When it comes to choosing excavator bucket teeth, one size doesn’t fit all. Ground conditions, blasting methods and operator technique vary from mine to mine, and optimal tooth choice depends on a good understanding of site characteristics. (Photo: CR Mining)

The current generation of mining shovels and excavators offer increased power, speed and reliability, but they need the right attachments at the tip of the bucket to maintain digging productivity 

By Russell A. Carter, Contributing Editor

Ground engaging tools (GET) are literally the tip of the spear in the ongoing campaign by mines to move more material per shift, and their selection and usage is key to solving the either/or challenge confronting most mine operators: Either pay now, in terms of money, study and upkeep, to install and maintain GET systems that are appropriate for the specific application or pay later after taking a chance that inattention, incorrect configurations or cheaper GET selection won’t result in higher costs from premature bucket wear, stress damage to bucket or attachment components and other related factors.

Given the expense associated with bucket repair or replacement, a decision to find and use GET products that can bolster digging performance while providing adequate bucket protection seems like an obvious choice, but the best solution isn’t always easy to pinpoint. The array of options involving various tooth, lip and shroud combinations, welded, bolted or hammerless attachment systems, metal composition and treatment, and other technical details can be confusing and sometimes misleading. 

For example, massive bucket teeth with thick wear-metal surfaces might look effective and last longer, but there’s a strong possibility that the extra weight, a sub-optimal tooth profile or even a finicky attachment system could contribute significantly to higher operating costs and shorter machine life from inefficient digging. Under certain conditions, a smaller, thinner tooth with less metal and a worry-free attachment system may wear out faster but provide better digging performance and reduced overall costs throughout its service life. And, particular attention should be paid to the tooth adapter system being used; is it strong enough to stand up to the constant high stress forces imposed by a large excavator digging at full machine power?

There are other factors in play that can affect a mine’s GET-related decisions. Right now, metal demand is strong but operating cost pressures are mounting, experienced workers can be hard to find and recent studies indicate that overall productivity is declining. Grade profiles of existing mineral assets are dropping, so mines need to dig more rock to maintain metal production, 

Under these conditions, GET can be regarded as critical consumables, in the opinion of Casey Springer, Weir ESCO’s senior manager-global mining products. “Supply disruptions have the potential to force equipment to be shut down or operated with over-worn or missing components. Situations like these can lead to decreased productivity, significant increase in equipment downtime and maintenance costs due to damage or wear to structural components on mining buckets,” he explained, and suggested a few ways suppliers and mining companies can work together to mitigate potential supply disruptions, such as:

• GET standardization across a fleet, which can reduce the number of different part numbers that need to be stocked and forecasted, allowing for a single, larger pool of inventory used to support changing consumption rates across multiple pieces of equipment.

• Collaboration with suppliers on optimal component selection, material utilization and maintenance practices to achieve the maximum wear life from GET components.

• Selection of suppliers with a flexible, global network of company-owned foundries so they are better positioned to respond to changes in market demand.

New Roles, New Approaches

A 2021 study conducted by Accenture in collaboration with the World Economic Forum predicts that the impact of future operating scenarios, driven by technology, ESG and geopolitical factors, will radically alter the role profiles of industry workers during the next decade in terms of their skill sets, diversity and motivation from those in the current workforce. Specialized roles such as equipment operators and repetitive tasks such as data processing lend themselves to automation and will likely disappear, leading mine operators to seek new approaches for monitoring, collecting and using GET wear data that offer the best use of a company’s available resources. Solutions will most likely be formulated, to a large measure, by a mine’s decision as to whether a GET maintenance strategy can or should be incorporated into its existing general maintenance plan, or more efficiently handled as a separate item, perhaps by a vendor.

E&MJ asked Quintin Nienaber, general manager-Product Management at CR Mining, to comment on some of the more salient points of GET monitoring and maintenance, and how they can fit into a customized plan.

E&MJ: What are the benefits of a strong GET maintenance program? 

Nienaber: A strong program ensures that you are protecting your digging assets and making sure your machines are performing at their optimum level for productivity. To achieve that, you need a deep understanding of your assets, their capabilities, and the expected service life of all the components. You also need to have a good view on what is happening at any point in time to make smart decisions about when to conduct maintenance. This is usually through visual inspections, preventative maintenance practices, and sometimes it can be reactive.

Because we’re on mine sites every week, recording thousands of data points, we have a strong understanding of how to ensure GET is at its peak condition to deliver outstanding productivity and performance. For example, we know that when a tooth has been digging for X hours and looks a certain way, it’s impacting your productivity levels, and it’s time to change it out.

X-Calibre is our condition monitoring and performance tracking and reporting app. With X-Calibre, our site representatives conduct inspections and enter the data, benchmarked against your specific KPIs. Once the inspection is done, the report is completed on the app and sent, before we even leave site. This means that decision makers in the maintenance teams have the most recent actionable information available to them on the day of the inspection.  At the end of the day, it’s about having the information available that enables you to make smart decisions around maintenance.

E&MJ: What’s the one thing that mine operators should know to optimize their maintenance planning programs?

Nienaber: In terms of digging asset (GET and buckets) maintenance, they need to understand the impact that a poorly maintained digging asset can have on productivity and maintenance costs. With GET, sometimes you’re better off changing components out a little earlier rather than later. Once GET passes a certain wear level, your productivity losses could be exponential. 

ESCO mining backhoe bucket with Nemisys lip system.

E&MJ: What common mistakes or missteps do you see in GET maintenance planning?

Nienaber: The false economy of pushing GET wear life to the absolute limit. Using a tooth until it breaks or completely wears out is not saving money. Yes, you get the most out of your $/kg, but the amount of productivity lost because of that worn tooth far outweighs any savings. When people take a very narrow view of trying to make a tooth last as long as possible, they miss the bigger picture. The real question is: how can I make my machines as productive as possible? And the answer is never to keep using worn GET.

E&MJ: In what ways has X-Calibre enhanced maintenance planning by your customers?

Nienaber: X-Calibre allows our site reps to quickly, easily, and accurately inspect machines and give our customers actionable information in the same format every time. Those reports are almost real-time. Because it’s on a mobile device, a site rep can send a report as soon as they’ve finished inspecting, giving sites operationally actional information on the same day of the inspection. Real-time reporting matters because sites need to move quickly on some maintenance decisions. Since the reporting is all digital and centrally stored, we can quickly access it for performance analysis, as well.

E&MJ: How is digitalization changing maintenance planning? And how will CR’s products and services be a part of that?

Nienaber: We now live in a world where decision-making is based on information or tools that are digital in some way. We’re taking significant strides to connect our various technologies so that customers can always know how they are performing in comparison to KPIs and how every decision impacts that performance. By connecting the dots between everything that affects productivity, we’re able to give tailored advice that’s condition specific.

Caterpillar’s BOHA (bolt-on, half-arrow) GET system for underground loaders eliminates the need to weld cutting-edge replacements into place and can last up to two times longer than weld-on options, according to the company.

The real strength of X-Calibre lies in the meeting of digital and on-site experience. Our team are on site weekly, so we’re able to combine that domain expertise with data from X-Calibre to give you a solid foundation for making maintenance decisions around GET and buckets. The vision we are working towards here is to completely take the guesswork out of maintenance. By combining our various technologies like Titan 3330, GET Trakka, Orion Data Analytics, and X-Calibre you will be able to get live condition reporting that’s automated, enabling you to make smarter, faster, and more confident decisions around maintenance activities.

Understanding Diggability

A common thread among all the GET suppliers E&MJ interviewed is that their customers need to thoroughly understand the diggability of the material they’re mining and how its characteristics, in combination with machine capability and operator behavior, can strongly influence GET selection and performance. For example, operators at one site might consistently use an aggressive digging angle to achieve desired muckpile penetration, while those at another site employ a more conservative digging style to get adequate bucket fill. In the latter case, tooth wear over time would likely be even and predictable, while in the former, the teeth will wear prematurely on the top side. 

Most GET suppliers recognize the need to provide practical solutions for mining customers with specific digging requirements and localized problems such as this, and consequently mine operators can choose from a wide selection of systems and specialized components. To counter the particular problem mentioned above, for example, Spanish GET supplier MTG recently introduced their RSU tooth, designed for applications with an aggressive digging angle. Compared with their RSX profile, the RSU tooth profile has a reinforced upper surface with 7.5% more wear material while keeping the same length. This, according to the company, offers better wear performance and durability while providing good penetration throughout the tooth’s service life.

A key to success in proper GET selection, according to ESCO’s Casey Springer, is cooperation between supplier and customer. “Close collaboration between suppliers and mining companies can be mutually beneficial for both parties. End users can benefit from the supplier’s expertise in component selection, assistance with product training, use and maintenance of GET,” said Springer.  “This can result in safer use, reduced maintenance and improved efficiencies of GET components. Receiving feedback from end users on GET performance, ease of use and maintenance can also be invaluable to suppliers. Input can benefit current product optimization as well as to identify pain points to address in next generation system development.

“Achieving optional performance and meeting mine site goals can results from mine operators choosing to partner with a supplier with a broad product offering and one that is willing to customize configurations to meet specific requirement,” he continued, using as an example ESCO’s Nemisys GET system offerings for a Hitachi EX5600 hydraulic excavator. “In extreme applications, the N5 nose size would be a good choice, with a wealth of options available to the operation to deliver optimal performance. In addition, XHD intermediate adapters and shrouds combined with a heavy duty point will deliver the best system reliability, wear life and lip maintenance. This option also features extended bottom wear shoes to provide additional protection for the structural members on the underside of the cast lip to further decrease maintenance and extend lip life,” he explained.

“For less demanding conditions, the ESCO Nemisys N5 V2 lip, which allows for smaller, lighter Nemisys N3 points and shrouds, can be used without sacrificing nose strength on the cast lip. This option saves more than 3,500 pounds over the XHD configuration, potentially increasing the functional payload of the bucket or freeing up weight that could then be reallocated to enhancing the wear package in high wear areas on the bucket.”

Springer went on to point out that throughout the industry, the right choice of mining bucket lip systems and GET can have a significant impact on machine and fleet level productivity and efficiency, and this is especially true for cable shovels. “For larger cable shovels, the market has primarily implemented Whisler-style lips with mechanically attached adapters but an increasing number of customers are now considering integral nose cast lip options similar to those used on large (greater than 350 tons) hydraulic excavators,” said Springer. “For mining operations where an integral nose cast lip is a viable option, the more streamlined system profile provides both weight and system dig energy reductions. Combining lip and GET selection with optimized bucket designs can deliver improved bucket fill factors and pass matching which increase overall fleet production and efficiency.

“Opting for a Nemisys integral nose cast lip also affords customers the ability to standardize their GET across both their cable shovel and large hydraulic excavator fleets,” he noted. “This can significantly reduce the number of different parts that need to be stocked and managed and simplifies training and tool requirements to support GET maintenance and change-outs.”

There are also significant safety concerns associated with GET selection, said Springer. “ESCO has continued to invest in optimizing and refining its locking and retention technologies. For example, the Nemisys safety lock was recently upgraded to include top and bottom O-ring seals which help insure safe, easy removal even in environments with heavy fines, excessive moisture, or other factors that can affect component removal.”

Vendors Expand GET Products, Services

Spending a seven-figure sum on a new mining-class excavator that can load 60-ton bucketfuls per pass might understandably divert a mine’s attention from consumable items such as GET that may only be hundreds or a few thousands of dollars per item or assembly, but the costs can add up in a hurry — tooth wear, for instance, can be surprisingly rapid. A recent study at a European surface mine showed the middle teeth on the mine’s shovel buckets lost 40% of their original weight due to wear over 117 operating hours, while another large open-pit copper operation in the U.S. reported a need to change out its large rope-shovel bucket teeth on average every four days. Worldwide, the market for GET is expected to be in the greater-than $1.5-billion range by 2024, and suppliers are enhancing their production capabilities and product offerings.

A few examples: Late in 2021, MTG announced that it will spend 12-million at its foundry in Monzón, Spain, to increase production capacity, flexibility, digitalization, and energy efficiency. Construction will be carried out over the next 3-4 years and the project will increase total production capacity by 50% and foundry size by more than 30%. And, as mentioned in a recent issue (see Building a Better Maintenance Plan, p. 34, E&MJ, February 2022), Caterpillar is expanding its portfolio of Customer Value Agreements (CVAs), a selectable package of support and maintenance agreements that can be tailored to meet specific customer needs. Among the new offerings are GET/Bucket CVAs that can include complete bucket rebuilds, inventory management, on-site dealer inspections with reports, removal and installation services and more.

Cat also has a large inventory of GET solutions ranging from complete systems down to a variety of specialized, individual wear components. It recently introduced the BOHA (bolt-on, half-arrow) GET design for underground loaders (see GET-ting to the Point, pp. 24-29, E&MJ, March 2021). The company noted that its main benefit to underground operations is elimination of the need to weld cutting-edge replacements into place. An average weld-on set of cutting edges can take 20-40 hours to replace. BOHA takes approximately 1 to 2 hours to replace and requires no welding. Plus, during extensive field trials prior to introduction, Cat matched BOHA GET against weld-on systems and found that in some cases, BOHA provided twice the life of weld-on options.

Cat offers wear components including chocky bars, buttons in a range of sizes and shapes, roll bars, wear lugs, bolt protectors and others in both manganese and laminated metal compositions. The latter product line includes 6 x 8-in. wear blocks that feature a zigzag inset design which allows for material-on-material wear. According to Cat, they prevent channel wear common in parallel grooves, delivering extended life in extreme operations. Also available are 3 x 4-in. wear patch blocks that can be plug welded in tight areas, and can also be grouped together where no gaps are desired between parts. Cat also carries 11-in. trapezoidal wear blocks that can fill a tapered area or be staggered in a pattern to avoid straight-line channels, and also feature a zigzag inset design.

Australia-based wear parts supplier Bradken recently called attention to its line of Eclipse cast lip GET systems, showcasing a 5.5-m (18-ft) wide unit that weighs 13,200 kg (29,100 lb) with all tools attached, that had been installed a year ago on a hydraulic face shovel working at a gold mine in Western Australia. Bradken said the customer has benefitted from a range of design features, including:

• Fast, safe GET changeouts with hammerless installation and removal.

• Up to 3% reduction in fill power leading to improved penetration and lower fuel burn. 

• The optimized nose angle has increased cutting clearance and toe access to reduce fill energy. 

• A 1-metric-ton mass reduction over the previous generation lip.

• Predicted increase in fatigue life of up to 50%.

Overall, the company said, the broad benefits of applying the Eclipse cast lip range from improved bucket fill performance and reduced cycle times, to extended maintenance intervals.

Those advantages apply to well-engineered cast-lip systems in general, according to CR Mining, which notes that this type of system, originally used mostly on excavators in the 400-ton class and above, now can offer the same design benefits for smaller machines (100-400 ton) as well as wheel loaders. Excavator performance improvements gained by installing cast-lip systems are generally in the low to middle single-digit range, but with the size of machines typically used in mining, those seemingly modest increases can provide significant results. For example, CR Mining said conversion of a sub-400 ton excavator to a cast lip GET system eliminates the need for weld-on components, resulting in 90% less maintenance and reducing GET overhaul costs by a third or more.

And on larger excavators, small improvements in cycle time gained through more efficient digging with optimal GET lip and tooth profile shape and plane alignment can amount to large increases in productivity. According to the company, reducing a 700-ton excavator’s cycle time by one second can improve the machine’s productivity by 1% and add another 250,000 tons to its yearly output. Increase bucket fill by 1 m3 and get 5% more productivity which, on the same size machine, would result in 600,000 more tons per year.

Minimizing GET Loss and Damage

Apart from the loss of digging efficiency caused by GET breakage and loss, these incidents require ongoing attention from operators in order to avoid unexpected, and expensive, machine downtime due to unscheduled changeout of bucket teeth or downstream damage/delay at the crusher because of broken tooth fragments in the feed. As is the case with many other mining applications, Artificial Intelligence (AI) has an expanding role in the solutions available to mines for monitoring and tracking GET components.

One example is Canada-based Motion Metrics, now part of the Weir Group, which recently reported that it had delivered 16 ShovelMetrics Gen 3 systems to a large iron ore mine in South America. The machine vision-based system employs high-resolution rugged cameras and 3D display of the bucket, supported by an advanced AI algorithm to monitor and alert operators to missing teeth and lip shroud problems, along with 3D particle size sensing and boulder detection. The company said ShovelMetrics interfaces with its centralized data analysis platform, MetricsManager Pro. Authorized users can receive automated SMS and email missing tooth notifications, view equipment activity logs and monitor tooth wear to schedule maintenance.

At another mine in the nearby Coquimbo region of Chile, Motion Metrics said its LoaderMetrics solution for wheel loaders has helped to prevent significant production loss from tooth breakage each year. Over the course of a year, the mine detected 12 missing loader teeth and experienced zero crusher downtime, preventing an estimated $1.25 million annual production loss that the mine would have experienced prior to installing a missing tooth detection system.