Reference no: EM133196895

Design Project

This is an important materials and manufacturing project that will test your engineering skills and ability to select appropriate materials for a design of your making. You will need to be familiar with the manufacturing methods required to produce all components for your project, and you will need to describe the process sequence(s) for fabricating each component in your design. Your will also 3D-print a prototype of your design.

SLS Powder Dispensing System: Design a Powder Delivery Mechanism with Mass or Volume Controls for Sprinkling Powder into Flowing Gas Streams.

Imagine that you will be given a small hopper, like that shown in Fig. 1 (left). A fine powder will be loaded into the hopper. These powders are the source material for a new selective laser sintering (SLS) additive manufacturing system. Your job will be to dispense the powder into a flowing gas and focus the two-phase flow at a particular point (the laser focus), as shown in Fig. 1 (right). The more tightly you can focus the flow, the better.

Because the powders are roughly 500 nm diameter particles, they will tend to stick to one another and cluster into larger agglomerates. This is due to Van der Waals and electrostatic forces. And because of the presence of water can make particle adhesion even worse, the powders must also be kept dry in inert argon gas until dispensed.

The powders are non-Newtonian fluids, meaning that they behave like both solids and liquids. Ketchup and powdered sugar are good examples of non-Newtonian fluids. You can use powdered sugar as a surrogate for this powder. When stationary, the particles' viscosity is much higher than when they are in motion. So, once you start them moving you will want to keep them in motion (or they will stick and stop moving). It is a good idea to use vibrations to keep them in motion.

Your job as a manufacturing engineer is to create a dispensing mechanism with a miniature glass hopper that adds small, measured quantities of powder into an argon gas flow in a continuous manner. To perform high-quality 3-D printing, the amount of powder injected into the gas flow should be as constant as possible over time.

Because the powder has a known density and void fraction in the glass hopper, you can choose to measure out the powder either by volume or by mass (your choice). The glass powder hopper shown in Fig. 1 is just an example; your solution can be whatever you think will work best-and you will need to work out the hopper's optimal geometry, components, and controls. But, you will need to minimize the size and mass of the hopper and dispenser unit, as they will have to be deployed as a compact unit that moves around quickly with the laser system; the entire powder dispensing package must fit within a tube that is 20 mm in diameter x 65 mm long.

For this project, all you are doing is designing a new powder dispenser and hopper. You don't need to worry about how the hopper gets loaded with powder-another engineer is working these problems. You just need to develop a mechanism that provides the correct amount of powder into the gas flow (at a constant dispensing rate) and focuses it at the correct distance.

What you Should Do First:
• Brainstorm potential designs for the dispensing system (at least 6 very different designs). We are looking for creativity.
• Perform calculations to determine the size of the hopper and calculate the mass of all system components.
• Calculate hopper emptying times for different dispensing rates (within the range provided), and volume & mass fractions of the powder relative to argon in a 500 sccm argon flow (at different dispensing rates). Make plots of these parameters vs. dispensing rates.
• Review the literature to find multiple ways to consistently control the motion of a powder (e.g. powdered-sugar). Send Prof. Maxwell copies of any good articles you find to [email protected].
• Review the literature to find various mechanisms that will move powder from a hopper into a gas flow in a measured way.
• Review the literature to determine the best angles at the bottom of the hopper to ensure a good flow without powder stiction to the walls. Use this to help design the hopper.
• Review the literature to find multiple ways to measure the powder's mass or volume as it is being dispensed.
• Decide which sensors and actuators you will need and locate sources for them online.
• Minimize the size/mass of the delivery mechanism through careful mechanism and materials selection, so that it can fit within the size specified.

Section II: How You Should Approach This Project:

You will need to follow closely the engineering design process given above (Fig. 2), from the onset to the end of the project, while skipping the testing and iteration steps (for lack of time to fully carry these out). This project will teach you to: (1) identify the challenges associated with your project topic (i.e. define the problem), (2) search in the literature for what others have done, (3) use creativity and brainstorming to find your own solutions, (4) evaluate your solutions and perform calculations to see if your solution will work, and then
(5) further develop this solution, adding important details, e.g. dimensions, tolerances, materials, CAD drawings, etc. It is assumed that at least one member of your team is capable of creating computer-generated engineering drawings or at least detailed hand-drawings with dimensions. This will result in a 3D-printed prototype of your solution. Finally, during step (6), you will communicate your selected design and summarize your work by generating an oral group project/final defence.

Section III: Group Project Instructions:

Tasks to complete for your project:
• Form a team of 2-3 individuals in LMS, using the group project selection link provided. You cannot do this project alone. Even if you don't know anyone, please sign up for a project based on a topic that most interests you. A minimum of two individuals can work on a project, but it is recommended that you form three person teams to lower the workload. Four person teams are not allowed, unless organized by the instructor.
• If you cannot meet in person, arrange how you will work electronically/remotely with these individuals (exchange phone numbers, emails, arrange Zoom meeting IDs, etc.). This should be done by the 2nd week of the semester. You should all be meeting at least once weekly throughout the semester. If you cannot contact a teammate for over 1 week, please email the subject coordinator ASAP, so he can remove this individual from your team. No freeloaders are allowed. Anyone who does not contribute to their project will fail the final defence (and likely the subject).
• Divide the design engineering and report writing tasks evenly amongst yourselves. You must use the roles described in the first workshop, i.e. (1) brainstormer, (2) functional designer, & (3) manufacturer.
• Work together for each phase of the design project (each step in Fig. 1): determine the performance criteria and bounds for the solution, brainstorm your collective ideas, document them, analyse them, and choose your winning design; justify your choice for the solution by providing calculations of anticipated performance--this should include a calculation of the final assembled mass of your system and graphs of dispensing rates, and volume & mass fractions of the powder in the flow.
• Put additional details into your design choice--this should include engineering drawings with dimensions, tolerances, and materials for each component. Provide detailed CAD or hand drawings with dimensions for each component (your own work).
• Commercial components should be selected for the actuators and sensors, and their costs and sources documented.
• Create a 3D-printed scale model of your solution that can be 3D printed in less than ½ day (in total) and take images of the printed components and assembled design. Printed parts can substitute for commercial components, where needed.

• Finally, provide a "workable process sequence" to fabricate each custom component, Explain how you are minimizing mass and optimizing performance for each component. You should also explain how the materials are sustainable (if they are), and discuss any waste streams that may result from the process(es).

Tasks to complete for your defence:
• Prepare a set of PowerPoint slides (8 slides) for your role in the project. as described below (and in Workshop 1):

Role 1: The Brainstormer:
o Slide 1: Introduction: Project description and background w/ lit. search.
o Slide 2: Problem statement and description of what the solution needs to provide, including any constraints on the design.
o Slides 3-6: Collection of solutions brainstorming & description of potential designs.
o Slides 7-8 Rationale for down-selection to a particular prototype.

Role 2: The Designer/Analyser:
o Slides 1-3: Detailed description of selected design, including CAD drawings,
o Slides 4-5: Discussion of potential materials to be used in the design, and rationale for materials selection (including emergent properties).
o Slides 6-8: Calculations & plots showing anticipated performance with these materials and design.

Role 3: The Manufacturer:
o Slide 1: Manufacturability of the selected design; what is difficult and what is not?
o Slides 2-5: Develop/discuss the detailed fabrication/assembly sequence(s), using flowcharts and drawings.
o Slide 6-7: Images of 3D-Printed components and assembled system.
o Slide 8: Rationale as to why these process sequences are feasible, safe, sustainable, and do not harm the environment. Are there risks associated with the manufacture of this design or the processes used?
o After Presentation: List of References (>15).

• Note that a common "title page" for your project should be added to these slides (for each role) and is excluded from the page count. Also note that your name and group title must appear on each slide of your presentation (either in the header or footer) to receive credit. A list of references is also excluded from the slide count.
• You should upload these slides into the Turnitin link provided in LMS within the Group Project & Defence folder.
• Prepare a brief outline of what you would like to say during your presentation. Pretend you are teaching another person about your project. Practice using this outline until you feel you can teach the topic to someone else without looking down at your notes constantly.
• Next, using your PowerPoint slides, record a video presentation that supports/defends your proposed solution to the engineering problem. This is limited to your role in the project. For credit, your entire face must be visible during the recording at all times. Your voice must be clear and understandable, and the slides must be readable.

• Your recording must be uploaded as a single (mpeg or mp4) file into the link provided within the LMS Group Project & Defence folder. Each team member will upload their own recording according for their role (100 Mb maximum). This recording should not include the topics covered by other team members.
• When combined, the recordings from all team members should completely describe the problem, the design process used, the team's solution, and the manufacturing processes that are proposed to fabricate the solution. This should include all of the roles 1-3 described above. The group cannot receive full credit otherwise. This would be a total of 24 slides, plus cover page and references, if we were to combine it into a single presentation.

Attachment:- Design Projects.rar