The authoritative public forum
  for Metal Finishing since 1989
  

  -----

Spiral Contractometer Test

September 29, 2009

hello, please help me:

I have accomplished only two times this test at a plate of nickel sulfamate and I have some question.

I have a lot of variation when the contractometer measure the diameter of the placed spiral. ( differences of diameter of to 0,016 in ) the mandrel is lightly twisted. it indispensable than the mandrel this perfectly concentric with the exis of contractometer ?



Thanks.

MARIA LOPEZ
ENGINEERING - MEXICO

---

First of two simultaneous responses --

Your measurement is done in a clamped position with it moderately tightly wrapped to a mandrel and the coils snug to each other. This is for an area measurement. When you load the coil on the unit it is a "lose fit and you will frequently have some differences in the diameter and the spacing of the coils. If you are in doubt, get a new coil that is not significantly damaged. Doing a monthly test, I got about a year from each coil, with some being longer.

James Watts
- Navarre, Florida
October 3, 2009

---

Second of two simultaneous responses --

The initial or final position or diameter of the spiral are not significant. What you want to determine is the variation before and after the plating which in turn directly relates to its internal stress. No stress, no twisting (variation).

Guillermo Marrufo
Monterrey, NL, Mexico
October 5, 2009