Non-Contact Concentricity Measurement

I am looking for a vendor of equipment that measures insulation concentricity by determining the center of the conductor by induction and the center of the insulation with an X-Y Laser

Dick Kline

Do the companies Beta LaserMike ( www.betalasermike.com ), Sikora ( www.sikora.com/ ) and Zumbach ( www.zumbach.com/e/index.htm ) have no products that can be purchased as a system or integrated into a system for you?

Best Regards,
Peter Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com

Beta Lasermike and Zumbach appear to offer ultrasound systems, which require water baths. Zumbach offers a system which might be of this type, but the maximum diameter of the cable is 0.8". I need 1.5" diameter maximum.

Dick Kline

Please look at the following web page at Zumbach, www.zumbach.com/e/product/metrex.asp The model I am looking at is the Metrex Model A100 continuous, inductive in-line eccentricity and wall thickness monitor.

It works in air but unlike your wishes and as I recall, the spring loaded, rotating transducer is in direct contact with the cable. This model has an outer diameter over insulation range of 0.08 to 5.9 inches. It also has an eccentricity measurement range of 0 to 0.4 inches.

If you wanted to add any X-Y laser monitor to this, integrate all the readings and display them graphically on a CRT, it should certainly be possible. In fact Zumbach (See their Odex concept), Beta or Sikora may even do that for you.

Because the Metrex unit contacts the cable however, it is a bit of a pain for the extrusion operator to set up each time. Perhaps Zumbach will supply you with a demo model for a short evaluation.

Other non-contact eccentricity monitors as you have already pointed out are usually ultrasonic and they requre that the water bath and plastic stay at a reasonably constant temperature. That is one of the reasons for placing the transducers close to the cross-head (along of course with the minimized measurement time delay).

Non-contact induction units would in my experience measure the coaxial capacitance to ground of the insulated conductor in a water bath and thus would infer and quantify eccentricity from a non-normal reading. These work in conjunction with laser diameter monitors (X and XY) so it is first verified that the insulation is not oval, oversize or undersized. Here you would also need a reasonably constant water and plastic temperature.

Non-contact position sensors in dry-cure CCV lines work on an induction principle but the accuracy for actual eccentricity measurement is in my understanding far, far too crude even if the cable position was rock solid. Thus dry cure CCV lines often employ X-ray or nuclear (gamma ray) eccentricity and diameter monitors outside the pressurized equipment but usually near the pressurized splice box, at the cross head.

Best Regards,
Peter Stewart-Hay
Principal
Stewart-Hay Associates
www.Stewart-Hay.com

UPDATE January 21, 2009
Takikawa Engineering (Japan) claims to have in-line non-contact eccentricity instrumentation for sale. See www.takikawa-eng.co.jp/

I would also look at Sikora. We have tried others and now use them exclusively for concentricity measurements when extruding PE foam

You may also consider the new Proton gauges ( www.protonproducts.com ). This company is promoted by the ex-engineers and owners of Beta Lasermike.