The power of speed
High-Velocity Stamping –
an Innovative Technology
AP&T Seminars 2015
About Cell Impact
Cell Impact is a global supplier
to the manufacturing industry of
reliable, integrable and cuttingedge high-velocity units that
result in high-quality production,
greater effectiveness and
capabilities that surpass those of
conventional machine tooling.
The power of speed
How does a fuel cell work?
A
fuel cell stack consists of
patterned plates (separators) and
membranes (MEA).
 Function
of plates:

Gas (H2, NG, etc.) distribution incl.
separation

Water management

Heat transfer

Current transportation

Solid structure
 Function
of membrane: Catalytic
separation into protons (H2 ions)
and electrons
The power of speed
Examples of Fuel Cell Applications
APU
FUEL CELL
VEHICLE
RESIDENTIAL - CHP
STATIONARY
The power of speed
The Challenge apart from Infrastructure
Main challenge today is cost,
and it can be reduced by e.g.:
 Economy
of scale
 Reduction
of precious metals,
e.g. platinum.
 Increased
power density, incl.
improved water management
Focus area in this presentation !
The power of speed
The Power of Speed
The power of speed
Flow Stress of copper as a function
of Strain Rate at strain=0.15
Source: “Dislocation kinetics at
high strain rates”
Source: “High-loading velocity
Tensile Properties and Fracture
Behavior of AC4CH Alloy”
Source: Balanethiram, Ohio
State University “Enhanced
Formability of Sheet Metals at
High Workpiece Velocity”
Source: “High Strain Rate
Deformation Behavior of
Al-Mg Alloys”
Elongation, flow stress, UTS and YS are constant up to a
certain strain rate or velocity, after that it increases rapidly
The Power of Speed
The power of speed
• Elongation are constant up to a certain crosshead
velocity, after that it increases rapidly for particularly FCC
metals.
• Balanethiram calculated the threshold or critical velocity
as:
• It resulted in critical velocities for the onset of inertial
effects at approx. 1-2 m/s. It corresponds well with
achieved results.
Source: Balanethiram, Ohio State University
“Enhanced Formability of Sheet Metals at High
Workpiece Velocity”
What is influencing formability (or elongation)?
Mechanisms / Methods influencing elongation
Plastic
deformation
Microstructure
incl. changes
Temperature
Macrostructural
defects
Pre-straining
Instability in growth of neck
Flow rule
n-coefficient
(strain hardening)
Impurities
Surface defects
Phase transformations
Grain/crystal structure
m-coefficient
(strain rate sensitivity)
Cold work
Cold rolling
Thermal/adiabatic
softening
Slip/slip bands
The power of speed
Particle coarsening
Oxidation
What is mostly influence by stamping speed?
Mechanisms / Methods influencing elongation
Plastic
deformation
Temperature
Microstructure
incl. changes
Thermal/adiabatic
softening
Instability in growth of neck
Flow rule
Slip/slip bands
n-coefficient
(strain hardening)
m-coefficient
(strain rate sensitivity)
Grain/crystal structure
The power of speed
The Power of Speed – Slip Bands/Planes
The power of speed
• Greater number of slip
bands at higher speed
• Microvoids coalesce,
forming a crack, at a
perpendicular direction
at low speed.
• Microvoids have not
sufficient time to join at
high speed. They grow in
a different angled
direction.
SEM at
Low
speed
0.01
m/s
SEM at
High
speed
10 m/s
Source: “High loading velocity Tensile Properties
and Fracture Behavior of AC4CH Alloy”
The Power of Speed – Crystal Structure
The power of speed
FCC metals are showing greatest enhancement in elongation
at higher speeds, due to greater number of slip bands/planes.
FCC metals or alloys with fine grain structure are prone to
enhanced elongation by high-velocity stamping
The Power of Speed – Flow Rule
The power of speed
• The strain hardening
coefficient, n-value, is
showing a threshold when a
certain speed is exceeded.
• The n-value is a good
approximation of the total
elongation (or ductility).
Source: “High Strain Rate Deformation
Behavior of Al-Mg Alloys”
The Stamping and Forming Process
Just before forming starts
V≤20 m/s
Partly formed
V≤15 m/s
The power of speed
Forming just completed
V= 0 m/s
A process similar to conventional stamping. The
main difference is the forming velocity or
speed.
High-velocity Formed Patterns
34 %
38 %
45 %
50 %
52 %
The power of speed
Examples of formed patterns
with Sanergy LT 316L.
Channel forming elongation
increasing from 34 to 52%.
The channel pitch varies
between 0.9 mm to 1.6 mm.
The Process
The power of speed
316L, t=100/(75) µm
Stamping & cutting
7 steps
PVD Coating
Stamping & cutting
3 steps
Laser welding
Cleaning
Drying
Laser welding
Cleaning
Thermal spray
coating
Annealing
Inspection
Source: Austin Power
Engineering 2014
Inspection
Alternative
Process
Typical
Process
Coil Flattening
316L, t=100/(75) µm
Production Line for High-volume Production
• Similar forming technology,
forming plates from thin
sheet metal coil.
• Many lines in operation
world wide, proven
technology
• Fully automated highvolume production
The power of speed
Line Concept for High Volume Production
PVD
Coating
Pre-form and
pre-cut
High-speed
forming
Cutting and
handling
The power of speed
Film Time
The power of speed
Accessibility And Utilization
Accessibility
Incoming material
Operator
Accessibility material feeding
Accessibility forming and cutting presses
Accessibility Automation between presses
Accessibility high velocity press
Accessibility tooling
Accessibility unloading and spot welding
Positioning in process
Total accessibility for planned production
Utilization
Real production speed (no /hours)
Hours planned for production
Possible production / Year
Theoretical max no of strokes / Year
Estimated utilization
The power of speed
99%
95%
98%
95%
95%
95%
98%
95%
98%
72.1%
1,298
8,038
10,431,192
14,688,000
71.0%
Cost Estimation
The power of speed
Assumptions:
o
o
o
o
o
Production cost
Operating
Investment write off: 10 years
Labour
10 million plates per annum
Tooling
Plate size 370 mm x 90 mm
Depreciation
(anode) + 370 x 90 mm (cathode)
Material
= 0,0666 m2
Yield (95%)
Full production speed. Material 316L. Maintenance:
Production location (&cost): Sweden Total per plate:
Total cost per coated bipolar plate assembly,
incl. laser welding is approx. 0.97 €.
0.02
0.09
0.05
0.03
0.56
0.03
0.02
0.81
€
€
€
€
€
€
€
€