Metric Formula for the Spiral Contractometer System:
Calculations for the Deposit Thickness using Specialty Testing Spirals (Helices):
- Subtract the start weight (SW) from the finished weight (FW) to obtain the weight of metal deposited.
. FW – SW = W
- Calculate the average deposit thickness in inches. (for D density, see Chart A below)
. T = ____W_____
. D (87.548212 cm²)
For Specialty Testing Spirals/ Helices the surface area is 87.548212 cm ²
W = Grams of deposit
D = Density of plated material, g/cm³
T = Deposit thickness in cm.
- Record the average deposit thickness of the spiral (helix) in cm: T = ______________cm
Chart A, Density and Modulus of Elasticity for Metric Systems
|Deposited Metal||(D) Density||(Edeposit) Modulus of Elasticity in kg/cm2|
- Calculate the Deposit Stress in kg/cm² using Specialty Testing Spirals/Helices only:
. Stress = 2.54 (d) X 1 + EDeposit (T) = ________________________ kg/cm²
. (K) (T) 4926656
d = deflection of the spiral (helix) caused by the deposit in degrees after plating,
K = deflection of spiral (helix) on calibration in degrees= before plating Kt or –Kc, if the bath is tensile use (Kt value) or compressive use (-Kc value).
T = deposit thickness in cm, (found in #2 on previous page)
t = substrate thickness in cm, for Specialty Testing Spiral (helix) is .0254 cm,
EDeposit = Modulus of elasticity of the plated material _____________kg/cm², (see Chart A on previous page).
ESubstrate = Modulus of elasticity of the helix substrate= 2,010,880 kg/cm² for Specialty Testing Spiral (helix).
NOTE: If using Other Spirals/ Helices the Metric Formula would be (if using other Spiral Contractomters we can not guarantee these results-due to slippage and other issues):
. Stress = 2.54 (d) X 1 + EDeposit (T) = _______________ kg/cm²
. (K) (T) ESubstrate ((t) x 100)
. 5. STRIPPING SPIRALS (HELICES) FOR REUSE.
. 1. Plated spirals (helices) can be stripped of deposits repeatedly in a 50% by volume nitric acid solution for reuse. Do not heat the solution above 32°C
. 2. When the exterior surface of a spiral (helix) shows visible etching, the helix should be discarded.
Note: If stripping Silver, Gold, or Copper see our website under Procedures/Stripping Deposits from Spirals (Helices). Visit: https://specialtytest.com/procedures/deposit-stripping-helices/