Original title: See how Wassara, a mining company, uses metal 3D printing to solve deep drilling problems? The mining industry needs new drilling solutions to cope with increasing cost versus benefit pressures. Compared with the current drilling scheme, the new scheme is not only more environmentally friendly, but also more economically advantageous. Many existing underground mines are close to the limit of mining depth, so it is difficult to ensure the controllability of various costs by current drilling methods. The new deposits are deeper and less productive. The combination of various factors requires mining enterprises to realize the rational planning and large-scale exploitation of mineral resources, so the adoption of more efficient and accurate drilling methods has become an inevitable choice. Background Wassara, a mining equipment company from Sweden, has a number of innovative products that minimize the negative impact on the environment while mining ore. Wassara's core technology is a down-the-hole (DTH) hammer driven by a high-pressure water jet. Wassara's hydraulic down-the-hole hammer is the most environmentally friendly method of percussive drilling available. Dth hammers are driven by high-pressure water jets and do not use grease for lubrication,dth button bits
, so they do not pollute the air or groundwater. In addition, high-pressure water is effective in suppressing dust. The incompressibility of water is a key factor in the efficient operation of the Wassara Dth hammer. Wassara's technology results in significant energy cost savings compared to relatively conventional pneumatic Dth hammer technology because less energy is required to drive a hydraulic Dth hammer. High pressure water was selected by Wassara as the transmission medium due to its ability to drive the hammer to produce high frequency, high energy impact motion. In addition,dth hammer bit
, when the flow leaves the hammer, it is fast enough to bring the drilled core and debris back to the surface and clean the hole. This technology has many excellent advantages, such as high drilling efficiency, good borehole quality, and strong wall protection ability for drilling rock formation. With the addition of liquid drive Dth hammer technology, mining enterprises have more choices when choosing the most suitable mining method for ore body characteristics, which is regarded as a big step towards scientific mining. Expand the full text Challenge Each down-the-hole hammer is made up of a number of complex components. The core component of the down-the-hole hammer is a sliding shell which provides two-way high-pressure water diversion for the piston assembly, dth drilling hammer
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, and the inside of the shell requires a plurality of high-pressure water flow holes; due to the complexity of the design, a plurality of processed parts must be jointed together to manufacture a complete shell. The complex design also makes the component relatively expensive to manufacture. In addition, the total cost of ownership of the down-the-hole hammer is further increased by the frequent occurrence of non-conforming products during the joining process, as well as equipment failures due to component wear or pitting during use, which increases maintenance costs. Solutions Wassara approached Renishaw to find out whether additive manufacturing (AM) technology could be a suitable alternative manufacturing solution in order to reduce costs and improve the reliability of sliding enclosure components. One of the significant advantages of metal additive manufacturing is the ability to combine discrete parts into a complex 3D geometry and simplify the processing steps, for example, when processing cross-holes requiring blind plugs or welding at one end. When there is no significant difference in design between the components manufactured by additive method and the components manufactured by traditional method, they can be tested in the same application environment, and the results can be used as an ideal basis for verifying the usability of metal additive components. A detailed comparison of the performance of the two types of components under standard test conditions, with any significant differences in the results directly attributable to changes in manufacturing technology. The geometry of the Wassara sliding enclosure has been redesigned to incorporate the benefits of additive manufacturing in terms of design freedom. The next challenge to overcome with a metal additive manufacturing solution is the use of the appropriate metal alloy for the particular application. In this case, the component originally used standard alloy steel 527 M20, an alloy structural steel that would not normally be used for metal additive manufacturing due to its medium carbon content.
The alloy steel more suitable for additive manufacturing is 316L stainless steel. However, although this alloy steel has better corrosion resistance, it is not expected to guarantee sufficient corrosion and erosion resistance during service. Another alternative proposed by Renishaw was to produce test parts using maraging alloy steels. Maraging steels are age-hardening tool steels with a wide range of applications; they can be heat treated to obtain material properties tailored to the requirements of specific applications by adjusting the process temperature. This is the first test and application of this type of steel in the field of mining, so the sliding shell was heat treated after machining to ensure maximum hardness. Result To test the performance of the additive sliding shell, Wassara assembled it into a complete down-the-hole hammer for test use under standard mining conditions, i.e., drilling a typical long passage hole in a selected rock face. Routine visual inspection and maintenance of the down-the-hole hammer followed, and the additively manufactured sliding housing showed no signs of pitting and minimal wear compared to the conventional housing. The down-the-hole hammer was then reassembled and more drilling operations continued. Upon completion of the above work, Wassara performed a second inspection of the additively manufactured sliding enclosure and found that there were indeed some signs of wear, but other than that, there was no pitting on the surface of the component (the second most common cause of equipment failure). A third drill test was then carried out by Wassara,DHD Drill bit
, this time for a duration well beyond the normal Dth hammer cycle, in order to establish as far as possible whether there was any evidence of pitting, but there was still no pitting. This leads to the preliminary conclusion that additive components made of maraging steel have superior potential pitting resistance compared to conventional sliding enclosures made of standard alloy steel. Return to Sohu to see more Article Source: Renishaw Responsible Editor:. wt-dthtools.com