The Effect of Layer Orientation on the Mechanical Properties and Microstructure of a Polymer

Abstract

Rapid Prototyping (RP) is a method used everywhere from the entertainment industry to healthcare. Layer orientation is an important aspect of the final product. The objective of this research was to evaluate the effect of layer orientation on the mechanical strength and toughness of a polymer. The polymer used was a combination of two materials, ZP 130 and ZB 58, fused together in the Z Corporation Spectrum Z510 Rapid Prototyping Machine. ZP 130 is a powder composed of vinyl polymer (2-20%), sulfate salt (0-5%), and plaster that contains <1% crystalline silica (50-95%). ZB 58 is a liquid composed of glycerol (1-10%), preservative (sorbic acid salt) (0-2%), surfactant (<1%), pigment (<1%), and water (85-95%). After removal from the machine the samples were sealed with Z bond 101 which is Beta-methoxyethyl cyanoacrylate (60-100%). The layer orientations studied were the crack arrestor, crack divider, and short transverse with various combinations of the three, for a total of seven orientations. The mechanical strength was evaluated using tensile testing and three-point bend testing. The toughness was evaluated by Izod impact testing. Five samples for tensile testing and three-point bend testing as well as 15 samples for the Izod impact test for each of the seven orientations were made. The total number of samples was 175. The crack arrestor orientation was the strongest main orientation for the tensile and three-point bend test. Weibull analysis was done on the Izod impact testing due to high variation in the results for the crack arrestor and short transverse directions. It was found that the layer orientation and surface roughness played a significant role in the penetration of the Z bond 101 coating and in the overall strength of the samples.

Comparison of stress concentrator fabrication for 3D printed polymeric izod impact test specimens

“…A c c e p t e d M a n u s c r i p t (SLA), electron beam melting (EBM), laser engineered net shaping (LENS), selected laser melting (SLM), and selected laser sintering (SLS) [12][13][14][15][16][17][18][19][20][21][22][23][24][25] therefore, any standardized test utilized to measure mechanical performance of materials intended for 3D printing should display some sensitivity towards build direction.…”

“…A material testing technique used to A c c e p t e d M a n u s c r i p t evaluate the mechanical properties of materials is pendulum impact testing such as Izod testing which has been utilized in literature [19] and by industry (notably as a materials specification by Stratasys Ltd. and its subsidiaries such as Objet) as a metric for mechanical properties of materials used in AM. Izod impact testing of materials is beneficial to 3D printing as it has been shown to be sensitive to build orientation [15,17]. A critical aspect of the Izod impact test is the use of a stress concentrator, in this case a V-shaped notch.…”

The effects of PLA color on material properties of 3-D printed components

“…toys) at the expense of more sophisticated designs for higher value products like tools or scientific equipment [20][21][22]. Current studies have described what effect the orientation of layers may have on the properties by using commercial grade powder printers [23] and using commercial grade fused deposition modeling (FDM) printers has shown a strength dependency on different types of infill patterns and internal structures [24]. Using a similar 3-D printer as Rosas [24] there has been data showing the ability of printed parts to perform between 65% and 72% as well in comparison to injection molded parts of the same material [25].…”

Characterizing the effect of additives to ABS on the mechanical property anisotropy of specimens fabricated by material extrusion 3D printing

“…While the advantages of AM are well known, the disadvantages are not widely addressed. Mechanical property anisotropy is an undesirable trait observed in components fabricated from material extrusion 3D printing (ME3DP) -more traditionally referred to by the trademarked moniker, fused deposition modeling (FDM)-as well as nearly every other AM technology such as electron beam melting (EBM), selected laser melting (SLM), selected laser sintering (SLS), stereolithography (SLA), and laser engineered net shaping (LENS) [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. In most cases, the mechanical property anisotropy is observed through the analysis of ultimate tensile strength (UTS) or impact resistance for parts fabricated in various directions, where Z-direction-built parts typically display lower tensile strength and impact resistance [1-10, 13, 14] values with the exception of parts fabricated via EBM [12].…”