High Temperature Pellet Based 3D Printer Head

System-Level Design ReviewAlyssa, Kylan, Jimmy, Ray

10/02/2014

Questions to be resolved 1. Do you think our concept is feasible?

2. Do you feel the engineering requirements are complete?

3. Are we missing any risks?

4. How fine (+ or - 5%/2%) do you think we should be able to grind the pellets? (full size pellets to powder)

Current Product

3dprintingsystems.freshdesk.com 3dprintingsystems.freshdesk.com

Problem Statement● Current state:

○ 3D printer heads use plastic filament, which has variable diameter and is quite expensive

○ If the diameter varies too much, the feed mechanism fails○ Operation at temperatures up to 280°C

● Desired state:○ 3D printer head that uses ordinary plastic injection molding pellets as

its feedstock○ Operation at temperatures up to 380°C

● Constraints:○ Cost < $500, preferably $200○ Must be compatible with a majority of hobby grade 3D printers

Additional Deliverables● CAD models of final design(s).● Schematics for electronics.● Bill of Materials with sources of components, quantities and cost.● Clearly illustrated manual that provides instructions on how to build

printhead● Test results demonstrating nozzle is capable of extruding ULTEM high

temperature plastic● Test results demonstrating extruder can run continuously for 10 hours

without clogging or failure

CustomersPrimary Customer: ● Dr. Denis Cormier- Earl W. Brinkman Professor

Secondary Customer: ● 3D printing community: Plans to be made open to the Maker

community under the typical open source non-commercial use terms.

Market Trends● FDM patent expired in 2009, causing an explosion in

the DIY 3D printing market. Since then, the cost of those printers has been reduced by 90%.

● In January 2014, the patent for SLS expired. Nothing of considerable note has been produced yet that is competitive with the current FDM printer prices.

Leading Manufacturers● Stratasys holds the number one

spot with 24.4% of the market share

● Reprap holds 19.2%, while Ultimaker holds 13.3%

● Stratasys was company that originally patented FDM. Their market share is large, but is decreasing as new manufacturers appear

Printer Model Distribution● Makerbot Replicator 2 leads

the models, followed by Ultimaker 1. These are some of the older printers, being manufactured in 2012 and 2011, respectively.

● The Prusa i3 has a surprisingly large distribution, considering it was manufactured in September 2014

Customer RequirementsCustomer Rqmt. #

Importance Description

CR1 9 Uses unmodified plastic injection molding pellets as its feedstock material

CR7 9 Cost should not exceed $500

CR8 9 Documentation in the form of an operation manual required

CR2 7 Must be capable of operating up to 380°C

CR3 7 Must be able to print continuously for 10 hours without failure

CR5 7 Nozzle's overall size and mass must be close to most 3D print head assemblies

CR6 7 Print head must work with standard hobby grade 3D printers

CR9 7 Parts readily available for Hobbyists to re-create the printer head - few specialty made parts

CR4 1 Interchangeable nozzles are required so that different diameter nozzles can be used and clogged nozzles can be removed and cleaned

Engineering Requirements

Benchmarking- 3D Printers

Benchmarking- Single Screw Extrusion

Systems Analysis

House of Quality: CR Analysis

Functional Decomposition

Concept & Architecture Development

Concept Generation

Pugh Evaluation Chart

Selected Concept● Pellet pre-processor● Gravity fed pellets through hopper● Heating by electrical current● Fans for cooling● Screw for driving pellets

System Architecture

Thermal management[Biggest Challenge]

Engineering Analysis NeededHeat Equations

● Conduction: ● Convection:● Radiation: ● Heat due to Friction:

Energy Equations● Energy from motor: ● Energy from heater:● Energy to melt plastic:● Power to drive screw:

Material PropertiesMaterial Density

(g/cc)Electrical, Resistivity (ohm-cm)

Magnetic, Susceptibility (cgs/g)

Specific Heat Capacity (J/g-°C)

Thermal Conductivity (W/m-K)

Melting Point (°C)

Accessibility

Cost Effectiveness

Aluminum* 2.6989 0.0000027 6.00E-07 0.9 210 660.37 readily available

$

Acrylic, Extruded**

1.13-1.19 100e+14-1.00e+15 --- 1.47 0.19 150-249 readily available

$

Arkema Group Plexiglas V052 Acrylic***

1.19 --- --- --- 0.187 230 special order

$$$$$$$

Stainless Steel~ 0.190-9.01 0.00000678-0.000145 1.00-3000 0.200-0.620 2.02-34.3 1230-1530 readily available

$$

Copper, Annealed @20°C~~

8.93 0.0000017 -8.00E+08 0.385 385 1083.2-1083.6 available $$$

Brass~~~ 7.60-8.86 0.00000318-0.0000280 1 0.375-0.380 26.0-233 809-1030 available $$

aluminum oxynitride^

3.696-3.691 ---- ---- 0.781 12.3 1200 special order

$$$$$$$$$$$

Extrusion Screw Research

L/D Ratio:

● 20/1 ratio

Profile: 3 zones- feed, transition, meter

● General purpose use a 10-5-5 profile

Channel Depth:

● Determined by resign to be processed

Helix Angle● The helix angle is the angle of a screw flight relative to a plan perpendicular to the screw plane

Heating Research

Selecting an aluminum heater should be sufficient for the project, although cost and size will be a deciding factor depending on vendor limitations.

Heating Research (cont.)An alternative method to heater bands would be to design some sort of microwave chamber to heat the plastic. This concept was developed by NASA to try and 3D print using Lunar and Mars regolith.

Grinding Pellets Research

Item Name Description Power Cost

KitchenAid BCG111OB Blade Coffee Grinder 160w $29.99

Toastess Model # DLCG559 Blade Coffee Grinder 500w $39.99

Espressione Model # 5198 Conical Burr Coffee Grinder 150w $79.99

Cuisinart Model # DLC-1BCH Blade Food Processor 250w $29.95

Kyocera Model # CM-50 CF Manual Coffee Grinder Manual $47.00

Test Plan OutlineTemperature Verification

Use thermocouples to confirm that the temperature of the heater, melted plastic, and nozzle tip is up to specifications

Power ManagementEnsure that the drive motor, heater(s), and any auxiliary system have enough power to allow the head to operate for the desired run time

Uniform flowDetermine flow rate out of nozzle

Pellet grindingDetermine acceptable grain size for ground pellets to prevent any clogging and find a way to consistently achieve it

Risk Assessment

Risk Assessment Cont.Likelihood Severity

Scale

1 - cause is unlikely to happen

1 - impact on project is very minor, will still meet deliverables on time and within budget

2 - cause could conceivably happen

2 - impact on project is noticeable, will deliver reduced functionality, go over budget or fail to meet req.

3 - cause is very likely to happen

3 - impact of project is severe, will not meet req.

Project Plan (Weeks 3-6)

Project Plan (Weeks 6-9)

Project Plan (Weeks 7-9)

Questions?