Ultrasonic Mixer
Project 99.11
Design Team Members:
Katie Kaser
katie@udel.edu 731-7638
University Gardens Apartments Newark, DE
Lihong Xu
arthur@udel.edu
239-4768
Joanna Pirnot 90620@udel.edu 366-7473
Moshe Solomon moshe@udel.edu 455-1246
Sponsor:
Don Kupp
kupp@frc-de.fraunhofer.com 369-6757
Background
Injection molding is an increasingly common manufacturing process, used to
produce metal, plastic, and ceramic parts for many applications in medical,
biotechnology, automobile, and aerospace industries among others. Plastic injection
molding involves melting the thermoplastic material, forcing the molten plastic into a
mold cavity, and cooling it to a solid shape. Fine detail and precision are possible, but the
quality of the final product is dependent on the quality of the feedstock used to produce
it. The PIM (powder injection molding) feedstock that Fraunhofer uses is a metal or
ceramic powder in a polymer matrix. It must be a homogeneous mixture, and its
homogeneity is determined by the quality of the mixing and compounding steps that
disperse the powder into the melted polymer. The next step in processing is to
chemically remove all of the polymer from the molded piece, leaving a solid metal part.
Currently, the technology used to create the PIM feedstock is a complex mechanical
mixer.
Problem Statement
Traditional mechanical mixers have a number of drawbacks. Because of the
complexity of the problem – the necessity of melting the polymer, mixing in the metal
powder with mixing screws, carefully controlling temperature and composition of the
mixture – mechanical mixers are often large and expensive. The abrasive nature of the
metal powder causes wear on the mechanical parts, and as the mixer components wear
away, the feedstock can be contaminated. The PIM feedstock is also highly viscous,
requiring the mechanical mixer to use a lot of energy. If the mechanical energy source is
replaced with an ultrasonic energy source, similar mixing results should be achievable,
however certain drawbacks of the mechanical mixer will be eliminated.
Ultrasonic mixers are already in use for a variety of applications, including
biological research. However, the existing ultrasonic mixers are used for much lower
viscosity liquids. Many existing ultrasonic equipment can only handle temperatures up to
150C. Therefore it is necessary to design a new mixing system to deal with the PIM
feedstocks. An ultrasonic mixer offers non-mechanical means to create homogenous
mixtures of fine powders in a polymer melt, for polymer systems with less than 200C
degrees melting temperatures.
A non-mechanical mixing device would have several advantages over the existing
mixers. Less wear from abrasion should occur, since there would be no mixing
components directly in contact with the powder/polymer mix. The difficulty of mixing
would be lessened by the use of a high-energy ultrasonic source. Also, the need to
elevate the temperature could be assisted by the ultrasonic waves, so reducing the
external heat application should be possible. Cleaning of the mixing chamber would also
be easy compared to the cleaning of the complex mechanical mixer. A successful nonmechanical mixer would benefit any lab or industry carrying out powder injection
molding.
Mission
Our mission is to design a system incorporating a suitable non-mechanical device
for homogenizing powder injection molding feedstocks into relatively high viscosity
liquids, by April 1999. We will be using the engineering method, collecting wants and
constraints, and selecting the best concept to fulfill our mission.
Customers
Our primary customer is our sponsor, Fraunhofer, and the company representative we are
contacting is Don Kupp. Their wants and constraints are the most important to satisfy,
because the satisfaction of the user at Fraunhofer will determine the future use of the
design. Also, as they only require lab scale equipment, their wants will be easier to
satisfy with an initial prototype than the wants of our industry customers. Many of
Fraunhofer’s wants and constraints have already been established.
Wants:
1. Produce a measurable quantity of material

Metric: Greater than 100 grams/hour
2. Suitable temperature control
3. Easy to clean equipment

Disassembly possible and easy
4. Have a system which can handle a variety of materials

Metric: handle a range of viscosity up to 1000 Pa*s
5. Avoid excessive cost
6. Durable equipment
7. Sensor for viscosity and temperature
8. Method to feed material into device
9. Have reliable performance

Repeatable results
10. Easy to use system
Constraints:
1. Completion of design project by April 1999
2. Produce a homogenous mixture of powder injection molding feedstock
3. Produce material in a usable form
Our other customers include companies which sell or manufacture ultrasonic mixing
devices; among these, Advanced Sonic Processing Systems (David Hunicke), Berliner
Ultrasonic Processing (Mr. Berliner), Sonic Corporation (Claire Skidd), and Nirvanatron
Ultrasonics (D. Ciervo). Other customers would include people who would actually be
operating the equipment, such as lab technicians. These people’s wants and constraints
will also help determine our focus in the project. (See Appendix 5 for SSD sheet)
Wants:
1. Ease of use (controls)

On/off switch, feedback mechanisms, automatic temperature/frequency
adjustment
2. Easy to clean and maintain

Disassembly possible
3. Temperature control
4. Longevity of mixer
5. Ability to handle highly viscous materials
Constraint:
1. Sealed and electrically safe product

Metric: NEMA (National Electronics Manufacturing Association) rating
of 4 or higher

Meet NEC (National Electrical Code) standards
Benchmarking
Given the problem statement, and some wants and constraints, we decided that
there were three areas we needed to benchmark.
1. Mechanical mixers, because they successfully produce a homogenous mixture
2. Ultrasonic mixers, because they are non-mechanical and fulfill many of our
other wants
3. Metal powders, because their properties are of concern in the mixing process
In the first of these three areas, we found a number of companies that are major suppliers
of mechanical mixing devices: D-Tex, POMINI, and Leistritz. These mixers operate by
extruding the feedstock through co-rotating or counter rotating screws. The mixing time
is variable, feeding mechanisms are included, and the material can be extruded into the
desired shape. Many mechanical mixers have features that match some of our other
customer wants, such as thermal sensors, automatic frequency and amplitude controls,
and safeties against overload or overheating. We may be able to incorporate some of their
same controls into our design for a non-mechanical mixer, therefore we will continue to
look at them. See Appendix 1.
Ultrasonic mixers on the market are available in several forms. We obtained a list
of 16 companies that specialize in ultrasonics in order to begin our benchmarking. See
Appendix 2. One type of mixer involves placing an acoustical tool, known as a probe or
horn, into the solution you want to mix. The electrical energy from your power supply is
transmitted to the transducer, where it is changed into mechanical vibrations. The probe,
creating pressure waves within the solution, intensifies these vibrations. Millions of
microscopic bubbles are formed; they expand during the negative pressure excursion and
collapse during the positive pressure excursion. This is referred to as cavitation, and the
intensity of the cavitation depends on the amplitude of the probe and the properties of the
medium.
Another type of ultrasonic mixer has a closed chamber that the material is fed
into. Opposing diaphragm plates and transducers surrounds the chamber. The liquid in
contact with the diaphragm plate or sound source is cavitated as described above, and
activating the opposing diaphragm plates intensifies the acoustic pressure wave.
Implosive forces are created within the processing chamber, which facilitates the mixing.
See Appendix 3. Information about metal powders is in Appendix 4.
Budget
The sponsor has indicated that the budget is not a concern in the design of this
project. A meeting, with our sponsor, has been made for the afternoon of 9/23/98 to
establish some financial guidelines.
Conclusion
Our schedule up until this point has dealt with benchmarking products and
gathering wants and constraints, to provide useful information about existing equipment
that could relate to our purpose. From this point, we will be looking into specific
elements that could meet our established wants and requirements, as well as starting our
calculations to determine what our power needs are. Our continued research on
mechanical and ultrasonic mixers will help us better define our wants and constraints.
Our schedule up until the progress review, Oct. 28, 1998, is attached at the end of this
report. We will be talking to our sponsor, and considering recommendations of people in
industry, to determine if certain existing components can be incorporated into our project.
GROUP 11 CODE OF COOPERATION
1.
Everyone should participate equally
2.
Everyone should agree on meeting times
3.
Be flexible about meeting times
4.
Everyone attend all meetings
5.
Attend all meetings on time
6.
Be prepared for meetings
7.
Be respectful of each other and each other’s ideas
8.
Ask questions if you don’t understand something
9.
Help each other when needed
10.
Distribute tasks according to people’s strengths
11.
Keep other people informed of your work
12.
Share responsibility
Schedule
ID
1
Task Name
Duration
First meeting with customer
0.06 days
Thu 9/17/98
Start
Thu 9/17/98
Finish
T
2
define project
0.06 days
Thu 9/17/98
Thu 9/17/98
1
3
collected list of wants and constraints
0.06 days
Thu 9/17/98
Thu 9/17/98
1
4
saw existing equipment
0.03 days
Thu 9/17/98
Thu 9/17/98
1
5
introduced to the process of making PIM feedstock and the materials used in the
feedstock
0.03 days
Thu 9/17/98
Thu 9/17/98
1
3.19 days
Mon 9/14/98
Thu 9/17/98
3.19 days
Mon 9/14/98
Thu 9/17/98
0.5 days
Mon 9/14/98
Mon 9/14/98
0.19 days
Thu 9/17/98
Thu 9/17/98
6
7
benchmarking
contact manufacturers
8
ultrasonic
9
mechanical mixers
10
contact consultants of ultrasonic processing
0.25 days
Mon 9/14/98
Mon 9/14/98
11
contact people in industry or research that would use an ultrasonic
mixer
0.13 days
Mon 9/14/98
Mon 9/14/98
0.88 days
Tue 9/22/98
Tue 9/22/98
12
written proposal
13
oral proposal
1 day
Thu 9/24/98
Thu 9/24/98
14
meet with customer
1 day
Thu 10/8/98
Thu 10/8/98
15
clarify wants and constraints
1 day
Thu 10/8/98
Thu 10/8/98
16
view present ultrasonic mixer
1 day
Thu 10/8/98
Thu 10/8/98
1 day
Thu 10/8/98
Thu 10/8/98
1 day
Tue 9/22/98
Tue 9/22/98
21 days
Thu 9/24/98
Thu 10/22/98
17
18
obtain access to laboratory equipment and
computers
Establish metrics for wants and constraints
19
Brainstorm
20
address whether the process is batch or continuous
21 days
Thu 9/24/98
Thu 10/22/98
21
address energy requirements
21 days
Thu 9/24/98
Thu 10/22/98
22
21 days
Thu 9/24/98
Thu 10/22/98
21 days
Thu 9/24/98
Thu 10/22/98
24
research ultrasonic equipment: probes, transducers,
etc…
determine whether the equipment is mobale or
stationary
address contamination issues
21 days
Thu 9/24/98
Thu 10/22/98
25
address maintenance issues
21 days
Thu 9/24/98
Thu 10/22/98
26
determine required sensors: temperature, frequency and amplitude of sound waves, watt meter,
viscosity
determine production
volume
21 days
Thu 9/24/98
Thu 10/22/98
21 days
Thu 9/24/98
Thu 10/22/98
23
27
28
Progress Review
1 day
Wed 10/28/98 Wed 10/28/98
1
Customer Data and Wants Formulation
Project Title: Ultrasonic Mixer
Mission
Statement:
Design a system incorporating a suitable non-mechanical device for homogenizing powder injection molding feedstocks into relatively high
viscosity liquids.
Customer Information
Name
Organization
Want
Information
10
Rank
0.45
1st Want
0.25
2nd Want
Priority
0.15
3rd Want
Don Kupp
Fraunhofer
1
Produces a
Will be suitable for a Temperature control
homogenous mixture variety of materials
and viscosities
David Hunicke
Advanced Sonic Processing Systems
2
Long Life
Sealed and
Electrically Safe
Tim Weaver
Penn State University
3
Ability to handle
highly viscous
materials
Temperature control Consistent
Performance
Dr. Karl Frank
Hens
Thermat: President and CEO
4
Mr. Berliner
Berliner Ultrasonic Processing
5
Claire C. Skidd
Sonic Corporation
D. Ciervo
Nirvanatron Ultrasonics
Miriam Blednick
The Virtis Company
Dennis Atallian
General Motors
Dr. Majidi
UD Material Science Department
Produces a
Durability: must
homogenous mixture account for the fact
that the radiating
face erodes fairly
rapidly
Controls: on/off,
wattmeter, feedback
mechanism/sensor
Ability to use a wide
variety of materials
0.1
4th Want
Repeatability
0.05
5th Want
Quantity of product:
small
Easy to clean and maintain
Continuous Processing
From an external
Ultrasonic source
Temperature
control