Substrate Release Mechanisms for Gas Metal Arc Weld 3D Aluminum Metal Printing
Total Page：16
File Type：pdf, Size：1020Kb
Original Article Substrate Release Mechanisms for Gas Metal Arc Weld 3D Aluminum Metal Printing Amberlee S. Haselhuhn , 1 Eli J. Gooding , 1 Alexandra G. Glover , 1 Gerald C. Anzalone , 1 Bas Wijnen , 1 Paul G. Sanders , 1 and Joshua M. Pearce 1,2 Abstract Limited material options, prohibitively expensive equipment, and high production costs currently limit the ability of small and medium enterprises to use 3D printing to prototype and manufacture metallic goods. A low - cost open - source 3D metal printer that utilizes gas metal arc welding technology has been developed that could make metal printing accessible to the average consumer. Unfortunately, this technology would demand access to expensive cutting tools for part removal from the substrate. This article investigates several substrate treatments to provide a low - cost method to easily remove 3D - printed 1100 aluminum parts from a reusable substrate. Coatings of aluminum oxide and boron nitride on 1100 aluminum and A36 low - carbon steel substrates were tested. Lap shear tests were performed to assess the interlayer adhesion between the printed metal part and the print substrate. No warping of the substrate was observed during printing. It was determined that boron nitride - coated low - carbon steel provided the lowest adhesion strength. Printing aluminum on uncoated low - carbon steel also allowed easy removal of the aluminum part with the benefit of no additional coating steps or costs. Introduction 3D metal printing is commercially electron beam freeform fabrication,11 and available in several forms: laser - based microwelding 12,13 in a single - layer 3 D printing has the potential to additive manufacturing, weld - based multipass welding regime. Parts revolutionize the way goods are additive manufacturing, and shape produced by weld - based additive manufactured on a global scale, enabling deposition modeling. Laser - based manufacturing are inexpensive and mass customization while reducing both additive manufacturing methods include nonporous with good interlayer capital investment and production powder bed fusion (direct metal laser adhesion, but have a limited print costs. 1,2,3,4 The ability of small and sintering), 5 selective laser sintering, 6 resolution and poor surface finish. medium enterprises (SMEs) to make selective laser melting, 7 and directed Microwelding is the exception, exhibiting full use of this potential is currently energy deposition (laser cladding). 6 excellent dimensional control and finer restricted by material choice. Most These methods offer excellent surface finish resulting from the small - SMEs only have local access to polymeric dimensional control but have large diameter electrode and wire employed. fused filament fabrication (plastic production costs due to the use of lasers material extrusion). Third - party or metal powders. Shape deposition manufacturing prototyping services offer a broader processes feature both additive and range of print media, including Weld - based additive manufacturing subtractive manufacturing.14,15,16 A single ceramics and metals. Most commercial methods include gas metal arc welding layer of metal is melted, sintered, or 3D metal printers are out of reach of (GMAW), 8,9 gas tungsten arc welding, 10 welded in a rough net shape and then SMEs as they typically cost more than directed energy deposition and powder subsequently milled down to a precise $ 500,000. bed fusion (electron beam melting), 7 geometry before the next layer of metal is Departments of 1 Materials Science & Engineering and 2 Electrical & Computer Engineering, Michigan Technological University , Houghton, Michigan. 204 3D PRINTING MARY ANN LIEBERT, INC. • VOL. 1 NO. 4 • 2014 • DOI: 10.1089/3dp.2014.0015 Substrate Release Mechanism printed. These processes have excellent dimensional control but are expensive and time - consuming as both printing and computer numerical control (CNC) milling equipment are required to produce a part. The high cost and slow throughput of the current commercial metal 3D printers limit their application to expensive finished products such as custom hip replacements and maxillofacial repairs.17 There is thus an urgent need for a low - cost 3D printer capable of depositing metals directly for both rapid prototyping and rapid manufacturing for SMEs. Recent development of a low - cost open - source 3D metal printer exploiting GMAW technology offers the potential for the general public to 3D print metal parts.18 This printer, based on the RepRap concept19 (self - rep licating rap id prototyper), is capable of being partially manufactured either by itself or produced in an incremental fashion from components produced by a standard fused filament fabrication system. It utilizes a moving stage upon Figure 1. Labeled photograph of the three - axis stage with attached aluminum weld gun. which the substrate is placed and a fixed print head comprised of a workshop GMAW. Aluminum and steel parts have interface between the 3D - printed part metal arc welder and a three - axis stage as been printed with this printer using and substrate was quantified using a lap shown in Figure 1 . 16 The GMAW, a single - pass, multilayer welding and were shear measurement commonly employed Millermatic 140 with Spoolmate 100 removed from the substrate with a to assess the strength of adhesives.20 The weld gun, supplied the material used to vertical band saw. This method of part results are discussed and a generalized print and the energy required to melt the removal is suboptimal as it requires mechanism is proposed for enabling material. The three - axis stage was additional processing equipment, costs, substrate selection for aluminum microprocessor controlled, permitting and time. Thus, an alternative method is GMAW 3D printing. precise CNC of both the position and desired. speed of the platform upon which parts were printed. The part was built upon a This article investigates several substrate Materials and Methods sacrificial 6.35 - mm - thick mild steel or treatments to provide low - cost release aluminum plate. mechanisms to remove 3D - printed Description of a 3D Metal Printer aluminum metal parts from the print The stage was derived from an open - substrate, outlined in Table 1 . The The metal printer comprised two distinct source 3D printer design known as a substrate adhesion and strength of the components, a workshop - grade gas Rostock, 21 which is a RepRap derivative. Table 1. Substrate release mechanisms analyzed by this study Mechanism Print material Coating Coating thickness (µ m) Substrate 1 ER1100 aluminum None 0 1100 aluminum 3 ER1100 aluminum Aluminum oxide 18.8 1100 aluminum 3 ER1100 aluminum Boron nitride 5.9 1100 aluminum 2 ER1100 aluminum None 0 A36 low - carbon steel 3 ER1100 aluminum Aluminum oxide 18.8 A36 low - carbon steel 3 ER1100 aluminum Boron nitride 5.9 A36 low - carbon steel MARY ANN LIEBERT, INC. • VOL. 1 NO. 4 • 2014 • DOI: 10.1089/3dp.2014.0015 3D PRINTING 205 Haselhuhn et al. The original Rostock printer had the source CAD package, was used to develop substrate at a time, held at an angle until extruder mounted on the moving end the solid models, which were then sliced the substrate was completely covered. effector, whereas the three - axis stage with the 3D printing software Cura 25 and The slurry was remixed between used in this work was essentially a converted into G - code. G - code provided substrate coatings to minimize settling. Rostock turned upside down, with the numerical control to the stepper motors, The coated substrates were laid flat to workpiece on the moving end effector directing them when to move and how dry for approximately 30 minutes. and the “ extruder ” (welding gun) fixed in fast to move. The metal printer interfaced position above it. with these programs using a printer An aerosol - based boron nitride coating server developed at Michigan Tech with a (ZYP Coatings), approximately 5.9 μ m During this study, welding parameters web - based interface. 26 thick, was also sprayed directly onto the were set manually and the motion of the two substrate types. The coating stage was adjusted to produce a quality Materials Preparation and Printing thicknesses of aluminum oxide (18.8 μ m) bead. A quality bead was defined as a of Test Specimens and boron nitride (5.9 μ m) were chosen continuous line of 3D - printed material to prevent conductivity issues between with consistent profile. Argon shield gas Standard ER1100 aluminum GMAW the welder and substrate that might was used to minimize inclusions and wire, 0.030 inches (0.762 mm) in prevent arc formation and thus preclude spatter so as to produce a higher quality diameter, was used as the weld filament, welding. Four samples per treatment weld bead. Flux core wire was not utilized while degreased 1100 aluminum and condition were prepared. as it can leave a waste layer on top of the A36 low - carbon steel were used for the weld, making it difficult to print multiple print substrate materials. Three substrate Lap shear test samples were prepared layers. release mechanisms were tested, with aluminum substrate coupons incorporating the use of various coatings (50.8 × 76.2 × 6.35 mm 3 ) butted together Details of the Three - Axis Stage and substrate materials to modify with a 25.4 × 50.8 × 6.35 mm3 print made adhesion of the 3D - printed part (Table 1). The three - axis stage is shown in Figure 1. over the butt joint ( Figure 2 ). A sheet of An aluminum oxide coating, All of the designs for the hardware and 6.35 - mm - thick A36 low - carbon steel approximately 18.8 μ m thick, was applied all of the software employed are free was placed under the substrate plates to to the two substrate types. Coating and open - source. 22 The all - metal act as a heat sink. Relevant print thickness was calculated using an average construction 23 minimized risk of damage parameters, including cover gas, wire mass across the surface area of the feed rate, power, and slicing speed are due to weld spatter and heat.