Transcript Project Update April 24, 2003 Rachel Sharp Corinne Packard

Project Update
April 24, 2003
Massachusetts Institute of Technology
3.082
Rachel Sharp
Corinne Packard
Isaac Feitler
Hao Hu
This Week’s News
 Die fabrication
 Troubleshooting the Magneform machine
 New, thinner workpieces
 Contingency plans
Review of Goals
 Conduct electrohydraulic forming of sheet
metal.
 Form sheet metal ‘part’
Revised Gantt Chart
Week
1
2
3
4
5
6
7
8
9
10
11
12
13
14
Vessel design and parts acquisition
Break
Capacitor bank acquisition
CAD
Pressure Vessel assembly
Die printing
Casting of mold
Electrohydraulic test
Funnel formation
Final part formation
Presentation preparation
Pressure Vessel
Capacitor Bank
Mold
Electrohydraulic forming
Final Presentation
Creating the Dies
 CAD files of dies created with Solidworks
 Dies are printed 3D printer
 From MIT & Z-corp
 Prints composed of starch
 Creation of Plaster Mold
 Casting with Bronze
LOST WAX CASTING
3D print infiltrated with liquid wax in ZW4
Remaining crevices in print sealed by hand
with scrap wax and smear on sealant wax
Pegs and blocks of Hex wax and bees wax
are mounted on top of the the 3D print with
sticky wax to form funnels and air holes
All edges are smoothed and all gaps
remaining are sealed to prevent ceramic
mix from entering
Lost Wax Casting, cont’
Preparing ceramic mold mix
Ceramic powder – 6 liters
– ceramic C-5, bauxite and fused silica
Binder Mix – 25 % weight total of powder
– R25 ethyl silicate, 60% weight total
– Straight alcohol, 40% weight total
– Ammonium Carbonate catalyst, 6% weight total
* over 100% weight, ammonium carbonate acts to
catalyze reactions, doesn’t affect the composition of
final product, amount present miniscule
Lost Wax Casting, cont’
Burn out starch and wax at Boxford, MA
Pour in liquid bronze
Post Processing
– smooth out all edges with milling tools
– Face off the top and bottom sides of the die in
a lathe to ensure proper clamping
Recent Magneform History
 Wednesday (last week):
 Small capacitor bank option abandoned
 Broken safety interlock on Magneform discovered and
replaced with a jumper.
 Magneform fired on empty soda cans.
 Magneform works, but not perfectly.
 Thursday (last week):
 Examination of Magneform continues, safety
concerns raised and discussed.
 New plan: run the electrohydraulic forming in Parallel
with the Magneform to help prevent malfunction.
 Monitor current to electrohydraulic system with
special current monitor.
Recent Magneform History, continued.
 Friday (last week):
 Magneform behaves strangely in further tests,
charging but failing to discharge as expected.
 Different discharging events produced disturbingly
loud noises.
 No major components appear damaged.
 Tuesday:
 Friday’s problems traced to burnt out resistor.
 Replacing the resistor restores the Magneform to it’s
previous state of working imperfectly.
 Wednesday:
 Further probing and tracing.
 Options for using and repairing Magneform
considered.
Notes on Troubleshooting
 Dave Bono’s experience helps.
 Circuit schematics are essential to
understanding the machine and knowing
which components to test.
 Voltages and resistances measured with
multimeter to check proper function and
identify malfunctions
Troubleshooting Precautions
 Care must be observed when probing the
machine:
 Machine only plugged in when necessary
 Use probes, clips to touch machine, avoid
contact with skin.
 Avoid dropping small parts into the machine,
be prepared to catch screws that you remove.
 When possible, use only one hand to reach
inside machine, to avoid a conducting path
across your heart.
Current Magneform Status
 Our understanding of the Magneform is
becoming more sophisticated.
 Magneform is partially malfunctioning, but can
be made to work safely (at least for the
operators, if not the machine)
 Inspections continue, to figure out the best way
to make the machine work.
 The Magneform may break permanently at
some point, so we will minimize any firing of the
Magneform that isn’t intended to perform
electrohydraulic forming.
New Workpieces
 The portion of energy that will flow through our
system, in parallel with the Magneform work coil,
is currently unknown.
 We’ve purchased thinner workpiece materials to
increase the likelihood of significant results:
 5052 Aluminum in thicknesses of 0.032, 0.040, and
0.050” (old workpieces 0.0625” thick)
 Also, 110 Copper Alloy in thicknesses of 0.021 and
0.032”
What’s next?
 Electrohydraulic tests with the Magneform,
free expansion without a die.
 Workpieces marked with spraypainted
grids, so that we can measure strains.
 Casting and processing dies.
 Final part formation.
Contingencies
 One option was to ship our pressure vessel to
Prof. Daehn at Ohio State University, but we’ve
run out of time for that.
 Although the Magneform is not working perfectly,
the major, high-power compenents all seem fine,
so we’ll be able to use it.
 If most of the energy goes into the work coil,
instead of our system, we may be able to build
our own coil with greater impedance.
Acknowledgements
 Dave Bono for help troubleshooting the
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Magneform
Chris Schuh, Joe Parse, and Yet-Ming Chiang
for general advice.
Toby Bashaw for all the help making the parts of
our system.
Yin-Lin Xie and Maria Nargi for help purchasing
parts and materials.
Print3 and especially Flex for putting up with our
sometimes disruptive work.