Understanding Hole Openers
At some point it may be necessary to increase the size of a pre-drilled hole to a larger diameter or to drill large diameter holes.
Hole opener bits are designed specifically for this purpose. Bits are custom manufactured in a wide range of styles to meet field requirements.
A custom hole opener is an effective way of enlarging holes, hence the name "Hole Opener".
There are many variations, all of which are tailored to the driller's specific needs. Hole openers can be fabricated with steel tooth
cutters, tungsten carbide insert cutters or for DTH hammers, all either new or rebuilt. Bearing may be open or sealed and the hole opener
may utilize either standard or reverse circulation. Hole openers may be the answer to your hole enlargement problems.
TCI(Tungsten Carbide Inserts) Cutters are available along with diamond enhanced features. Fixed cutter hole openers are made from sections
of tricone bits as shown left (TCI cutters) and below (Tooth cutters). Steel Tooth Cutters are available with carbide tipping.
Today, drillers are more adept at replacing their own cutters. Your supplier can provide the replacement cutters which saves you shipping the hole
opener to and from the manufacturer for repair.
Straighter Holes - By drilling a smaller hole with a "pilot" bit, then attaching that
said bit onto the bottom of the the hole opener. The hole opener will follow the path of the hole drilled by the smaller bit.
Larger Holes with Smaller Rigs - By drilling a hole in stages, larger holes can be drilled
with smaller rigs. A smaller hole requires less power.
Replacing Cutters and Cutting Cost - On most Hole Opener designs, the cutters can be easily
replaced. The cost to replace a cutter is a fraction of the cost to replace a large tricone rock bit.
Cost of Large Rock Bits - Larger diameter rock bits not only cost a lot,
they can be difficult to find. A more economic solution is to use a hole opener that uses smaller tricone rock bit segments..
Flexability - Hole Openers can be fabricated in just about any size, and can be configured
to drill through any formation.
Drilling Weight - The choice of drilling weight is determined based on the recommendations
of the bit manufacturer and the number of cutters on the hole opener.
Number of Cutters
- The number of cutters placed on a hole opener is governed by the following facts:
- Maximum number which will fit around the perimeter.
- The greater the number of cutters, the less the weight, which therefore reduces the penetration rate.
- In softer formations, less weight is needed to penetrate.
- The greater the number of cutters, the smoother the tool will run.
- The greater the number of cutters, the greater the cost.
- The greater the number of cutters, the longer the cutters will last
Rotary Speed - Maximum speed is determined by the manufacturer's recommendation and the
calculation to account for the linear distance the cutter is moving per revolution.
Hole Cleaning - A frequently over looked point of hole opener operation is hole cleaning.
The volume of cuttings to remove from a hole increase by a squared factor with an increase in hole diameter.
DTH hole openers provide hole enlargement for hammer drilling. Custom pilot and head diameters are available in most all shank designs.
Shown right is an example of a 2-stage hole opener with a pilot bit. The pilot hole was drilled followed by the first stage to enlarge
the hole. The second and final stage then further enlarged the hole to 54". Different stages can be built per drillers specifications to
maximize cutting removal and rig capabilities.
To the left is a mammoth 66" fixed cutter hole opener with a 4" bore and flanged for reverse circulation.
- Interested in our Hole Openers - Click Here
- Click here if you are interested in our Tricone Cutters - Steel Tooth and Tungsten Carbide Insert(TCI)/Button
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