Beginning of Project

For an updated project description, click on the following link for the Project Readiness Package.

Background

3D printing, or also known as additive manufacturing, is a process that creates 3-dimensional solid objects from a digital file. Through additive processes layers of material are laid down under computer control to create these 3D objects.1 Most 3D printers use FDM process, fused deposition modeling, which is a process that pushes thermoplastic filament through a heated barrel where it then melts. The plastic then moves through a small diameter nozzle. This technology has widely grown within the past 2-3 years due to the FDM process and the large amount of low cost printers. The future state of this technology will use unmodified plastic injection molding pellets which will benefit the 3D printing community by dramatically reducing the cost of consumable materials, will allow much wider range of materials used, and will allow high performance materials to be used.

The goals of this project are to design, prototype, and demonstrate a new 3Dprint head that can use ordinary plastic injection molding pellets as the feedstock. It should withstand up to 380°C, is reliable and functioning for 10 hours without failure, and has interchangeable extrusion nozzles that are of roughly 75 mm cube and 1kg mass, with different diameter holes. This print head needs to be able to work with standard hobby grade 3D printer control electronics.

1- What it is 3D printing? (n.d.). Retrieved September 2, 2014, from http://3dprinting.com/what-is-3d-printing/#whatitis

Problem Definition

At the beginning of the project, our team was tasked with determining customer and engineering requirements to narrow down the scope of the project. Benchmarking was considered to compare and contrast our system with existing solutions. The results can be found on the Problem Definition

Systems Design

With benchmarking complete, it was then possible to begin concept generation. Using functional decomposition and Pugh analysis, a number of concepts were created. Feasibility was performed for selected concepts to eliminate some of the least feasible ones. A list of risks associated with the project was developed to keep the project within scope and prevent any major failures in the future. Results of these efforts can be found on the Systems Design page.

Subsystems Design

During the subsystem design phase, the primary focus was to refine concepts, and go into more depth with research and feasibility for sub-level components. Meetings with subject matter experts (SME's) also took place during this time frame, to aid the team in completing feasibility analysis. Subsystems information can also be found on the Systems Design page, as well as Detailed Design.

Detailed Design

After generating concepts of the system and its components, detailed models of systems elements can be created. Components for heating, pellet storage, and pellet driving were selected and modeled. Proof of concept for an auger screw was performed, and additional analysis for heating, pumping, and screw driving was completed. Information regarding more detailed process can be found in Detailed Design

Complete Design

In the complete design phase, components from the detailed design were refined and re-analyzed as necessary. Full assembly models and drawings were created using Solidworks, and additional testing plans were developed. Most of this information is located in Detailed Design. During this phase the Gate Review was conducted; information for this can be found in Gate Reviews

Component Purchasing

This phase marks the transition from MSD I and MSD II. The bulk of parts purchased were raw materials or electrical components. Longer lead items were purchased first, and items that were uncertain in design or specification were held off from purchasing until further verification could be done.

Component Fabrication

When parts started arriving, most of the team's time was spent in the machine shop manufacturing the components of the printer head. When the team approached the machine shop staff, some design changes were made to make machining certain components easier, and to simplify the design.

System Construction

After some of the machining was completed, it was possible to start assembling the print head in order to carry out basic testing. Once a sufficient amount of the components are fabricated, more testing will be able to be done, and any changes to design or components can be made.

Testing

More extensive testing was carried out, and more issues began to arise with the system. For example, the bearing oil was evaporating due to the heat from the test, so a design change was made to replace the bearing with bushings instead, which do not have rubber or oil. It was also discovered during this time that the motor would be much too large to mount on a 3D Printer, so an external rig is required to be fabricated.

Additional Testing and Fabrication

During testing, many issues arose due to design flaw or unexpected results. As the part requirements changed due to feasibility issues, the design changed to follow. An even larger motor was selected for use, and the test rig design was finalized. A need for a temperature controller also arose, and parts were selected for creation of one. A new and improved screw came in, so the design changed even more to accommodate it. To replace the rubber sealed bearing, a sleeve bearing with graphite insert was chosen. Finally, construction of the rig began, and once it is completed testing can resume.

Final Testing and Results

During testing with the motor it was determined that the Arduino would be insufficient to control the larger motor, so an external motor driver was required. The first test with plastic began to yield promising results, until a binding nearly destroyed the assembly. This led to a slight rebuild and as a consequence, only performing dry runs at Imagine RIT. After Imagine, the tests were completed, and material was able to flow out of the nozzle. Another design challenge that arose was the pressure involved in the process. During one test, excessive pressure generated by the small opening of the nozzle proved to be difficult for the built in tolerance between the nozzle and the screw to handle, and caused stagnation of material. Removing the nozzle remedied this issue. Final documentation can be found in Publications & Presentations

Project Name

High Temperature Pellet Based 3D Printer Head

Project Number

P15551

Project Family

Printing and Imaging Systems

Start Term

2141

End Term

2145

Faculty Guide

John Kaemmerlen

Phone:585-475-2767

Email: jxkpdm@rit.edu

Primary Customer

Denis Cormier

Phone:585-475-2713

Email: drceie@rit.edu

Sponsor (financial support)

Denis Cormier

Photo Gallery

Planning & Execution

Gate Reviews

Problem Definition

Customer Interview

Systems Design

Detailed Design

Project Review

Build, Test, Document

Publications & Presentations