1. business and industrial
2. chemicals industry
3. plastics and polymers

SPECIALTY TESTING & DEVELOPMENT COMPANY, INC.
A NEW DESIGN FOR SPIRAL CONTRACTOMETERS
A NEW DESIGN FOR SPIRAL CONTRACTOMETERS
A NEW
SPIRAL
CONTRACTOMETERS
KNOW
THE DESIGN
STRESS FOR
IN YOUR
APPLIED
METALLIC COATINGS
KNOW
KNOW THE
THE STRESS
STRESS IN
IN YOUR
YOUR APPLIED
APPLIED METALLIC
METALLIC COATINGS
COATINGS
ADVANTAGES
ADVANTAGES
IMPROVEMENTS
IMPROVEMENTS
Guess work
is eliminated
ADVANTAGES
Guess work is eliminated
Perfect
centering
of the spiral
• Guesscentering
work is eliminated
Perfect
of the spiral
Surface
area
is same
spirals
•
Perfect
centering
of for
theall
spiral
Surface area is same
for
all
spirals
Shorter
test
times
500
µʺ
deposit
• Shorter
testtimes
times- -500
500µʺ
µꞌꞌdeposit
Shorter
test
deposit
Holes
at
spiral
ends
so
no
• Holes at spiral ends so noslippage
slippage
Holes at spiral ends so no slippage
Lab
totolab
work
• Lab
lab
workmore
moreconsistent
consistent
Lab to lab work more consistent
• Accurateand
andrepeatable
repeatableresults
results
Accurate
Accurate and repeatable results
• Simple
andrapid
rapidcalculations
calculations
Simple
and
Simple and rapid calculations
TeflonIMPROVEMENTS
inserts reduce friction
Teflon inserts reduce friction
Interior
spiral reduce
surface is shielded
• Interior
Teflon inserts
spiral surfacefriction
is shielded
inserts
prevent
thread
stripping
• SS
Interior
spiral
surface
is
shielded
SS inserts prevent thread
stripping
Teflon
pins
replace
wheels
that bind
• Teflon
SS inserts
stripping
pinsprevent
replacethread
wheels
that bind
pins replace
bigthat
screws
• Calibration
Teflon pins replace
wheels
bind
Calibration pins replace big screws
deposit
on inside
• Minimal
Calibration
pins replace
big surface
screws
Minimal deposit on inside surface
• 30%
Minimal
on inside
surface
glassdeposit
filled nylon
construction
30% glass filled nylon construction
• More
30% glass
filled
nylon
construction
precise
scale
to arrow
view
More
precise
scale
to
arrow
view
• More precise scale to arrow view
1
1
SPIRAL CONTRACTOR MEASUREMENT METHOD AND CALCULATIONS TO
SPIRAL
CONTRACTOR
AND
CALCULATIONS
TO
DETERMINE
INTERNAL MEASUREMENT
DEPOSIT STRESSMETHOD
IN APPLIED
METALLIC
COATINGS
DETERMINE INTERNAL DEPOSIT STRESS IN APPLIED METALLIC COATINGS
Internal stress exists as an inherent force within electroplated and chemically applied metallic deposits.
Internal
stress
as anorinherent
force in
within
electroplated
chemically
applied
metallicindeposits.
This induced
stress
can exists
be tensile
compressive
nature,
causing theand
deposit
to contract
or expand
relation to
Thisbase
induced
stressHigh
can be
tensile
or compressive
nature, micro-cracking
causing the deposit
contract or expand
in severe
relationcases
to
the
material.
levels
of stress
in depositsinproduce
and to
macro-cracking,
and in
the
base amaterial.
High levels
of stress
deposits
produce micro-cracking
and macro-cracking,
andwave-like
in severe cases
produce
lack of deposit
adhesion
in theinform
of blistering,
peeling, and flaking.
In extreme cases,
produce
lack of deposit
adhesion in
the formand
of blistering,
peeling,
In extreme cases, wave-like
ripples ina electroforms,
accelerated
corrosion
deposit wear
failureand
canflaking.
also occur.
ripples inThe
electroforms,
accelerated
corrosion
deposit
wear failure
also occur.
two primary
ways to evaluate
theand
internal
deposit
stress incan
metallic
coatings that are experiencing use
The
ways
to evaluate
the internal
deposit
stressContractometer
in metallic coatings
that are
experiencing
use
worldwide
aretwo
theprimary
bent strip
Deposit
Stress Analyzer
and
the Spiral
methods.
These
represent the
worldwide
are
the
bent
strip
Deposit
Stress
Analyzer
and
the
Spiral
Contractometer
methods.
These
represent
the
only two stress test procedures that have approval status by the American Society for Testing Metals Standards.
only
twoother
stressmethods
test procedures
that
have
by the
Testingpractice.
Metals Standards.
Several
have been
used
in approval
the past, status
but these
haveAmerican
not been Society
put intofor
common
The Stress
Several
other
methods
have
been
used
in
the
past,
but
these
have
not
been
put
into
common
practice.
The Stress
Meter makes use of a disk that bows inward or outward as deposition commences depending on the nature
of the
Meter
makes
use of
a disk that
inward
or outward
deposition
dependingAnother
on the nature
of the
stressed
deposit.
Accuracy
andbows
stripping
metallic
layersas
from
the diskcommences
remain problematic.
method
stressed
Accuracy
and stripping
metallic layers
from
disk remain
Another
method
measuresdeposit.
the change
in the length
of the substrate
material
thatthe
is caused
by anproblematic.
applied metallic
coating.
This
measuresyields
the change
in the
lengthbut
of the equipment
substrate material
is caused by
applied
coating.
This
method
consistent
results,
set-up isthat
complicated
andanthere
has metallic
never been
a manufacturing
method
yields
consistent results, but the equipment set-up is complicated and there has never been a manufacturing
source for
its use.
source for its use.
1. SPECIALTY TESTING & DEVELOPMENT COMPANY SPIRALS
1. SPECIALTY
DEVELOPMENT
COMPANY
SPIRALS
SpecialtyTESTING
Testing &&Development
Co. spirals
are constructed
from 0.010 inch thick stainless steel and each
Specialty
Testing
&
Development
Co.
spirals
are
constructed
from 0.010
inch
thick stainlessinsteel
and each
has a precise surface area of 13.57 square inches. The spiral mounts
on the
contractometer
a manner
has
a
precise
surface
area
of
13.57
square
inches.
The
spiral
mounts
on
the
contractometer
in
a
manner
that permits plating on the entire outside surface of the spiral and discourages deposition on the inside of
that
permitsThus,
plating
on is
thenoentire
surface
the spiral
deposition
on the inside of
the spiral.
there
need outside
to estimate
the of
surface
area and
that discourages
has been plated.
The recommended
the
spiral.
there
is no need
to estimate
the surface
area inch).
that has been plated. The recommended
average
testThus,
deposit
thickness
is 500
microinches,
(0.000500
average test
deposit
is 500 microinches,
(0.000500
inch).
2. PROPERTIES
AND
TESTthickness
CONDITIONS
FOR STAINLESS
STEEL
SPIRALS
2. PROPERTIES AND TEST CONDITIONS FOR STAINLESS STEEL SPIRALS
SPIRAL
NEW CONTRACTOMETER
DESIGN
SPIRAL FOR
THE FOR
NEWTHE
CONTRACTOMETER
DESIGN WITH
A TEFLON COATED INTERIOR
SPIRAL FOR THE NEW CONTRACTOMETER DESIGN
Surface Area, in²
13.57
SurfaceFeet
Area, in²
13.57
Square
0.0942
Squareper
Feet
0.0942 Amps
sq. foot
30
30
Amps per sq. foot
2.90
Amps Thickness, inches
2.90
Stock
0.010
Stock
Thickness,
inches µʺ
0.010
Avg. Deposit
Thickness,
500
Avg.
Deposit
µʺ
500
Plating
Time, Thickness,
Min & Seconds
20 M & 48 S
Time, Min
& Seconds
20
M±&1º48F.S
Plating Solution
Temperature
140º
Plating
Temperature
140º
1º F.
NOTE: Solution
For the purpose
of illustration
and± explanation,
electrolytic plating of nickel will be used.
NOTE: For the purpose of illustration and explanation, electrolytic plating of nickel will be used.
3. TEST PROCEDURE (SPIRAL CONTRACTOMETER METHOD - REFERENCE ASTM STANDARD B636)
3. TESTA.
PROCEDURE
Equipment. (SPIRAL CONTRACTOMETER METHOD - REFERENCE ASTM STANDARD B636)
A. Equipment.
-Spiral Contractometer with calibration weights (PN:2014SC)
-Spiral
calibration
weights
(PN:2014SC)
- SpiralContractometer
Contractometer with
Support
Stand (PN:
2014SS)
--Support
Spiral Contractometer
Support
Stand
2014SS)
Stand Blocks for
use over
hot (PN:
plate-two
required (PN:2014-SB)
-Support Stand
use over
plate-two
(PN:2014-SB)
-Titanium
anodeBlocks
basketfor
3.5ʺOD
for hot
Wood’s
nickelrequired
strike (PN:14ABS)
3.5ʺODforfornickel
Wood’s
strike (PN:14ABS)
-Titanium anode basket 5ʺOD
bathnickel
(PN:14ABL)
-Titanium
anodebeaker
basket for
5ʺOD
for nickel
bath (PN:14ABL)
-4,000
ml Pyrex
plating
bath (other
source)
-4,000
Pyrex
beaker
for plating
bath
(other
-2,000
beakerPower
for Wood’s
nickel
strike
bathsource)
(other
source)
-Directml
Current
Supply
0-5 Amp
output
constant
amp constant voltage (PN: HY3005-PS)
-Direct
Current
Power
Supply
0-5 Amp output constant amp constant voltage (PN: HY3005-PS)
-Magnetic
Stirrer
Hot Plate
(PN:4000-S)
-Magnetic
Stirrer Hot Controller
Plate (PN:4000-S)
-Digital
Temperature
prewired with probe (PN:590TC)
-Digital Temperature Controller prewired with probe (PN:590TC)
2
2
-Spirals constructed from 0.010 inch thick stainless steel having an surface area of 13.57 in²
(PN:2014-SP)
B. Spiral preparation and use.
1. Place the anode basket containing nickel anode buttons in a 4,000 ml Pyrex beaker, then place
the beaker over a magnetic stirrer hot plate, add the desired plating solution to the beaker, then
place the spiral contractometer support stand over the beaker and anode basket and warm the
plating solution to the desired temperature.
2. Pour the nickel strike solution into a 2,000 ml beaker containing an anode basket with nickel anode
buttons along the beaker's inside parameter.
3. Clean a helix as the cathode in an alkaline steel electrocleaner at 5 amps for 45 seconds and
water rinse.
4. Treat the spiral with anodic current (positive charge) for 45 seconds at 5 amps, then change the
current leads to bring negative contact to the spiral and nickel strike the spiral at 5 amps for 60
seconds, then water rinse, acetone rinse and dry.
5. Weigh the spiral to the nearest milligram and record its weight. Note: use finger cots to prevent
contamination of the spiral.
Deposit weight in grams:
6. Mount the spiral onto the spiral holder and tighten the nylon screws through the spiral holes
provided sufficiently to secure the spiral so as to prevent slippage during the plating process.
7. Place the spiral contractometer assembly on the stand and center it by engaging the centering
holes in the top surface of the stand.
C. Calibration of the spiral.
1. Loosen the screw that holds the pulley wheel tight against the top of the center rod and position
the dial by rotating it to match the zero with the arrow, then tighten the screw to secure the rod so
slippage cannot occur.
2. Put the loop of a calibration thread over a pulley calibration pin and wrap the string around the
pulley wheel clockwise, and place the thread and 0.5 ounce weight over the notched Teflon
pin near Kc.
3. Put the loop of the second calibration thread over the remaining Teflon pin near the remaining
Kc. With the weights hanging freely, lightly tap the top of the contractometer pulley to equalize
the dial position. Record the Kc degrees. As an option, the spiral calibration steps can be repeated
and this data can be averaged.
Kc degrees:
Average:
4. Repeat this process again, this time wrapping the threads in a counterclockwise direction and
looping the weights over the Teflon pins near Kt. Record the degrees tensile as Kt. Then
remove the calibration strings and weights. Repeat and average the results if desired.
Kt degrees:
Average:
D. Plating the Spiral.
1. Plate the spiral at 2.90 amps for 20 minutes and 48 seconds. As soon as
possible after the spiral has been plated, tap the top of the contractometer lightly, observe and
record the degrees deflection at the arrow point and the nature of the stress as tensile or
compressive. Compressive stress is indicated by a negative sign.
Degrees deflection caused by the deposit:
2. With the spiral on the contractometer, rinse it in water and isopropyl alcohol, then remove the
spiral from the contractometer using finger cots so as to not adversely affect the weight of the
spiral and dry it thoroughly.
3
E. Calculations.
1. Weigh the dry spiral and record its weight in grams.
Spiral weight in grams:
Subtract from this weight the before plating weight to obtain the weight of metal deposited.
Deposit weight in grams:
2. Calculate the average deposit thickness in inches.
T=
W
=
Inch
Where
D (87.55 cm²) (2.54 cm / inch)
W = Grams of deposit,
D = Density of deposit = 8.90 g/cm³ for
pure nickel, and
T = Deposit thickness in inches.
For the Specialty Testing spirals plated on the new design contractometer, the constant spiral
plated surface area is 13.57 in² and the following formula applies for nickel:
T=
W
= Inches
1979.2
For the spirals plated on the old design contractometers, the surface area plated must be
determined by wrapping the spiral tightly around a half inch diameter rod. Then the diameter and
estimated plated length in inch values are used to calculate the plated surface area as follows:
Surface Area = πdh = inch²
This surface area value replaces the 87.55 cm² value in the above equation.
3. Record the average deposit thickness of the spiral in microinches.
Deposit thickness in microinches:
4. CALCULATE THE DEPOSIT STRESS OF THE APPLIED COATING.
A. Calculate the Deposit Stress in PSI.
Stress = 13.02 (D)(M) x 1 + Eo (d) = PSI where
w (d)
E (t)
D = Degrees caused by the deposit,
w = degrees Kt from the spiral calibration, and
t = Spiral material thickness = 0.010 inch
d=Deposit thickness in inches,
Eo= the Modulus of Elasticity of the deposit = 30,000,050 PSI for pure nickel, and
E= the Modulus of Elasticity of the spiral substrate = 28,600,000 PSI.
Record the Internal Deposit Stress as PSI:
PSI.
B. After each use, loosen the screw at the top of the spiral contractometer and remove the rotate wheel and the
center rod. Water rinse through the top center hole of the spiral support disk, rinse the rod and reinstall the
assembly. Note: This is an Important step.
�
5. STRIPPING OF SPIRALS FOR REUSE.
A. Specialty Testing spirals of the new design are masked on the interior surface with a Teflon coating
that will withstand repeated stripping of nickel deposits in 50% nitric acid solution. These spirals
will withstand temperatures up to 400 ºF.
SPECIALTY TESTING & DEVELOPMENT COMPANY, INC.
137 Reynolds Mill Road, York, PA 17403 USA
Phone (717) 428-0186 Fax (717) 428-0294 www.specialtytest.com