Chris Lambert has a bachelor’s degree in mechanical engineering and has been with Boart Longyear since 2008. He has been the company’s global product manager for coring tools, including rods, in-hole tools and diamond bits, since 2012. Prior to that, he was the engineering manager for diamond products. His 20-year engineering and product development career has included materials, hydraulics, pumps and diesel engines.

Our new host, Jon Peterson (Geo Jon for fun), works for the Products division as a Customer Service Representative. Jon graduated from the University of Utah in 2015 with his Bachelors of Science in Geology. He’s worked for Boart Longyear for the last two and a half years and interned as a geologist with an exploration company for about six months prior to coming to work for Boart Longyear. Jon has been married for a year and a half and in his free time enjoys trail running, hiking, working on his yard, spending time with family, and playing with his black lab Dexter. 

Learn more about the Longyear bits.

We would love to hear your questions and comments below. Thanks for listening and if you liked this episode, share it on LinkedIn, Facebook, or Twitter. 

During the recent market downturn, many drill rigs had been sitting idle, which made it easier to cannibalize components and parts to keep actively drilling rigs running. Most drillers were repairing the rigs they had to keep them drilling without investing capital in new drill rigs and technology. Now that the market is slowly increasing, many drilling contractors are making decisions on their fleet as to whether they should rebuild the idle rigs or buy new rigs.

Operations managers know which components (engines, valves, assemblies, etc.) need to be replaced and they typically have a fairly accurate idea of the cost to rebuild idol drill rigs in the fleet. If the rebuilding costs are close to what it would cost to buy a new drill rig, they may choose to do a full-blown audit, inspecting each of the drill rigs, evaluating spare parts in stock, and checking maintenance records for a more accurate comparison of the costs to get a drill rig ready to work again.

Besides just costs, other factors include whether the drilling company has the time, talent, and capabilities to do an overhaul on a drill rig that has been idle and needs work. An overhaul can take three to four months and requires the facilities, tooling, a labor pool of mechanics with the time (they may already be working on other rigs to keep them running), and the knowledge to get drill rigs ready to mobilize for drilling contracts.

With the improving market, everyone can expect longer lead times – whether you’re rebuilding or buying new. When the market is in a decline or really low, inventory is higher, plants aren’t as busy building new rigs, and lead times are reduced. As the market improves and contracts increase, inventory is lower, plants are busier building more rigs and lead times tend to be increased. Ultimately, lead times vary based on the manufacturer.

LF90D surface coring drill

If you have an older drill rig fleet, buying a new drill rig provides an opportunity to drill more productively for more meters. Newer rigs are generally more productive, provide more reliable uptime, and have a lot more built-in safety features than older rigs. With increased mine site safety requirements, a new rig can meet those new safety requirements where an older rig might not make the grade and cost a drilling contractor a contract award.

Drill rigs with rod handling equipment generally have crews with fewer hand and back injuries, and less overall stress and strain. Mechanized rod handling also saves on labor costs and staffing as an extra crew member is not needed to manually handle rods. Plus, becoming known in the market as the drilling service provider that has updated equipment with rod handling capabilities will likely get you invited to more bids. When rod handling was first introduced, productivity suffered as the machine rod handling was not as fast as manual rod handling. However, with the newer technology, productivity can be maintained.

FL262 FREEDOM Loader and LF160 Surface coring drill rig

Used drill rigs typically break down more often than new rigs and that down time can affect hard-earned drilling contracts. The costs can quickly start piling up from loss of productivity, rig uptime contractual obligations, and repairing the drill rig. Not only does the well-maintained operating condition of a drilling fleet help productivity, but it can keep a contractor from getting kicked off a contract or site.

When one finds themselves in the market for another drill rig, the first question is whether to buy a new or used drill rig. It tends to be harder to find gently used equipment, and when in the market for used drill rigs, it’s difficult to be sure how well or harsh the rigs were treated and used in the field. Hydraulic systems, for example, are very delicate and if they’ve been mistreated or there is contamination in the hydraulic system, it can be extremely expensive to replace pumps, motors, or valves. It can be a risky purchase if the history and maintenance of the drill rig aren’t known.

There were a lot of great buys in the market downturn, but as the market continues to improve, price points are going to increase and availability decreases.

LM110 Underground coring drill rig

When purchasing a new exploration or production drill rig, it can be tempting to shop on price because there are a lot of low-cost options out there. However, just like any other major purchase, it is important to evaluate the total cost of ownership. Lower priced drill rigs can actually have a higher total cost of ownership. Taking the time to price out important replacement parts and spare parts can prove to save money in the long run.

The other thing to consider is the availability of those components. When buying a low-cost drill rig from a company that doesn’t have a global footprint, the local availability of spare parts and the lead times to get replacement components can impact your bottom line. Many smaller manufacturers only support customers on a regional basis.

The reliability gained by purchasing high-quality components means not having to replace components as often, which means more uptime and spending less money to operate that rig than if you buy something at a lower price point.

Which comes first, the new drill rig or the contract win to put it to work? This is a good question and it really depends on lead times. Talking in context of the current market where there is a bit of growth, the competition to win a bid depends on when you can mobilize and get to site to start drilling. Lead time to get onsite to start drilling can be extended if you wait for the contract win to purchase a new rig versus having the rig ready to dill – contractors may want to pre-purchase equipment and go to bid with a drill-ready fleet. This is more important now than it was, say, last year or the year before.

Major mining companies can mandate technology and safety upgrades and are always in discussions about improving safety, taking advantage of innovations, and implementing technology. You need to have a competitive advantage that meets all of the operating requirements, but anything above and beyond can make you stand out from other drilling contractors. For example, having rigs equipped with rod handling can provide the competitive advantage that wins the project.

Take time to consider your options. Evaluate your current drill rig fleet and consider what it will take to get everything maintained and updated to be competitive. Does your drilling rig take advantage of recent innovations and meet the latest safety standards? If repairs and available parts outweigh returns, look at updating your fleet. The number one reason to buy new equipment versus used equipment is to enhance productivity, improve safety, and enjoy long-term reliability.

If all the gains from purchasing a new rig makes sense, talk to an expert to see what is available that meets your needs both now and in the near future.

The SMA recognized Boart Longyear as the mining contractor with the best safety stats in 2017. The hours worked in 2017 included a specialized shaft sinking project and the demobilization of the Cameco McArthur River as the mine moved to care and maintenance.

The SMA uses reported stats for safety incidents including first aid medical consultant frequency, medical incident frequency, modified work days severity, lost time injury, and days lost severity to base the recognition.

SMA is an industry-driven organization representing the mining and mineral exploration industry with over 25 mining operations in the province. The Saskatchewan Mining Association is an industry-funded organization that has been in existence for over 50 years. The SMA is considered by provincial and federal governments to be the Voice of the Mining Industry in Saskatchewan. SMA represents its members by engaging in government advocacy, public awareness, including educational outreach and member development.

Below, pictured left to right: Rob Jackson, SMA Board Liaison to Safety Committee, Honourable Bronwyn Eyre, Minister of Energy & Resources, Jimmy Barrieau, EHST Regional Manager, Boart Longyear and Mike Carr, Deputy Minister, Labour Relations & Workplace Safety

Rotational speed has a direct influence on the penetration rate of bits. If the speed is doubled for a given depth of a cut, the penetration rate also doubles. For this reason, rotational speed is typically set at a fixed value based on the size of the tools being used. If the rig has sufficient torque, the speed can be increased to get higher penetration rates. Conversely, if the head stalls under normal operation, then the speed should be reduced to produce more torque and maintain steady rotation. The exception to this rule is drilling in extremely broken and hard ground. Broken ground is free to move so instead of cutting, the rock is removed by a grinding action. Under these conditions (three body wear), diamond bit wear is extremely rapid and rotational speed should be cut to half RPM and weight on bit sufficient to reach 1 to 2 ipm (3 to 5 cpm).

If the head stalls under normal operation, reduce the speed to produce more torque and
maintain steady rotation.

In broken ground, cut RPM in half and apply sufficient weight on bit to reach 1 to 2 ipm 
(3 to 5cpm).

Weight on bit (WOB) is the main method of controlling bit life and penetration rate. If very high bit loads are required to cut the rock, select a higher series bit to prevent increased hole deviation, excessive core barrel, and rod wear, and even down-hole failures. Increasing the bit series normally results in lower bit weights required for the same penetration rates. If weight on bit is too low, both the penetration rate and torque drops, resulting in low life and productivity. This condition is referred to as polishing and describes the phenomenon of diamonds wearing faster than the matrix until the face is flat, leaving no diamonds protruding from the face. Polishing is caused by the friction and heat accumulating in the diamond as it rubs rather than cutting the rock. If weight on bit is too high, characterized by very little or no increase in penetration rate for additional weight, the result is constant sharpening and rapid wear.

WOB is too low if the bit polishes and torque drops. Results in low life and penetration rate.

WOB is too high if added weight does not increase penetration rate. Results in constant sharpening and rapid wear.

Sharpening of the bit results from burying the diamond in the formation and creating contact between the matrix and formation. The friction on the matrix removes it and exposes new diamonds. Sharpening is beneficial when bit penetration has dropped due to wear on the diamonds but if left in a sharpening mode the bit is consumed very rapidly. As rods are added, force to maintain constant weight on bit will change, so weight on bit must be monitored to ensure consistent bit performance at all depths. The weight of the rods and the down force developed by the hydraulic cylinders provide the force exerted on the diamond bit. Unfortunately, drill rig controls do not display weight on bit but instead display feed cylinder pressure.

The weight on bit or force can easily be found by the following "off bottom" method:

1. Suspend the rods with the hydraulic system in the lowering position.
   
   
2. With the drilling motor running at a drill rotation, note the reading on the cylinder feed pressure gauge. This is approximately equal to the hydraulic pump pressure plus the weight of the rods in terms of hydraulic pressure. This is called the “off bottom” pressure.
   
   
3. Rotate the rods and feed them down by opening the restrictor valve. As the bit touches bottom, part of the weight of the rods is supported on the bit. This action is indicated by a decrease in the gauge reading. The difference in the gauge readings is the pressure applied to the bit.
   
   
4. The pressure applied to the bit multiplied by the area of the hydraulic cylinders gives the force or weight on bit.
   
   
5. The bit torque can be measured in a similar fashion by comparing the “off bottom” hydraulic pressure of the rotation unit to the hydraulic pressure while drilling.

Torque generated by the bit is a function of sharpness of the bit and weight on bit, and results from the diamonds cutting the formation. As such, torque should be viewed as beneficial and an indication of drilling effectiveness. Minimum torque occurs just after bit sharpening has completed and as bit weight is reduced. Maximum bit torque occurs during bit sharpening due to the bit matrix coming into contact with the rock. A simultaneous decrease of torque and penetration rate indicates that the bit is polishing and needs to be sharpened. Torque increases due to sharpening should only be a concern in lost circulation or when sharpening requires water restriction. Bits with large diamonds can drop or stall RPM when sharpening. If RPM drops during sharpening then a lower gear or speed should be used to increase available torque.

Decreasing torque and penetration rate indicates bit polishing.

Maximum bit torque occurs during bit sharpening. Only be concerned with torque rise when restricting water or in lost circulation.

Fluctuation in torque, particularly during sharpening is caused by unstable rock fragmentation and/or insufficient rock penetration. Weight on bit needs to be maintained to establish secondary fracturing and stable cutting.

If the head stalls under normal operation, then reduce speed to produce more torque and maintain steady rotation.

Bits with large diamonds can drop or stall RPM when sharpening. If RPM drops during sharpening, then a lower gear or speed should be used to increase available torque.

The cutting rate varies as a result of weight on bit, sharpness, bit formula, and ground conditions. Typical penetration rates vary anywhere from 2 ipm to 12 ipm depending on bit formula and formation. As formations become harder, the penetration rate should be reduced to achieve good bit life. In extremely broken, hard ground, drill at half RPM and weight on bit sufficient to reach 1 to 2 ipm (3 to 5 cpm).

Penetration rates vary anywhere from 2 ipm (5 cpm) to 12 ipm (30 cpm) based on bit
and formation.

In extremely broken, hard, ground, run at half RPM and weight on bit sufficient to
reach 1 to 2 ipm.

The penetration rate to prevent polishing mode may be higher in large diamond bits.

The flow of drilling fluid in the drill hole serves many purposes including the essential cooling of the diamonds, removal of cuttings, and attainment of good bit life. High penetration rates require additional flow to keep cuttings off the bit face, as do higher rotation rates. There is no maximum water flow rate, though at high-flow rates, the bit can be lifted off the rock face, causing it to polish. Free-cutting bits obtain maximum life and penetration using plenty of water.

High penetration and/or rotation rates require additional flow.

There is no maximum water flow rate. At high pressures, the bit can be lifted off the rock face, causing it to polish.

Free-cutting bits obtain maximum life and penetration using plenty of water.

The positive displacement pumps typically used on drill rigs pump water in proportion to how fast they are spinning; the faster they spin the more they pump. The amount of water pumped will be nearly the same over a very large pressure range and for this reason, water pressure does not tell the driller anything about how much water is flowing. For a driller to calculate water flow, they should measure the water pump shaft rpm with a tachometer, and then compare the measured shaft speed with the max speed listed on the nameplate. If the shaft speed is half of the max speed then the water pumped will be half of the listed flow at max speed. The other method is to disconnect the outlet hose and run it to a 5 gallon or 20-liter bucket and time how long it takes to fill. The flow rate is the time in seconds divided by 60 multiplied by either 5 gallons or 20 Liters.

FMC LO918 Nameplate, Max Speed: 625 rpm Output Flow: 20.2 GPM Measured rpm of 240 rpm. Output flow is equal to 240 rpm/625 rpm X 20.2 GPM = 7.5 GPM.

Sharpening, also known as stripping, is the act of conditioning the bit to regain or improve penetration rate. Sharpening of the bit occurs when sufficient weight is applied to create contact between the supporting matrix and the rock. The friction on the matrix removes it and exposes new diamonds. Sharpening is necessary when a new bit is started, if too low a bit has been selected for the rock type or if an impregnated bit has been allowed to slow down and polish. Active sharpening should be done as little as necessary because it reduces bit life.

Add WOB until torque rises, once penetration rate increases, reduce WOB to maintain desired penetration rate.

Reduce RPM by 1/2, wait until torque and penetration rate rises. Return speed to normal operation.

If 1 and 2 are insufficient (up-holes, underpowered rigs, or too low a series bit), reduce
RPM by 1/2 and reduce water flow. Wait until torque and penetration rate rises. Return
speed and water flow to normal operation.

Large diamond bits have a greater rise in torque on initial sharpening. WOB needs to be held until penetration rate increases. Reduce WOB to maintain desired penetration rate once sharp.

If frequent sharpening is required, a higher series bit formula should be selected. Under no circumstances should any acid be used for sharpening a Boart Longyear impregnated bit. Also, shutting off the water flow while drilling and waiting for the bit to "bite", is not recommended by Boart Longyear as a method of sharpening due to the likelihood of burning in the bit.

On the inaugural episode of the INSITE Podcast I sit down with Bob Corona, Design Engineer – Diamond Products, to talk about how being a chemist is akin to being a chef, why building a relationship with your end users is important, and how learning from your mistakes can be your biggest ally. 

This episode coincides with the recent release of Boart Longyear’s new line of Longyear diamond bits. More information about the diamond bits can be found here.

We would love to hear your questions and comments below. Thank you for listening and be sure to share this episode on LinkedIn, Facebook, or Twitter.