DESIGN AND FABRICATION OF POWDER BASED BINDER JETTING …€¦ · DOI:...

DOI : 10.23883/IJRTER.2017.3441.BNTSR 142

DESIGN AND FABRICATION OF POWDER BASED BINDER

JETTING 3D PRINTER

Balakrishna.G1, Praveen Kumar B.C

2, Hubert Johnson Rodrigues

3, Lakshmikishor ds

4,

Mohammed Hubaish5

1Asst. Professor, Department of ME, Atria Institute of Technology,

2Asst.Professor, Department of ME, Atria Institute of Technology,

3Department of ME, Atria Institute of Technology,

4Department of ME, Atria Institute of Technology,

5 Department of ME, Atria Institute of Technology

Abstract— Additive Manufacturing of components via Binder jetting enables the production of complex geometries. The objective of this work is to fabricate and carry out trails on a powder-based three dimensional printer. During the work a prototype system was manufactured and, during subsequent testing, was found to successfully print objects by applying a binder to multi-mode gypsum based powder. During binder jetting, a polymer binder (Bentonite, dextrin, edible oil, water, resins) is printed onto a bed of powder using a traditional inkjet print head to form one cross-sectional layer of the part. After a layer of binder is printed, the powder bed lowers, and fresh powder is spread over the powder bed atop the previous layer. In this manner, the object is constructed layer by layer. After the part is printed, the excess powder is removed using compressed air or vacuum, it is simple for an end user to perform.

Keywords: Binder jetting, Corexy, Piston mechanism, S.T.L file

I. INTRODUCTION

Rapid prototyping is a group of techniques used to quickly fabricate a scale model of a physical part or assembly using three-dimensional computer Aided CAD data. Construction of the part or assembly is usually done using 3D Printing or "additive layer manufacturing" technology [1].As with CNC subtractive methods, the computer-aided-design-computer-aided manufacturing CAD-CAM workflow in the traditional Rapid Prototyping process starts with the creation of geometric data, either as a 3D solid using a CAD workstation, or 2D slices using a scanning device. For RP this data must represent a valid geometric model namely, one whose boundary surfaces enclose a finite volume, contains no holes exposing the interior, and do not fold back on themselves. In other words, the object must have an “inside” The model is valid if for each point in 3D space the computer can determine uniquely whether that point lies inside or outside the boundary surface of the model. CAD post-processors will approximate the application vendors’ internal CAD geometric forms with a simplified mathematical form, which in turn is expressed in a specified data format which is a common feature in Additive Manufacturing STL (stereolithography) a standard for transferring solid geometric models to machines. To obtain the necessary motion control trajectories to drive the actual machine, Rapid Prototyping, 3D Printing or Additive Manufacturing mechanism, the prepared geometric model is typically sliced into layers, and the slices are scanned into lines producing a "2D drawing" used to generate trajectory as in CNC`s tool path, mimicking in reverse the layer-to-layer physical building process.The binder jetting uses a nozzle jet to print layers onto a print medium.

International Journal of Recent Trends in Engineering & Research (IJRTER)

Volume 03, Issue 09; September - 2017 [ISSN: 2455-1457]

@IJRTER-2017, All Rights Reserved 143

As the technology progresses and the new materials become available, the field of rapid prototyping becomes a more viable option in a market saturated by traditional machining processes.

II. LITERATURE SURVEY

Binder jetting was developed by Ely Sachs and Mike Cima at the Massachusetts Institute of Technology in 1993 and Z Corporation obtained an exclusive license for the process in 1995. [2] The z printers as it is now called have become one of the most popular commercial 3D printer lines available. The binder jetting printer was featured in episode of CSI: NY.Z. Corporation was acquired by 3d printer systems on January 3, 3012. 3D Systems was founded in 1986 by chuck hull, the creator of 3D printing. Chuck Hull also invented rapid prototyping technology and the STL file format. 3D Systems specializes in several aspects of 3D printing, including 3D printers, print materials, software, and custom-parts services.

Colorpod is another project, the culmination of decades of work. [3] It was developed by Aad van der Geest. Since 1992 he has been an independent product designer with various experiments and projects to his name. From very big projects in the agricultural sector to the very small, like special calculators, were tackled by Aad. In the early '90s Aad heard about rapid prototyping and 3D printing for the very first time. He found it really fascinating but just couldn’t get involved because of the price tag. Being an inventor, Aad knew what he had to do: he had to invent his own. He proceeded to spend a lot of time experimenting and trying out various approaches. Aad’s first idea was a sand and plaster machine. It took him over a year to realize this idea, but he successfully did it. This was Aad’s first introduction to building a CNC machine and controlling stepper motors. This project was a great process that helped him get more familiar with the mechanics, but the outcome still wasn’t great due to difficulties with reliability and not getting strong, functional models. But invention isn’t about getting it right first time and the entire experience led to a color 3D printer which was the true predecessor of the Colorpod. Ingeniously, to create this color 3D printer he used the mechanics of a regular 2D printer, so he could fully focus on the materials and print results. There are other companies which produce inkjet based binder jetting machines for high end manufacturing such as [4]voxeljet, [5] exone. To a small scale 3d printer the companies like plan-B, PWDr, P3P were developed around the globe, the plan-B version of printer was analyzed to develop our machine.

III. WORKING PRINCIPLE

Figure 1: Work flow diagram of binder jetting 3D printer




The machine consists mainly four parts: - Body of the machine, piston ramps (build and feed pistons)[6], counter rotating roller mechanism, CoreXY mechanism, gantry with binder extruder. Functional analysis diagram is discussed below 1. Step powder 2. Spread powder layer 3. Queue current 4. Move print carriage 5. Printing Material inputs and outputs to the system, represented by the dashed line, are thick arrows, while information inputs and outputs are represented by thin arrows.

IV. PROPOSED MODEL OF A BINDER JETTING 3D PRINTER

The complete design of the printing machine was studied [7],[8]and follow observations were made. The printing machine has mainly five sub assemblies, they are:

1. Encloser 2. Piston(z-axis) 3. Spreader 4. CoreXY(XY-axis) 5. Printhead jet (gantry)

4.1. Encloser: Body of the machine is an enclosed rigid structure which provides space to place the other mechanisms.

4.2. Piston Ramps: Piston is the ramp which move up and down in z axis at defined space, there are two types of pistons,a) Build piston: where the product is built b) Feed pistons: powder is fed to roller in order to spread over build piston. The feed piston volume is more compared to build piston because to fill the build ramp completely with powder and then move remaining powder to waste bin. 4.3. Spreader: It is a counter rotating roller which moves in x-axis of the gantry and distributes the powder evenly, if the powder is not even then the density of the layers will be not isotropic which may result in formation of residual stress in the components that has been printed .The roller must touch the surface of the chamber in order to achieve uniform spreading of powder on the bed. The spreader mechanism has to gears which are externally meshed one is smaller and other is bigger which then mesh with the rack place below the gear box. It has drive side and driven side, drive side is where the gear box is place. The gear box is derived with a Nema 17 stepper motor coupled to the shaft of the bigger gear . 4.4. CoreXY (XY-axis): In order to move the gantry in XY axis corexy mechanism plays a important role. It is basically a belt driven mechanism which has 10 pulleys in which two are driven by Nema17 stepper motors .When the two motors rotates in same direction then gantry moves in opposite direction(x-axis).when two motors rotates in opposite direction the gantry moves is y axis. Also when single motor rotates the gantry moves diagonally. CoreXY provides a fundamental building block of many computerized fabrication tools - Cartesian motion in a simple and adaptable format. 4.5. Printhead jet: The design of Printhead jet is the part which holds the binder inside the tube with a plunger to push the binder in a determined rate mainly at 100mm per second of velocity and diameter of the nozzle is kept at 0.4 therefore 12.566 cubic millimeters per second was the flow rate.




The plunger is coupled to a simple coupling and a M5 lead screw actuates the plunger up and down as the stepper motor rotates clockwise and counter clockwise direction.

Figure 2: Model of binder jetting 3d printer in catia v5 workbench

V. FABRICATION OF THE BINDER JETTING 3D PRINTER

5.1. Encloser: The fabrication starts with cutting down 15mm thickness plywood of about 1500×2000mm to 560mm×473mm rectangular shaped two boards. Two plywood is then cut with jigsaw machine as ‘U’ shaped ways to fix the linear rail; the marking is 40mm×60mm on driven side and 85mm×60mm on drive side.

All 15mm and 10mm cut pieces are treated with surface coating by knife filler materials to enhance the life of the structure and give a good surface finish then the surface is grinded with 180number

Figure 3: Unfinished chamber sections




emery paper. Finally, the pieces are coated with blue and white themed surface coating which is shown below

Figure 4:Encloser

5.2.Piston: The fabrication of pistons starts with cutting down the two pieces of 10mm plywood,1mm thickness expanded polyethylene,3mm thickness polypropylene in 200mm×200mm and 230mm×200mm.2 number of M10 lead screw is cut using a hand cutting machine for a length of 20mm and then one end of each lead screw is grooved in lathe reducing overall diameter of the groove to 8mm and turning was done until 10mm length and ensured that the fit with jaw coupling was a press fit. Since the piston top and lead screw is linearly connected a flange connector is used which was made of PVC material, with that 68mm diameter tube is inserted inside the flange. All the cut pieces of piston ramp are joined to flange connector with the M3×15mm screws and nuts. The layer must be placed as specified, based layer id plywood which is rigid and can hold the powder materials weight next layer is EPE which provides a seal by avoiding the powder being spilled out of the chambers, the top one is polypropylene for a good ramp surface and also sandwich the EPE material. The 68 diameter tube is made to hold a T-nut which supports the lead screw to rotate and move inside easily up and down. A mini jaw coupling is used to connect the stepper motor to lead screw with garb screw

Figure 5:Piston




5.3. Linear rail: Linear rails are the aluminum extrusions, the cross-sectional area is 30mm×30mm×3mm. It is mounted on either side of the chamber to guide the roller freely in a specific path. The linear rails are bolted at the ends where it has high load bearing capacity. The rail assembly also includes 4 end brackets with Ø8mm holes in it 15mm from top to correctly place the gear box assembly. An Ø10mm aluminum rod is used as linear guide.

Figure 6:Linear rail

The brackets were installed with M3 screw on to the extruded L angle at each ends. A clearance of 0.5 is provided from the extruded L angles to the brackets which are to have a proper traction for the gear box to hold the gear in place without the slippage.

5.4. Gear box: The fabrication of gear box starts with using the polypropylene 8mm sheet and cutting them to a size of 50×130mm. The requirement for such pieces to build gear box is 2 numbers. These two polypropylene will serve as the side walls of gear box which support the two gear system. The other side i.e. along the width of the gear box two aluminum housing is build which consists of hole which is drilled with Ø18.5mm drill bit, in order to hold the linear bearings in place the hole is made as interference fit type inserts and then a M3 tap was put from the top of the housing to hold the linear bearing in place at operating conditions. Further, the mounting of 2 bearings is carried along as a hole of Ø21.2mm.The space has been provided for the stepper motor mount meanwhile a gear which is a drive is attached to the shaft of the motor.

Figure 7:Gearbox




5.5. Printhead Jet: One of the sophisticated parts in the machine is the binder injection tube which plunger and nozzle tip. A medical syringe is used for this purpose, which can hold around 20ml of binder enough to produce a single object. The syringe is modified to push out the binder as in required rate of flow rate. A nozzle tip of FDM machine is attached of diameter 0.4 which can be changed to further minimum diameter for layer thickness. The plunger in the sleeve is actuated by a lead screw which is M5 complete on the stoke length. A motor is mounted on above the gantry to turn the plunger for extrusion of the materials out of the nozzle.

Figure 8:Printhead jet

5.6. CoreXY: The parts which are fabricated need to be assembled to contribute the whole system, therefore the parts are attached as the steps provided below. Join the 50mm×50mm pillar plates at the top and below the pillar. Insert the 10mm dia stainless steel guide rod into the holes provided at top of the pillar, a grub screw is fastened to ensure the fit .Guide blocks are inserted with 4 number linear bearings and also fastened by the grub screw to have a rigid fix. On to the guide block two stainless steel rods are firmly fixed which provide the way for y axis linear movement. The gantry is inserted into the Y axis and a smooth motion as expected is ensured. On the top of the pillar however, a stepper motor mounts are used to mount the stepper motor which are held by 4 head screws. The driven side has 4 number 20 teeth pulleys 2 at each end fastened in as per the design provided. After all the components are attached, a timing belt is leaded through the pattern of corexy mechanism. As well as, the base of the pillar is fastened by 4 number socket screws and nut to hold the complete assembly of corexy. Finally, nozzle is fixed on to the gantry for extrusion of the binders from the machine nozzle tip. Completely assembled 3d printer with cad model is shown below




Figure 9:Complete assembly of printer

5.7. Hardware: The entire control system of binder jetting 3D machine consists of following electrical hardware components;

• Arduino micro controller

• RAMPS 1.4

• A4988 stepper motor drivers

• Ends stops

• Stepper motors

5.8. Software: It is a part of a control system that consists of data or computer instructions, in contrast to the physical hardware from which the system is built. In computer science and software engineering, computer software is all information processed by computer systems, programs and data. control software includes computer programs, libraries and related non-executable data, such as online documentation or digital media. Computer hardware and software require each other and neither can be realistically used on its own. There are two types of software used on this project that is

• Repitier host

• Adruino IDE 1.8.2

VI. OBJECTIVES

The objective of this work is to design and prototype a powder-based three-dimensional printer.

• To produce the machine from design to reality.

• To fabricate the components according to design criteria.

• To assemble the final fabricated parts.

• To ensure that mechanisms are working as per predefined design.

• To successfully run the machine with all mechanisms combined

VII. CONCLUSION

Analysis and redesigning have been done repeatedly to give accurate end results and satisfactory output. The work main objective was to develop a 3d printer with complete powder printing results. This was accomplished by means of recreating the previous designs iteratively giving provisions for fabrications for its respective dimensions. The design which we have finally done is completed with




desired output having infrastructural qualities of a binder jetting 3D printer. The model was found to be appropriate. The materials selected were available easily and were feasible also.

REFERENCES I. “Google Ngram of the terms rapid prototyping, additive manufacturing”

II. https://www.3dsystems.com/solutions- z corp III. https://3dprint.com/125361/colorpod-full-color-converter/ - color pod IV. http://www.voxeljet.com/materials/ -voxeljet V. http://www.exone.com – exone M-plex

VI. “Lightweight Metal Cellular Structures Fabricated Via 3D printing of sand cast molds”- D. Snelling, Q. Li, N. Meisel, C.B. Williams, R.C.Batra, A .P.Druschitz.

VII. Design of Machine Elements- V B Bhandari VIII. Materials Science and Engineering 2ND Second Edition- William Callister

DESIGN AND FABRICATION OF POWDER BASED BINDER JETTING …€¦ · DOI:...

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