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Team Members: Katie Kaser - Introduction & Concept Generation

Moshe Solomon - Concept Selection

Joanna Pirnot - Concept Development

Lihong Xu - Budget

Sponsor: Fraunhofer USAAdvisor: Dr. Michael Keefe

TEAM 11

ULTRASONIC MIXER

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METAL POWDER

POLYMER

INJECTION MOLDING

MIXING

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Mechanical Mixers

• Size

• Cost

• Wear

• Contamination

• Maintenance

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MissionDesign a non-mechanical mixer for homogenizing powder injection molding feedstock by April 1999

Approach: Identify wants and constraints Benchmark previous technology Generate set of concepts Select best concept Execute design via best engineering methodology

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Customers

Sponsor - Fraunhofer Mixer suppliers

Misonix Inc. Ultrasonic consulting companies

Advanced Sonic Processing Systems Anyone involved in powder injection molding

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Wants & Constraints

Top 5 Wants Temperature Control Low Contamination Level Ease of cleaning Cost Produce measurable

quantity

Constraints Completion by

April 1999 Produce

homogenous mixture

Safety

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System Benchmarking

Mechanical Mixers High Shear Mixers

Static mixer Pump/internal obstacle mixer

(Sonolater) Ultrasonic Mixers

Probe-type External sound source

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Metrics Want

Temperature control

Low contamination level

Handle variety of materials

Metric

Temperature control range

Percentage contaminants

Viscosity range

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Functional & Ultrasonic Benchmarking

Functions Feeding Heating Mixing Cooling

Ultrasonics Ultrasonic Generators Transducers

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What did we learn?

Ultrasonics is a significant source of heat

Heating and mixing should be as concurrent as possible

A system incorporating a probe is subject to contamination and

wear on the probe

More energy reaches the material to be mixed using a probe

than transmitting through walls of a vessel

Ultrasonics are capable of mixing solid powders in a polymer

resin.

On the macroscopic level a homogenous mixture was

achieved

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Target Values Metric

Temperature control range

Volume loading metal powder

Ease of cleaning

Target Value

0 to 200 degrees C

60%

Time to Disassemble

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Critical Functions

Feeding Heating Mixing Cooling/Removal

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Concept Generation Rotating Mixer Opposing Sound Sources Probe-type ultrasonic mixer Separate heating/mixing chamber Hexagonal tube mixer

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Concept 3: Rotating Mixer

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High Intensity Ultrasonic Processor

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CONCEPT SELECTIONS S D R E S U L T S CONCEPTS

WANTS METRICS TARGET VALUES 1 2 3 4 5

SUITABLETEMPERATURE

AVOID CONTAMINATIONDUE TO ABRASION

AVOID CONTAMINATIONDUE TO AN EXTERNAL

SOURCE

EASY TO CLEAN

VARIETY OF MATERIALS

REASONABLE COST

PRODUCE A MEASURABLE

QUANTITY OF MATERIAL

REPEATABLE PERFORMANCE

PRODUCE FEEDSTOCK IN USABLE FORM

AVOID WASTE MATERIALWHEN CLEANING

CONTROLED FEEDINGMECHANISM

TEMPERATURE OF THE MATERIAL BEING MIXED

% CONTAMINANTS IN THE PRODUCT

% CONTAMINANTS INTHE PRODUCTS

ABILITY TO DISASSEMBLE,CLEAN BY HAND, &

KEEP WARM WHILE CLEANING

VISCOSITY

COST MUCH LESS THAN A MECHANICAL MIXER

OUTPUT / HOUR

RELIABILITY

GEOMETRY OF THEPRODUCT

% OF MATERIAL LOST

% OF MATERIAL LOST

0 TO 200 DEGREES CELSIUS

LESS THAN 3%

LESS THAN 3%

0 TO 100 DEGREESCELSIUS

0 - 1000 Pa-s

LESS THAN $5000

GEATER THAN OREQUAL TO 5 LBS/HR

LOW STANDARDDEVIATION IN MIXING

RESULTS

PELLET OR SPHERICALSHAPE

LESS THAN 5%

0%

1

5

2

555

5

5

2

4

5

5

5

4

3

4

344

2

1

3

4

2

3

3

4

4

4

344

2

1

3

4

3

4

3

4

3

4

234

2

1

2

4

2

3

3

5

4

4

344

2

1

5

4

5

4

4

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Concept SelectionEvaluation of Wants (Scale 1-5, 5 being the highest score)

1st (probe type mixer) - 54 pts 2nd (opposing sound sources) - 40 pts 3rd (rotating mixer) - 43 pts 4th (separate heating and mixing) - 37 pts 5th (hexagonal tube mixer) - 49 pts

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CONCEPT SELECTIONCRITICAL

FUNCTIONS

FEEDING

Automatic Feeder Unit Trough

HEATING

Double Walled Vessel with Inlet and Outlet for Water Circulation

Heat Exchanger Fluid Pumping System

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CONCEPT SELECTIONCRITICAL

FUNCTIONS

MIXING

600 Watt Ultrasonic Probe Booster Horn

REMOVAL / COOLING

Teflon Stopcock Conveyor Belt Collecting Pan

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Concept Development

Demonstration (Video)

Test Results Critical Functions Prototype vs. Target Values

Modifications/Suggestions

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Feeding

Capabilities

Automated feeder sufficiently transports powder to the mixing vessel

Limitations

speed of feeder

Residual amount of material remains on the surface of the funnel and feeder tubing

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Heating Capabilities

sufficiently melts materials with a low melting point

ex. Paraffin

sufficiently removes excess heat produced by ultrasonic processor

sufficiently keeps materials warm during removal

Limitations

the variety of materials (with a high melting pt.)

ex. Polypropylene

temperature range 0 to 100 degrees Celsius

due to probe limitations

the heating fluid (water) is incapable of temp. higher than 100 degrees Celsius

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Mixing Capabilities

Solids Loading Original Design

• 20% solids loading Shape of the vessel

• 35% solids loading Shape of vessel and Booster Horn

• 60% solids loading

Product Satisfactory homogeneity

• microscope examination

• melting (consistency)

• capillary rheometer

No degradation of polymer of deposits of powder

Limitations Volume no greater

than 50ml splashing occurs

Amplitude of the Horn must be 65%

splashing occurs

Variety of materials only soft materials,

otherwise erosion of the tip occurs

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Removal of Material Capabilities

regulating flow of the material

flick valve

material is removed within 2 minutes

no excess heat is required

96% of material is recovered

prior to cleaning

Limitations

If the flow is too slow, material tends to solidify prior to exiting the vessel

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Cooling Capabilities

material does not solidify prior to contact with the conveyor belt

Air cooling is a sufficient method of cooling feedstock

the material is in a usable form

Limitations

conveyor belt must be set horizontally

material flows too quickly

speed of conveyor belt must be on the lowest setting

material not cooled upon reaching the end of the conveyor belt

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Metrics Target Values Prototype Test Results

1 temp. of the materials 0 to 200 degrees Celsius

0 to 100 degrees Celsius

2 % contaminants in the product

no visual change in color soft materials - no visual change in color

hard materials - visual change in color (white to gray)

3 ability to disassemble 5 minutes 5 minutes

ability to clean by hand less than 30 min 5-10 minutes

ability to keep material warm while cleaning

0 to 100 degrees Celsius

no extra heat was required during the cleaning of the vessel

4 viscosity volume loading 60% volume loading 60%

5 cost significantly less than a mechanical mixer

less than $5,000 $521

6 Output/hour 5 lbs/hr < 4 lbs/hr7 reliability low standard deviation uniform color and consistency8 geometry of the product pellet or spherical shape pellet shape

9 % of material lost in removal

Less than 5% less than 4% of material lost

10 % of material lost during feeding

0% 3%

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Modifications/Suggestions(addressing our limitations)

Feeding use spherical shaped powders

Heating purchase an air cooling converter

allows probe to safely reach higher temperatures

use a fluid capable of reaching a higher temperature

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Modifications/Suggestions Mixing

purchase a larger vessel to increase the output/hour (no greater than 250ml batches - probe tip (1/2 diameter)

purchase a larger probe tip - 1in diameter (capable of mixing volumes up to 1000ml)

coat the tip of the probe with tungsten carbide this will reduce the erosion of the titanium tip

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Removal

Apply heat to the nozzle area to eliminate faster cooling of material; use heating gun

Cooling

Use longer conveyer belt; current length insufficient for air-cooling of larger pelleted feedstock

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Load vs. Time (Velocity = 1mm/min)

0

5

10

15

20

25

30

35

0.234 0.2345 0.235 0.2355 0.236 0.2365 0.237 0.2375 0.238 0.2385 0.239 0.2395

Time (sec)

Load (N)

Averag e load = 21.06 N

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Force vs. Time (Velocity = 80mm/min)

0

5

10

15

20

25

0 2 4 6 8 10 12

Time (s)

Force (N)Average Force = 19.10 (N)

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Budget

All Budgeted Material and Equipment Expenditures

Estimated Upgrade Cost

Engineering Development Time

Conclusion

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Description Manufacture Cost ($)Fabrication

hours

*Metering feeder (include funnel) HAAKE 4000.00Feeding tube Custom made 2.49 2Ultrasonic mixer Cole-Parmer 4000.00Booster horn Cole-Parmer 350.00Mixing vessel Custom made 168.50 6Vessel holder Custom made 6

* Heat exchanger HAAKE 5000.00* Conveyer HAAKE 2000.00

Total cost (excludes items for mechanical mixer) 4520.99

Projected Production Cost: $15520.99Total cost for the project: $520.99

All Budgeted Material

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Estimated Upgrade Cost

Description Cost ($)Bigger Tip 450.00Air converter 1100.00

Larger vessel 200.00

Tungsten carbide coating 400.00

Total upgrade cost: $6670.99

$50K to $70K

$6700

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Engineering Development Time

Fall10 hr/person/week for 13 weeks

Winter4 hr/person/week for 4 weeks

Spring12 hr/person/week for 10 weeks (include testing time 4hr/person/week for 6 weeks)

Total time: 1064 hours

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In Conclusion

. . . A great team gained experiencefrom the opportunity to use engineering theory in a practical way, developingan innovative technology solutionmeeting the specific real-world wants of our industrial customer. . .