Thompson, CT USA

Numa, a leading designer and manufacturer of down hole hammers and bits, has announced the opening of a bit button repair and replacement facility in their state-of-the-art manufacturing center in Thompson, Connecticut.

This facility is equipped with the latest tools and utilizes the newest techniques for repairing and refurbishing down hole hammer bits to a virtually new form. Furthermore, the staff is backed by over 15 years of experience and is adeptly skilled at repairing many types and styles of severely worn or damaged bits. Numa is currently accepting all manufacturers’ bits in sizes from 3-1/2 to 48 inches (89 – 1219 mm) in diameter.

buttonremoval-02The tungsten carbides that are used in down hole bits for percussion drilling must be kept sharp and at the proper height in order to maximize the penetration rates and the life of the bit. Conducting scheduled maintenance in many cases helps to extends the life of bits by avoiding much of the down time related to failures of over-worn bits and can help to keep the carbide cutting at optimum speed. Numa’s new bit button repair and replacement facility has been established to meet these needs.


buttonremoval-03Most commonly used bits today have spherical carbide buttons and, as the bit wears, the shape of the button can develop a flat spot. The standard rule of thumb is that when the size of the flat spot reaches 1/3 the diameter of the original carbide size, it is time to sharpen the bit. As an example, a bit with 5/8″ (15.9 mm) carbide will need to be sharpened when the flat size is 7/32″ (5.6 mm). If sharpening does not occur at this point, the driller will see slower penetration rates and increase the risk of breaking the carbide buttons.

buttonremoval-04Another important aspect of bit maintenance is the height of the carbide button. In some formations, the steel may wear away more quickly than the carbide and cause the carbide to protrude too far from the steel matrix. This is a condition that makes the bit appear as though it has frog eyes and if it is not repaired will create an excessive torsional load on the carbide. Without the steel matrix for support, the carbide has the ability to move in its socket and will eventually fail. In other formations, the carbide can wear faster than the steel matrix resulting in a bit with carbide that is too close to the steel matrix. This will prohibit the bit from efficiently fracturing the rock and slow the penetration rate considerably. The rule of thumb is that the height of each carbide should be 1/2 the original diameter of the carbide size. If the original carbide size is 5/8″ (15.9 mm), the carbide height should be less than 5/16″ (7.9 mm). If it is greater than 5/16″ (7.9 mm), the carbide must be ground down to the proper size. If it is less than 5/16″ (7.9 mm), one may elect to grind away the steel so that the carbide has the correct protrusion.

buttonremoval-05Continued use of bits with fractured and/or broken carbide inserts may lead to catastrophic damage. Numa offers a service to remove this carbide and replace it in order to extend the life of down hole bits. In order to remove the carbide, the Numa repair facility utilizes a proven method without applying heat that leaves the carbide button socket undamaged and ready for replacement.

Numa’s bit button repair and replacement facility is dedicated solely to improving the performance of worn bits. However, in addition to sharpening the carbide buttons and grinding the steel down to make sure that there is proper carbide height, Numa also offers its repair customers access to its extensive lathe capabilities to address major or minor bit body imperfections. Additionally, Numa’s Metal Improvement Department is available as a resource to assist in surface finish detailing and other improvements.

Numa president Ralph Leonard states, “The bit button repair and replacement facility is yet another example of Numa’s commitment to serving the drilling industry. This facility helps to ensure that drillers are getting the most out of the investment they make in down hole bits. The service truly allows hammer and bit owners to drill more total footage for less.”

Numa is a major manufacturer of down hole hammers and bits for the international drilling industry. The company designs and builds down hole hammers and bits for drilling vertical and horizontal holes 3-1/2 to 48 inches (89 – 1219 mm) in diameter. The company is known worldwide for their Patriot hammer line that provides an unmatched combination of fast penetration rates and long hammer life.