Machine Building Article

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Machine Building with
Carbon Graphite Damping Composite
Carbon Graphite Damping Composite is composed of CompoTechʼs Three Dimensional Cellular
Composite, 3Dc, with energy dissipating damping materials included in the composite. Composite Dynamic Damping, cDD.
Three Dimensional Cellular Composite, 3Dc
3Dc is a patented thick composite made up of cells of Graphite
Carbon Fibre surrounded by a cell border of
standard Carbon Fibre.
This material is made into a
beam element, or a tubular
element for a machine.
Diligent design will enable very
little waste with many details made
into the beam at the time of manufacture.
Integrated Composite Connections,
iCC, enable secure connection to metal
components using the ability of composite fibres
to be placed in an advantageous way.
No drilling, min. cutting fibres, fewer manufacturing steps, less waste.
Graphite Carbon Fibre has a very high fibre modulus, up to 900 Gpa.
When this fibre is made into a practical composite a modulus of around
400Gpa can be achieved. When made into a practical beam with steel
elements connected, the combined modulus of 300 - 350 GPa is possible.
The strength of Graphite Carbon Fibre composite is comparable with steel,
but less than conventional carbon fibre.
The graphite carbon composite has a density of 1.5, but a beam with steel
elements may end up at an average density of around 2 which is ¼ that of steel. This fact combined with the higher modulus results in a higher natural frequency.
Steel Section
Comparison of Steel & Composite Beam
260 x 260 mm #
Same dimensions#
260 x 260 mm
834 Kg #
Weight is 64% less#
303 Kg
4.7 x 1013 Nmm2 # EI is 36% more#
6.4 x 1013 Nmm2
562 Hz #
Hz is 140% more#
1354 Hz
Composite
Section
[email protected] #
www CompoTech.com#
CZ Tel. +420 376 521 130
#
Composite Dynamic Damping, cDD
A high natural frequency is beneficial, but the real benefit to machine builders is the improvement in Dynamic Damping. Everything vibrates at itʼs own natural frequency and every material
has a damping coefficient, ζ (zeta) which is the rate of vibration decay.
CompoTech have developed new composites
that have the ability to dissipate vibrational energy.
Tests were done by comparing 3 Spindle Tubes:with and without a simulated tool of 30kg
Steel Spindle Tube
Carbon Fibre Spindle Tube
Natural Frequency = 734Hz
Dynamic Damping, ζ = 0.0025
Natural Frequency = 1401Hz
Dynamic Damping, ζ = 0.003
Steel Spindle Tube
Carbon Fibre Spindle Tube
Natural Frequency = 405Hz
Dynamic Damping, ζ = 0.0025
Natural Frequency = 387Hz
Dynamic Damping, ζ = 0.003
+ 30Kg end mass
Carbon-Graphite-Damping
Spindle Tube
Natural Frequency = 1401Hz
Dynamic Damping, ζ = 0.03
Carbon-Graphite-Damping
Spindle Tube
Natural Frequency = 351Hz
Dynamic Damping, ζ = 0.003
+ 30Kg end mass
+ 30Kg end mass
It was shown that not only do CarbonGraphite-Damping Composites have a
higher stiffness and a higher natural
frequency, but they also have a lower
response at the points of sympathetic
vibration. This reduces the response to
excitation frequencies and should
permit higher accuracy and / or higher
cutting speed. The productivity of
“Removing Metal” should be significantly better.
[email protected] #
7 x better Dynamic Stiffness
Each with the same dimensions, 415 mm x 170 mm, and each tested with the same 4000 N
load. It was shown that the Graphite Carbon Damping Spindle Tube has nearly double the
Natural Frequency, 12 x better Dynamic Damping and 7 x better Dynamic Stiffness.
www CompoTech.com#
CZ Tel. +420 376 521 130
#
Costs and Energy Consumption
This simple spreadsheet shows the relative cost, weight and energy needed to move a beam
with the same stiffness, but made with different materials.
Side of Square Beam
Thickness of Square Beam
Side of Hole in Beam
Length of Beam
Density
Mass of Beam
Price / Kg
Price of Beam
mm
mm
mm
Kg/m3
Kg
€/kg
€
Carbon Graphite
Composite
300 mm
7.35 mm
285 mm
6m
1,400 Kg/m^3
72 Kg
120 €/Kg
8,673 €
2nd Mom.of Inertia
E Modulus
mm4
GPa
1.23E+08 mm^4
300 KN/mm^2
Make the Stiffness the same
KNmm2 3.69E+10 KNmm^2 3.69E+10 KNmm^2 3.67E+10 KNmm^2
Equipment Load on Beam
Kg
60 Kg
Average Acceleration
m/s2
2.5 M/s^2
Length of bed
m
7m
Time to 1/4 cycle
s
1.18 sec
Time for complete Cycle
s
4.73 sec
Peak Velocity
m/s
2.96 m/s
Force to accel. & decel.
Kgm/s2
331 N
Energy (Work) for 1 cycle
Kgm2/s2
4,630 Nm
System efficiency
65%
Cycles per day
6,085
Energy per Day
12 kWh
Energy per Year
3,010 kWh
Energy greater than Carbon Composite
Energy Cost per Year
451 €
Carbon Composite Saving per year
Pay Back on energy
Power Required......
Kgm2/s3
1.5 kW
Estimated cost of drive system
3,500 €
Years to pay off difference in cost of Carbon Composite...>>>
Joule / kWh
3600000
€/kWh
0.15
Steel
300 mm
10.90 mm
278 mm
6m
7,850 Kg/m^3
594 Kg
4 €/Kg
2,375 €
Concrete
300 mm
100.00 mm
100 mm
6m
2,620 Kg/m^3
1,258 Kg
3 €/Kg
3,773 €
1.76E+08 mm^4
210 KN/mm^2
6.67E+08 mm^4
55 KN/mm^2
60 Kg
2.5 M/s^2
7m
1.18 sec
4.73 sec
2.96 m/s
1,634 N
22,879 Nm
65%
6,085
59 kWh
14,874 kWh
5 x
2,231 €
1,780 €
3.54 Yrs
7.4 kW
5,500 €
2.42 Yrs
Hrs / day
8
60 Kg
2.5 M/s^2
7m
1.18 sec
4.73 sec
2.96 m/s
3,294 N
46,116 Nm
65%
6,085
120 kWh
29,981 kWh
10 x
4,497 €
4,046 €
1.21 Yrs
15 kW
9,300 €
-0.22 Yrs
Days / Year
250
The capital out lay for the drive system is cheaper for the Carbon Graphite. It is already more
economic than concrete. Other capital cost must also be proportionately cheaper. Compared to
Steel and for the same stiffness; Carbon Graphite is 1/8 of the weight and 1/5 of the power requirement. The "knock on" effect only has to save €4,000 to make it cheaper to purchase.
Even without less capital outlay, the annual saving makes it a worthwhile investment. Machines with more moving beams would make proportionately more savings.
The Dynamic Stiffness will be factor of 7 better so the extra productivity should also be included
in the return on investment calculation.
[email protected] #
www CompoTech.com#
CZ Tel. +420 376 521 130
#
Integrated Composite Connections
Why drill holes when they can be made in the process of manufacturing the beam?
CompoTech have developed the idea of “Winding Holes” and have researched the stresses
around these holes.
[email protected] #
www CompoTech.com#
CZ Tel. +420 376 521 130
#
Comparing Steel with Carbon Graphite Damping Composite
Over 1.5 x the stiffness...
About 1/4 of the weight...
Over 2 x the natural frequency...
Possibly 12 x the Dynamic Damping...
Possibly 7 x the Dynamic Stiffness...
Potentially significant productivity improvements...
Less operational energy consumption...
Comparative cost with diligent design…
About CompoTech
CompoTech is a Composite Engineering Company and Design Consultancy
with expertise in Technically Advanced Composite Tubes
CompoTech Design and Manufacture Structural Composite beams and tubes,
and are specialists in…
Innovation of structure
Innovation of composite
Innovation of manufacturing process.
CompoTech have an expanding portfolio of new technology, including…
Three Dimensional Cellular Composite#
3Dc
Composite Dynamic Damping#
cDD
Integrated Composite Connections#
iCC
...and there is more to come.
CompoTech will continue to expand and lead in this area of technology.
[email protected] #
www CompoTech.com#
CZ Tel. +420 376 521 130