Cones

Very many aspects apply to selection of the best-suited penetrators.

In general and as an initial approximation, we can state the following: The harder and more solid the material to be measured, the more pointed and needle-like the penetrator should be.

Unless standards or other measuring regulations require the use of special penetrators, the non-standardized SUR-cones should be used for optimize testing. Due to their more simple shape, they are not only more favorably priced, but also afford the advantage that their shape remains unchanged over the entire penetration depth, producing comparable measured results on materials with low or high penetration values.

This is not always the case with the standardized cones with an offset tip.

"Half-scale-cones" and "Quarter-scale-cones" in addition to various types of "Micro-cones" are available for measurements on small sample quantities. In certain cases, special sample containers are recommended.

Note: if using conversion formulas which permit measured values to be converted to the penetration depth which one would have obtained if using the corresponding standard cone, the measuring inaccuracy is also increased proportionately.

Perforated Disks

Since it difficult to position the disks on the surface of the sample, the "immersion-start" method is frequently used, i.e. the starting position of the perforated disk is selected beneath the sample surface and the measurement is conducted from this point.

The method of measurement with perforated disks is similar to the measuring principle of the falling-ball viscometer.

In cases of specific substances (in laboratory tests) it is possible to obtain analogies to the dynamic viscosity values.

The use of centering devices (e.g. centering disk 18-0119 for sample container 18-0103) is recommended for precise centering of the measurement disk.

When using perforated disks, it is important that the sample container are sufficiently large in order to prevent wall effects influencing the measurement.

Alternately the shape or size of the sample container for the measurement is selected precisely so that possible wall effects remain a constant factor in measurement.

Penetration Accessories - Cones & Disks

More details are mentioned in the "Order Number" section