and ) according to the morphology of the particles found. This has to be supported by other techniques; X-ray diffraction and Raman and infrared spectroscopy are currently being analyzed. The highest weights and heights of infiltration were obtained when working with the less dense infiltrates (Epsom salt and cyanoacrylate). The infiltration by capillarity is favored when working with horizontally manufactured platforms. Therefore, it can be suggested that the porosity of the material is not the only factor which affects. Wax infiltrate improved surface quality above all in the vertically specimens. References [1] M.J. Cima, J.S.H.E.M. Sachs, P.A. Williams. Patent US5340656 A, Massachusetts Institute of Technology, USA. (1989) [2] M. Vaezi, C.K. Chua. Int. J. Adv. Manuf. Technol. 53 (2011) 275-284. [3] S. Maleksaeedi , H. Eng, F.E. Wiria, T.M.H. Ha, Z. He. J. Mater. Process. Technol. 214 (2014) 1301–1306.
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[4] J.F. Bredt, T.C. Anderson, D.B. Russell, United States: U.S. Patent and Trademark Office, Z Corporation. 6, 610 (2003) 429. [5] R. Melcher, S. Martins, N. Travitzky, P. Greil, Mat. Letter. 60 (2006) 572–575. [6] U.F. Vogt, M. Gorbar, P. Dimopoulos-Eggenschwiler, A. Broenstrup, G. Wagner, P. Colombo, J. Eur. Ceram. Soc. 30 (2010) 3005–3011. [7] M. Murariu, L. Bonnaud, P. Yoann, G. Fontaine, S. Bourbigot, P. Dubois, Polym. Degrad. Stab. 95 (2010) 374-381. [8] N. Singh, B. Middendorf, Prog. in Crys. Grow. and Charac. of Mat. 53 (2007) 57-77.
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Procedia Manufacturing 00 (2017) 000–000 Available Availableonline onlineatatwww.sciencedirect.com www.sciencedirect.com Procedia Manufacturing 00 (2017) 000–000
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www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia
Procedia Manufacturing 13 (2017) 848–855 Procedia Manufacturing 00 (2017) 000–000 www.elsevier.com/locate/procedia
Manufacturing Engineering Society International Conference 2017, MESIC 2017, 28-30 June Manufacturing Engineering Society Conference 2017, International Vigo (Pontevedra), Spain2017, MESIC 2017, 28-30 June 2017, Vigo (Pontevedra), Spain
Behaviour of infiltrating materials on Calcium Sulphate
Behaviour of infiltrating materials on Calcium Sulphate Manufacturing Engineering Society International Conference MESIC 2017, 28-30 June hemihydrate parts made bySpain 3D2017, printing 2017, Vigo (Pontevedra), hemihydrate parts made by 3D printing
Castro*, P. Rodríguez-González, J. Barreiro, A.I. Fernández-Abia CostingM.A. models optimization in Industry 4.0: Trade-off M.A. Castro*for , P. capacity Rodríguez-González, J. Barreiro, A.I. Fernández-Abia Department of Mechanical, Informatics and Aerospatiale Engineering. Universidad de León, León 24071, Spain between used capacity andEngineering. operational Department of Mechanical, Informatics and Aerospatiale Universidad deefficiency León, León 24071, Spain A. Santana , P. Afonso , A. Zanin , R. Wernke Abstract Abstract a University of Minho, 4800-058 Guimarães, Portugal A capillary infiltration study is presented.bUnochapecó, Three-dimensional 3DSC, printing 89809-000inkjet Chapecó, Brazil samples were used using calcium sulfate A capillary infiltration study ismaterial. presented. inkjet 3D printing samples such were asused calcium sulfate hemihydrate as the raw ceramic This Three-dimensional manufacturing process involves some limitations highusing porosity, poor surface hemihydrate as the raw ceramic This manufacturing involves some porosity, poor surface quality and low strength, amongmaterial. others. These problems canprocess be corrected with the limitations infiltrators such used as in high the post-processing stage. quality and low strength, others. These problems can beinfiltrating corrected with the infiltrators used in the improvement post-processing The purpose of this workamong is to evaluate the effect of different materials and to determine of stage. some The purpose of infiltration. this work isFor to evaluate the effect of different and to determine the improvement of some properties after this purpose, different physicalinfiltrating properties materials (weight, roughness, infiltrating material penetration) Abstract properties after infiltration. For this purpose, different physical properties (weight, roughness, infiltrating material penetration) were studied. were studied. © 2017 The Authors. Published by Elsevier B.V. Under the concept of "Industry 4.0", production processes will be pushed to be increasingly interconnected, © 2017 The Authors. Published by B.V. committee of the Manufacturing Engineering Society International Conference Peer-review under responsibility of Elsevier the scientific © 2017 The Authors. Published by Elsevier B.V. necessarily, much more efficient. In this context, capacity optimization information basedresponsibility on a real time basis and, Peer-review under of the scientific committee of the Manufacturing Engineering Society International Conference 2017. Peer-review under responsibility of the scientific committee of the Manufacturing Engineering Society International Conference 2017. goes 2017.beyond the traditional aim of capacity maximization, contributing also for organization’s profitability and value. Indeed, management continuous approaches suggest capacity optimization instead of Keywords:lean Infiltrating Materials;and Inkjet 3D printing;improvement Capillary Infiltration maximization. The study of capacity and Infiltration costing models is an important research topic that deserves Keywords: Infiltrating Materials; Inkjet 3Doptimization printing; Capillary a
a,*
b
b
contributions from both the practical and theoretical perspectives. This paper presents and discusses a mathematical model for capacity management based on different costing models (ABC and TDABC). A generic model has been 1. Introduction 1. Introduction developed and it was used to analyze idle capacity and to design strategies towards the maximization of organization’s Three-dimensional inkjet printing (3D printing) is one ofefficiency the powder-based additive technologies value. The trade-off capacity maximization vs operational is highlighted andmanufacturing it is shown that capacity Three-dimensional printing (3Daprinting) is one oftothe powder-based manufacturing technologies invented in MIT 1.hide It inkjet involves applying layer of powder a surface and usingadditive an ink jet printer head to accurately optimization might operational inefficiency. invented MIT 1. Itainvolves applying a layer of powder to a surface using an ink this jet printer head to spray surface with binder join powder particles. To make ceramicand materials using technology, theaccurately common © 2017the Thein Authors. Published bytoElsevier B.V. spray theissurface a binder to join powder particles. To make ceramic involves materialsnot using thisthe technology, the common method to mixwith ceramic powder with a binder. However, this process only printing process itself, Peer-review under responsibility of the scientific committee of the Manufacturing Engineering Society International Conference method to mix ceramic powder withpre-part a binder.design However, this powder process involves notcharacterization, only the printingbinder-powder process itself, but alsoisrequires a number of steps: (.STL), and binder 2017. but also requires a number of steps: pre-part design (.STL), powderpost-processing and binder characterization, interaction, selection of parameters of the printing process, and finally, specification. binder-powder interaction, selection of parameters of the printing process, and finally, post-processing specification. Keywords: Cost Models; ABC; TDABC; Capacity Management; Idle Capacity; Operational Efficiency * Corresponding author. Tel.: +34-987293588. * Corresponding Tel.: +34-987293588. E-mail address:author. [email protected] E-mail address: [email protected]
1. Introduction
The cost of idle capacity is a fundamental information for companies and their management of extreme importance in modern©production systems. In general, it isB.V. defined as unused capacity or production potential and can be measured 2351-9789 2017 The Authors. Published by Elsevier 2351-9789 2017responsibility The Authors. Published by Elsevier B.V.hours Peer-review of the scientific committee of the Manufacturing Engineering International Conference in several©under ways: tons of production, available of manufacturing, etc.Society The management of the 2017. idle capacity Peer-review underTel.: responsibility the761; scientific committee the Manufacturing Engineering Society International Conference 2017. * Paulo Afonso. +351 253 of 510 fax: +351 253 604of741 E-mail address: [email protected]
2351-9789 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the Manufacturing Engineering Society International Conference 2017. 2351-9789 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the scientific committee of the Manufacturing Engineering Society International Conference 2017. 10.1016/j.promfg.2017.09.190
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In these steps some advantages and disadvantages of the technology have been identified. As an advantage, you can create shapes that are difficult or impossible to create by traditional methods. However, the problems identified for many years in the manufacturing process and in the manufactured parts still persist today: high porosity, poor surface quality, low resistance, degradation problems, cracking, thermal deformations...)2. Consequently, parts printed in 3D often do not reach the strength and surface quality required for the functional parts. Most of these problems can be addressed through post-processing, with the most common being the infiltration 3. Those materials with relatively low viscosity and good properties can be used as infiltrators. In the literature, several works have been done focusing on infiltration processes and different infiltrating agents (waxes, varnishes, lacquers, cyanoacrylate, polyurethane and epoxy) 4. Melcher et al 5 used alumina as a ceramic material in 3D printing and vacuum infiltrated with metallic copper. Vogt et al 6 improved the ceramic properties by vacuum infiltration. The calcium sulfate hemihydrate, starting raw material in this work, presents some of these disadvantages as low resistance and rapid degradation 7. In this work, it is a matter of studying some aspect prior to printing, as well as trying to improve the properties of calcium sulphate in the post-process. In the process and 3D printing it is important the depositability of the powder depending on the size and shape of the particle, therefore, the first objective characterize the starting powder. Next, an attempt was made to improve some physical aspects of the printed final specimen. The effect of different physical properties as a function of the infiltrating agent used was studied. The infiltration process was selected for capillary infiltration. 2. Methodology or Experimental Procedure 2.1. Raw materials In this study, calcium sulphate hemihydrate (CaSO4 .1/2H2O) was used as raw material with a solution of 2pyrrolidone binder with a high water content (3DSystem). The infiltrating materials used were: Epsom salt (MgSO4.7H2O); 2-methoxy-2-ethyl-cyanoacrylate; Paraffin wax and epoxy resin (EX-401). The working conditions for each of the infiltrators were as specified below. The cyanoacrylate infiltration process was performed at room temperature. In the case of the wax, it was necessary to introduce it in an oven and to schedule at 200ºC in order to dissolve it, and immediately the infiltration was carried out to avoid its solidification. Magnesium sulfate was diluted in hot water to 60 ° C, Epsom / water salt quantities were taken from the manufacturer, Visijet PXL UserGuide. The preparation of the resin begins with the heating of the component A (resin ex401) at 60 ° C in order to decrease its density and then a more homogeneous mixture as possible with the component B (catalyst epofer e416) is prepared for subsequent infiltration. It is important to carry out the infiltration quickly by controlling the temperature, as the resin and the catalyst undergo an exothermic polymerization process, which is solubilized. 2.2. Specimen preparation A specimen of 10 x 3 x 30 mm is designed (Fig. 1a-b). The specimens were made in two orientations: horizontally (Fig 1a) and vertically (Fig. 1b) to the printing bed. The number of specimens manufactured was 26, since all the tests were performed in triplicate. We work with four infiltrators and print in two directions, then (4 infiltrators + 2 directions) x 3 tests, there are 24 specimens. Finally, we need two other specimens, one horizontal and one vertical, which would remain without infiltrating for reference. Once fabricated, each was given a code of numbers and letters in order to be able to identify them correctly throughout the later experiments. 2.3. Capillary infiltration The test consists of placing one side of the specimen in contact with the surface of the infiltrating liquid and remaining in contact for two minutes maintaining the infiltrating level (Fig. 1c). After this time, the ascending of the infiltrator collapses and proceed to raise the specimen and remove it from the support. Subsequently the specimen will be allowed to dry without removing the leftover infiltrate, as it has not been fully submerged will not have a large amount on the surface. To keep the infiltrating level a system was used in which applying vessels communicating with a small vessel filled with the infiltrating liquid kept the liquid level.
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Fig. 1. Outline of the work process.
2.4. Equipment used A 3DP machine Project 660Pro (3DSystems, USA) was used with resolution 600 x 540 dpi and a build area of 254 x 381 x 203 m, with thickness of layer to 0,1mm, and a build speed of 2,54 centimeters per hour. A Mettler AE 240 semi-microanalytical balance (sensitivity ± 0.01mg) was used for weighing the specimens before and after to infiltration. In order to know infiltrate height of each infiltrate a Leica microscope, model Z16 APO connected to a digital camera Leica EC3 of 3.1 Megapixels has been used. It is also equipped with a Leica LED light source model KL 1500 LED plus. The working procedure consisted of taking reference points on the infiltrated specimens, as shown in the Fig. 2a y 2b.
Fig. 2. Images obtained by optical microscopy of two specimens infiltrated with (a) wax; (b) epoxy.
Characterization of raw material was performed in a JEOL scanning electron microscope (SEM) (Model JSM6100), equipped with an energy-dispersive X-ray detecting system (ED-XRS) (LINK) for evaluation of the elemental composition of the particles, and operated under recommended conditions (20kV acceleration voltage, 5 nA probe current). The measurements were performed without coating the sample with a conductor. The powder sample was deposited on a carbon adhesive. This equipment allows selection of work areas on the sample from X30 increases to X300000 increases. This allows us to go from an overall view of the powder sample to a more detailed one of each of the dust particles. In our case the selection of zones was made from X100 to X60000 increases. In these observations we were collecting images of secondary electrons (SE) that give us information about the morphology (shape and size
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of the particles). Simultaneously, an EDS elemental analysis is performed by recording the X-ray spectra produced by scanning secondary electrons on a large surface of the powder sample and at point locations of the particles. The roughness was assessed before and after part infiltration using a rugosimeter Mitutoyo SPJ-500. The probe used was the 12AAC731 with tip radius of 2µm and tip angle of 60º. The parameters used for the study of roughness have been Rt and Ra. For all the pieces the roughness was measured in the same zone. The measurements were made as shown in Fig. 3, in the direction of formation of the layer on the horizontally printed specimens (Fig. 3a), and in the direction perpendicular to the layer on the specimens fabricated in the vertical direction (Fig. 3b).
Fig. 3. Images of the specimens fabricated (a) horizontally; (b) vertically to the bed.
3. Results and Discussion 3.1. Raw Material Characterization Fig. 4a shows an X-ray spectrum collected on the image appearing in Fig. 4b, corresponding to an area taken at X100 magnification. In this spectrum appear the peaks relative to O, S and Ca, which will be the elemental composition of the sample. In this image obtained at X100 increases, the presence of carbon can be attributed to carbon adhesive, in which is deposited the powder. In spectra collected in powder specific areas appeared peaks relative to other elements. These results indicate that the powder sample has impurities. The images (SE) were derived from the secondary electrons. These micrographs made at different magnifications are shown in Fig 4 (b-d). Images 4b and 4c show the presence of particles that can be classified into two groups. The first group of particles with irregular shapes with sizes between 12 and 100 μm (Fig. 4a, b and c). And a second group of particles (Fig. 4c and 4d), with elongated forms whose termination appears irregular, which confers some roughness to the particles.
Fig. 4. (a) EDS spectrum (x100); Micrographs of secondary electrons obtained at different magnifications on the powder (b)X100; (c)X600 (d)X1900 y (e)X2500.
The morphology of the particles presented, it seems to be a typical of the phases and . The irregular particles correspond to the phase , while the elongated ones correspond to the phase 8.Therefore, it could be suggested that our starting material presents a combination of phases. 3.2. Weight variation and penetration of the infiltrating material The infiltration process, as well as the effect of the printing direction on this, was determined by studying two
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Weight Variation (%)
parameters: weight variation and penetration of the infiltrate (height measurement, as indicated in the methodology section). Fig. 5 shows the variation in weight percent of the test specimens, as a function of each of the infiltrates used.
10 9 8 7 6 5 4 3 2 1 0
9,5 7,3
6,9 5,3 3,9 2,1
EPOXY
1,5
1,9
WAX Horizontal
CYANOCRYLATE EPSOM SALT Vertical
Fig. 5. Weight variation (%) of the specimen depending on the infiltrate used and the orientation of the impression.
A weight increase can be clearly observed for all specimens. Epsom salt and cyanoacrylate were the infiltrators that produced a greater weight increase in the specimen, being the epoxy resin that less modified the weight of the specimen. As can be seen in the figure this trend is the same for both directions of manufacture, although the increase is greater for the horizontal specimens. This difference could be explained by its position in contact with the infiltrating liquid during the capillary infiltration process (Fig. 6). As shown in Fig. 6a the liquid ascends in favor of layer in the horizontal ones, therefore, the liquid will penetrate more easily due to the path is more accessible. This is because the liquid is in contact with the area of the specimen in which the bonding between layers occurs, as a consequence, there will be gaps between them, in addition to the porosity that the sample presents by the arrangement of the particles. However, in the vertical ones (Fig. 6b) the liquid rises against layer. Therefore, in this case the contact zone of the liquid with the specimen presents the spaces due to the porosity that the piece will present, due to the heterogeneity in the size of the particles, as well as, to the weak union enters the particles in the piece.
Fig. 6. Schematic of the infiltration process for both printing orientations (a) horizontally (b) vertically
The concordance between the weight variation and infiltration penetration, it is proven to compare Fig. 5 and 7. Fig. 7 shows the penetration heights of the infiltrates. As in the previous case can be seen a similarity in the behavior of the infiltrates and same tendency in both directions of impression. The Epsom salt, under the working conditions
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Height Infiltration (mm)
described, was the one that reached a higher height of infiltration, followed by cyanoacrylate, the wax and finally the epoxy resin. We used the same explanation with the Fig. 6. We can also explain this increase in both weight and height of penetration with reference to density. The highest weights and heights of infiltration were obtained when working with the less dense infiltrates (Epsom salt and cyanoacrylate).
18 16 14 12 10 8 6 4 2 0
16,1
5,9
EPOXY
5,3
6,5
8,2
15,0
7,1
4,9
WAX Horizontal
CYANOCRYLATE EPSOM SALT Vertical
Fig. 7. Variation of the Penetration Height as a function of the infiltrates used for the two printing orientations.
3.3.Roughness Fig. 8 shows the variation of the roughness. It can be seen that only for the wax and especially in the vertical direction, there is an improvement in the surface roughness of the piece. This can be explained by the direction in which the roughness was measured (Fig. 3). In the direction of measurement of the roughness on the vertical specimens the probe moves "against layer", therefore, the roughness measure can be contribution of two aspects: granulometry of the powder and the separation between the layer and the layer of powder (Fig. 9A1). It could be said that the wax softens the surface by correcting the roughness due to granulometry and the spaces between layers by filling them (Fig. 9A12. However, the measurements in the horizontal specimens were made “in favor of layer”, so in this case the probe only encounters the roughness due to the granulometry (Fig. 9B1). Therefore, the improvement in the surface roughness is due only to the correction of the effect of the particles (Fig. 9B2). On the contrary, the Epsom Salt worsens the surface roughness, especially in the vertical specimen (Fig 6). This could be due to the fact that during the infiltration a particle disintegration was observed in the specimen when the capillary infiltration process was carried out, especially in the area of contact of the specimen with the infiltrating agent. In the case of cyanoacrylate and epoxy resin, the values of Ra obtained do not present significant changes with respect to the values of the non-infiltrated sample.
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25
22,5 18,7
Ra (µm)
20 15
7
14,6
10
16,1
13,5 5,7
6,9
8,1
7,2
6,9
5 0
EPOXY
WAX
EPSOM SALT
Horizontal
CYANOCRYLATE NON INFILTRATE
Vertical
Fig. 8. Variation of Ra as a function of the infiltrates used for the two printing orientations.
Fig. 9. (A) Measurement surface on test pieces printed horizontally in the direction of measurement of roughness (1) before infiltration; (2) after infiltration. (B) Measurement surface on test pieces printed vertically in the direction of measurement of roughness (1) before infiltration (2) after infiltration.
4. Conclusions The raw material is possibly a mixture of the phases ( and ) according to the morphology of the particles found. This has to be supported by other techniques; X-ray diffraction and Raman and infrared spectroscopy are currently being analyzed. The highest weights and heights of infiltration were obtained when working with the less dense infiltrates (Epsom salt and cyanoacrylate). The infiltration by capillarity is favored when working with horizontally manufactured platforms. Therefore, it can be suggested that the porosity of the material is not the only factor which affects. Wax infiltrate improved surface quality above all in the vertically specimens. References [1] M.J. Cima, J.S.H.E.M. Sachs, P.A. Williams. Patent US5340656 A, Massachusetts Institute of Technology, USA. (1989) [2] M. Vaezi, C.K. Chua. Int. J. Adv. Manuf. Technol. 53 (2011) 275-284. [3] S. Maleksaeedi , H. Eng, F.E. Wiria, T.M.H. Ha, Z. He. J. Mater. Process. Technol. 214 (2014) 1301–1306.
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[4] J.F. Bredt, T.C. Anderson, D.B. Russell, United States: U.S. Patent and Trademark Office, Z Corporation. 6, 610 (2003) 429. [5] R. Melcher, S. Martins, N. Travitzky, P. Greil, Mat. Letter. 60 (2006) 572–575. [6] U.F. Vogt, M. Gorbar, P. Dimopoulos-Eggenschwiler, A. Broenstrup, G. Wagner, P. Colombo, J. Eur. Ceram. Soc. 30 (2010) 3005–3011. [7] M. Murariu, L. Bonnaud, P. Yoann, G. Fontaine, S. Bourbigot, P. Dubois, Polym. Degrad. Stab. 95 (2010) 374-381. [8] N. Singh, B. Middendorf, Prog. in Crys. Grow. and Charac. of Mat. 53 (2007) 57-77.
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