Ceramic 3D Printer

MAE 435

October 19, 2016

Jeffrey Ellard

Melissa Falvy

Austin Jefferson

Jameria Randolph

Bryan Smith

Nicole Versis

Table of Contents

Abstract

Introduction

Completed Methods

Proposed Methods

Results

Discussion

Appendix A

Appendix B: CAD Drawings

Appendix C: Budget Analysis

Appendix D: Gantt Chart

List of Figures

Figure 1 - Ceramic 3D Printer Frame Design...... 8

Figure B.1 - Base: Front View2

Figure B.2 - Base Support: Front View2

Figure B.3 - Top Base Support: Front View3

Figure B.4 - Extruder Support: Front View3

Figure B.5 - Top Base: Front View4

Figure B.6 - Chain Guide: Front View4

Figure B.7 - Extruder Top: Front View5

Figure B.8–Slider Guide: Front View5

Figure C.1 - Budget Analysis Graph6

Figure D.1 - Gantt Chart9

List of Tables

Table 1 - Possible Clay Recipes...... 9

Table 2 - Possible Binder Recipes...... 9

Table 3 - Selected Clay And Binder Composition...... 9

Table A.1 - Parts List For Extruder/Nozzle Assembly

Table C.2 - Estimated Project Costs

Table C.3 - Budget Analysis

iii

Abstract:

Ceramic 3D printing offers the ability to design and create objects which would not otherwise be feasible using traditional methods.These methods include using a pottery wheel to sculpt an object to be fired in a kiln. This process requires time and skill to be achieved. By using a 3D printing method, the amount of time taken to produce an object is reduced. Also, the printer is capable of producing more complex geometries. A clay recipe consisting of various clay powders, maltodextrin, isopropyl alcohol and distilled water was developed which will be pushed through an extruder by compressed air. This clay recipe will be thoroughly mixed using a ball milling machine to ensure optimal results during printing. Without proper mixing, air bubbles or large chunks of clay could cause a clog in the extruder nozzle. This could cause anything from small defects in the material to major defects which may cause a collapse of the printed object. The consistency and viscosity of the clay will be tested to ensure the constructability of the material. Several different sized objects will be printed to test the limits of our printer and selected material. A control system was selected which will be programmed to create a ceramic object. The extruder will be guided using the stepper motors in this control system. A basic frame was designed which will support all these components.

Introduction:

Three dimensional (3D) printing uses a variety of materials, such as metals, plastics, ceramics, and concrete, to create an object for use in medical research, engineering, and other related fields of study and manufacturing [1]. The process of 3D printing is also referred to as additive manufacturing (AM), which is to create an object by adding material, layer by layer [1]. Delta 3D printers consist of a printhead that uses stepper motors to move along the x-, y-, and z-axes. A filament material of the user’s choice will pass through the printhead and onto the surface that the 3D object will be built on, otherwise known as the print bed. These parts are held together by the frame. In the past, 3D technology mainly dealt in plastic and metal processing, and not as much with ceramics. Printing 3D ceramics is a limited process because of concerns of resolution and quality of the end products capabilities [2]. Since there are limitations for ceramic technologies, problems may arise during the printing process. Some examples of common problems that may arise are the parts may malfunction or break because the proper guidelines weren’t followed, the clay object being printed could crumble under its own weight, and the thickness of the clay may clog the nozzle and cause damage to the other parts within the printer.

Determining the correct clay composition for 3D printers is a process of mixing various raw materials to get specific desired properties. These properties vary based on the ceramic powder recipe and the mixing method to obtain a porous mix and desired viscosity [2]. 3D printing ceramic material is becoming desirable because clay is readily available and automation manufacturing can reduce cost and eliminate waste compared to conventional manufacturing methods [3]. A past experiment successfully printed circular ceramic disks, but the objects displayed undesirable variations in strength and porosity [3]. Ceramic’s potential stems from its wide range of applications and material properties, however current suppliers do not provide clay powders and binder options for 3D printers to produce ceramics [4-6].

Every 3D printer requires a control system that consists of hardware, firmware, and software produces fluid and accurate motion of the extruder in order to successfully print individual layers and create objects [7]. These three subsystems together are able to control the movement of the extruder in the x, y, and z axes. The hardware must be capable of processing instructions from the firmware in order to control the speed of individual stepper motors, which in turn control the movement of the extruder [8]. Movement in the x and y axes is as accurate as possible since the extruder will be constantly moving in those axes, while only moving up in the z direction once every layer [9]. Many entry level and do it yourself 3D printers utilize an Arduino style board to carry out these tasks due to its simplicity and economical value [10, 11]. The control system also maintains proper flowrate of the material being printed. This is typically done by feeding the material through the printhead with an additional stepper motor and heating it up. However, the printer being designed for this project will require a new method for regulating the flow rate of the material in conjunction with the movement of the extruder itself since material will be controlled by an external tank of compressed air.

The extruder and nozzle of a ceramic 3D printer regulates the flow of clay and deposits this material to make a product. During this process, material is pushed through an extruder and the product is created layer by layer from the bottom up [12]. Proper flow and nozzle size are essential to producing a recognizable final product. The rate of flow of clay material depends on the viscosity of the clay as well as the pressure provided by the compressed air [4, 13]. Pre-fabricated extruder and nozzle assemblies are not available, so components must be adapted from the adhesives industry to suit the needs of the printer.

The ability to reproduce designs about 50-70% faster as compared to traditional methods, make 3D ceramic printing a growing industry [6]. Ceramic 3D printers currently being produced are intended for commercial use and suppliers do not carry or offer a specific clay material designed for 3D ceramic printing [14]. The purpose of this project is to design and construct a 3D printer which will use an extruder to deposit clay material at the desired flow rate using compressed air in order to create a ceramic piece.

Completed Methods:

The frame and supporting framework were modeled in Inventor (Autodesk, Inc., San Rafael, CA). These parts consist of the bottom base, top base, bottom base supports, top base supports, bottom extruder support, top extruder support, chain guides, and slider guides. These parts have dimensions in inches and are of acrylic material. Assembly modeling in Inventor was completed to ensure parts constrained together without any defects. The files were then sent to Old Dominion University’s Machine Shop for production.

After researching suitable clay compositions for 3D printing, three recipes were selected for clay options and two were selected as possible binders. The binder acts as an adhesive and gives consistency to the clay for constructability. The clay composition selected was: 68% (red art, ball clay, gold art, feldspar, silica), 16% maltodextrin, and 16% powdered sugar. The binder composition selected was: 750 ml isopropyl alcohol and 1500 ml distilled water. Once all the raw materials were selected, a ball milling machine was chosen as a mixing method because of its availability and history with blending ceramics. If a ball mill is unavailable, traditional hand mixing techniques may suffice. This machine rotates a bottle that encapsulates the raw materials with grinding balls. After consulting with the advanced materials lab, 16 oz polypropylene graduated bottles were selected to encapsulate 5mm lead-free glass grinding media with the raw materials. The first experiment comprised of measuring each raw material by weight on a digital scale and adding each to the same graduated bottle. The grinding media was then added last before preparing the ball mill for mixture. However, upon inspection the mixture appeared very thin and runny. This caused the experiment to cease, and indicated a need for modifications to the clay composition.

An extruder was selected which can be loaded with clay and use compressed air to push this material through a nozzle. The extruder uses a cartridge which is loaded with clay and placed in a retainer which reinforces the cartridge structure so it does not deform when pressure is applied. A small cap at the tip of the cartridge allows the nozzle to be attached. A retainer cap is required to attach the compressed air to the top of the retainer and cartridge. The recommended nozzles were found to be between gauges 13-18 depending on the consistency of clay used and level of desired detail [1]. All of these components are originally intended to work with adhesives, but can be adapted, for our purposes, to use clay. The extruder has been assembled and will be installed when frame assembly is completed.

The main hardware components of the control system consist of the following components: RAMPS 1.4 shield (Quimat model QK-17 US), Arduino Mega 2560 board (Quimat model QK-17 US), LCD interface (Quimat model QK-17 US), stepper motors (Stepper Online 45 N*cm), gears (DROK 16 teeth 5mm bore), belts (HICTOP 5 meters), and a power supply (Logisys Corp. model PS480D2). Along with the hardware, Repetier firmware (Hot World GmbH & Co. KG, Willich, Germany) can be used to control individual stepper motors. The Blender software (Blender Institute BV, Amsterdam, Netherlands) can be used to create 3D objects which can be exported to the Repetier Host (Hot World GmbH & Co. KG, Willich, Germany) to “slice” them so that individual layers can be printed. Once a complete parts list was constructed, research transitioned to proper wiring of the circuit boards. A wiring guide for a RAMPS 1.4 board was downloaded from a popular 3D printing website and was used to identify the proper configuration of the board [15]. All of the required control components have been purchased and received expect the RAMPS 1.4 kit. The stepper motors have been wired to four pin connectors and the pulley gears have been attached. The endstops have also been wired to two pin connectors so that when the control board arrives, all components can be easily attached.

Proposed Methods:

Before assembly begins, to catch manufacturing flaws, the dimensions of the machined parts will be compared to their CAD drawings. Next it is necessary to gather all of the purchased and machined parts and make sure that the dimensions are correct and that there aren’t any flaws/issues with the parts. Assemble all of the pieces together and build the outside structure of the printer. Once the structure is built, attach all of the motors and other electrical equipment. The extruder will be attached to the printer. Finally, before the clay testing phase, the structure of the printer will be examined to ensure it is sturdy, the motors will be checked to make sure they run without interference, and adjustments will be made as needed.

To complete the development of the clay composition, analyze the ball mill for correct functionality and cleanliness. This analysis could include, running the ball mill at a desired speed, length of time, and visibly inspecting for old residue. After the analysis is finished, mix the raw materials on a ball mill for 4-8 hours, following the manufacturer’s instructions to get a finished clay composition. Finally, adjust the mix of raw materials as needed based upon testing results. This adjustment will include adding more clay, reducing the water and alcohol content, and possibly applying an enhancer during the ball milling process.

After a suitable clay recipe is selected, testing will begin to determine the flow rate of the clay which will sync up with the stepper motors. An algorithm for the modulation of this flow rate will be developed. This may include modification of clay consistency, air pressure or nozzle size. Trial and error will be used to select the appropriate nozzle gauge. The nozzle gauge will also be dependent on the type of object being printed. A more detailed design will require a larger gauge. Once the desired flow rate and clay consistencies are established, the extruder will be attached to the main body of the printer (Figure 1). Care will be taken so the air hose assembly does not interfere with the movement of the control system.

For the control systems, the RAMPS 1.4 assembly guide will be followed in order to ensure that the RAMPS shield and Arduino are connected properly with the stepper motors and end stops. Once the circuit board is wired and the firmware is downloaded to the board, the three stepper motors will be mounted on the printer structure so that each one controls one arm of the printhead. The belt and gear system will then be attached to each motor to control the movement of individual arms. The printer will then be tested without the extruder in order to adjust the firmware parameters so fluid motion is created when the three motors are operating simultaneously. After printhead calibration, testing parameters of the installed extruder will include flow rate adjustments with print head speed. This part of the project will most likely come down to trial and error with adjustments being made by following a flow chart diagnosis. Also, a solenoid operated control valve is being explored as an option to regulate initial pressure to the extruder as well as isolating the extruder once the print has finished.

After the clay composition is finished mixing in the ball-milling machine, it will need to be tested with the extruder and nozzle to ensure that it is smooth enough to pass through the nozzle without clogging it. Experimenting with different flow rates of the clay will occur in order to find the correct pressure to move the clay through the extruder. Once the control system is working properly, the printer will be tested. A 3D drawing of a simple shape will be made in Autodesk Inventor. This drawing will represent a potential product to be made by the printer. The drawing will be sent to the printer to see how the motors move and if there are any issues with the control systems. Any glitches or issues will be fixed before moving onto testing the printer as a whole. If the control systems work as expected, all of the pieces of the printer will come together. A final test will be run to ensure that the printer support structure, clay composition, extruder and nozzle, and control systems all work in sync with each other. This test will be actually printing a green state object. A green state object is the clay in its soft state before being fired. If all goes well with printing, the green state object will be moved by hand to the furnace and hardened by the heat. After firing, the object will be checked over for cracks, shrinkage, or other deformities and the testing process will be repeated until our final product is of acceptable quality.

Results:

Downloads Assembly1 jpg

Figure 1 - Ceramic 3D Printer Frame Design

Based on a delta-type 3D printer part selection was finalized on price. U.S. Customary units was used and parts were modeled in Inventor. Acrylic was chosen to be used as the bottom base, top base, extruder support, extruder base, chain guides, and slider guides (Figures B.1-B.6). Aluminum was selected for bottom and top base supports (Figures B.7-B.8). Stainless steel ASTM A581/582 was ordered to be used as the frame support. A parts list was constructed which details all extruder and nozzle components (Table A.1).

Table 1 - Possible Clay Recipes

Table 2 - Possible Binder Recipes

Table 3 - Selected Clay And Binder Composition

After researching traditional ceramic compositions and analyzing the requirements to 3D print ceramics using an extruder design, multiple recipes were chosen for consideration. Three possible clay powder recipes and two binder recipes were developed based on previous experiments with a common goal to 3D print ceramic material (Table 1,2) [3]. From these recipes, a final theoretical clay and binder composition was selected (Table3). This selection was based on the raw material’s quality, cost and availability.

Discussion:

As 3D printing becomes more accessible to the general public, and the technology continues to evolve, it is important to develop printers capable of printing materials other than traditional plastic. The development of a printer capable of printing ceramic materials will allow research to progress so that complex components such as fuel cells can be printed one day. While there are commercially available 3D printers capable of printing ceramic materials, they are not widely available due to their high cost which stems from the advanced control and extruder systems as well as their novelty. The purpose of this project was to develop a prototype 3D printer capable of printing ceramic materials with a budget of $1,500 that could be replicated by other senior engineering students.