Mining Tools

JascoWessex Jasco Division have developed a range of rock drill re-sharpening tools which will be marketed under the product range of Jasco.

A new system for the re-profiling of tungsten carbide buttons incorporated in button bits, developed by the original JASCO team which were the first to develop the original SCANDIA and BOROSCAN range in the mid 1970's 

The original system has been copied many times since using cheaper raw materials and has even been called Scandia, COMBOS and Boroscan by other manufacturers which is a compliment in itself.
 
However, even with the best there eventually becomes a time where it is left behind with progress and a greater understanding of what is actually required to re-profile an individual button without in fact further damaging it.
 
Wessex Jasco Division have applied over 50 years of diamond tool expertise to further develop the application with improved manufacturing techniques and advanced Diamond and CBN specifications.
 
Our Jasco COMBO combination tools actually contain a separate Diamond and CBN section which is not the case with current copies of our original product.

 

Rock Drill Sharpening

Rock Drill Sharpening

A button bit should be re-profiled when its rate of penetration drops to less than 80% of the original rate, or when the carbide buttons show an unacceptable amount of damage.

This damage usually shows either as chipping or an “Orange peel effect”. This is caused by damage to the Tungsten carbides’ cobalt matrix cracking due to excessive heat. This can be caused either by a “Lack of protrusion ” of the button above the base metal steel body of the bit or using a re-profiling diamond tool with the wrong grade of diamond or bonding material.

Small-gauge button bits, especially if they are used in hydraulic rock drills, will normally never need any regrinding.

Large button bits on the other hand, will need regular re-grinding.

Normally, the rate of penetration drops off significantly when buttons are worn flat to 30% of their original diameter. It is then that the recommended approach is to re-grind buttons at that stage. This invariably returns the penetration rate to it’s original levels.

Gauge buttons will usually wear quicker than face buttons and, therefore, require regular inspection and re-grinding.

If this is not done, then it can cause the bit to “jam” in the bore or even fail, which is an expensive operation to rectify.

The cemented carbide buttons must be re-ground to restore their original profile whether it be hemispherical, ballistic or conical profile.

The only effective method of restoring these profiles is to use a Diamond grinding pin impregnated with graded diamond powder in a metal bonded matrix.

Cbn grinding pins are available for removing the base steel surrounding the button to achieve the correct protrusion of the carbide button from the steel base whenever this is necessary.

Cemented carbides should not be exposed to excessive heat when re-grinding, as this will result in cracking the carbide leading to premature bit failure and shorter life between re-grinds.

All grinding machines should incorporate a water cooling system where climate conditions permit or an anti-freeze solutions in the colder climates, which keeps both the carbide buttons cool as well as flushing away ground metal particles.It is a myth that the best pins are those that last the longest as a hard bonded pin is just as capable of imparting damage to a carbide button as the rock formation itself.

For more information please contact us on jasco@wessexint.com

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Rock Drill Sharpening | Diamond Sharpening

 

 

Wessex International Tooling Ltd.
Ashelford Farm Barn, East Down, Nr Barnstaple, North Devon EX31 4LU
United Kingdom

Phone +44 (0)333 011 7471 / +44 (0)1840 269 002
Fax +44 (0)1626 834 011

E-mail sales@wessexint.com
Skype johnofwessex

 

Company name: Wessex International Tooling Ltd
Place of registration: Cardiff, United Kingdom
Registered number: 5327097
Registered office address: 7 St Pauls Rd, Newton Abbot, Devon TQ12 2HP
United Kingdom

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