This type of casing shoe uses seismic grade tungsten-carbide as the cutting media. Tungsten-carbide does not possess the hardness of diamond and as such has a limited range of application as a drill tool cutting media. Tungsten-carbide casing shoes are however a very cost effective means of drilling through softer unconsolidated formations. There are two types of tungsten-carbide casing shoes produced by Dimatec: the “carbide-chip” and the “saw-tooth” types.

In addition to casing shoes, Dimatec also manufactures tungsten-carbide rod shoes. In terms of design, rod shoes are very similar to casing shoes and differ only in their thread connections. Rod shoes are used where wireline drill rods are used as casing tubes.

Saw-Tooth Tungsten-Carbide Casing Shoes and Rod Shoes

These tools are set with large, rectangular-shaped tungsten-carbide elements that are physically embedded into the crown of the tool. The bit face has an aggressive saw-tooth pattern with integral canal type waterways. The bit crown itself is composed of a tough, wear resistant metal-bond matrix material. The gauge diameters of the tool are also heavily set with tungsten-carbide wear pads.

The application of this type of tool is primarily in geotechnical soil investigation or for advancing casing tubes through overburden layers that are composed mainly of clay, sand, gypsum or soft shale

Carbide-Chip Casing Shoes and Rod Shoes

The cutting media used in this type of casing shoe are crushed tungsten-carbide chips that are suspended in a metallic alloy that is fused to the steel body of the tool. Typically, these tungsten-carbide chips have a granular size 0.08 to 0.20 inch (2 to 5mm) and have a totally random orientation within the bit crown. The face profile is somewhat irregular and the waterways are of the standard canal type (Style “W”) design.

This type of casing shoe crown has considerably more cutting edges than the “saw-tooth” variety and as such has a wider range of application that includes slightly harder sedimentary formations.

Carbide-chip casing shoes are similar to impregnated diamond casing shoes in that the bit crown is composed of several layers of cutting media. The tool face regenerates itself with new cutting edges by wearing away the metallic alloy during operation to continually expose new layers of carbide-chips until the tool crown is consumed.