Before (bottom) and after (top) views of a Sandvik DD420 underground drill
that was recently restored to as-new condition at a Sandvik service center
in Australia.

According to Sandvik Mining, this option requires the facilities, skills and factory support to be able to rebuild equipment to as-new, OEM-compliant standards— starting with equipment that offers the original durability and design to provide the potential for a second life.

A recent example of this, provided by Sandvik Australia, is a seven-year-old Sandvik DD420 development drill, which underwent a major overhaul at Sandvik’s customer service center in Kalgoorlie, Western Australia, returning it to as-new condition, including upgrades to incorporate the most recent components.

Nathan Bradshaw, workshop supervisor at the Kalgoorlie CSC, said the 11-week rebuild process resulted in a machine that can be expected to work productively for a further seven years if it is operated and maintained in line with Sandvik’s recommended maintenance procedures.

The rig, which had been operated in a Western Australian nickel mine for the past seven years, had to be “re-specced” to meet the quite different standards of the Queensland silver mine for which it was being rebuilt.

“The two mine sites had widely varying compliance requirements—both are very rigorous, but both are very different,” said Bradshaw.

As a result of the rebuild, the machine was returned to as-new condition and is covered by warranty. And the silver mine for which it was rebuilt is getting a development drill for around 70% of the cost of a new machine.

The scope of work for the DD420 rebuild involved stripping the rig down to its base chassis and components, replacing specified items, and repairing or replacing other parts and components as necessary to ensure everything was back to OEM-compliant condition (see below for a detailed outline of the scope).

“Following the rebuild, all service, parts and safety bulletins, as well as machine upgrades, will have been completed, so the finished product is as up-to-date as any machine can be—given it is a seven-yearold carrier and drill rig,” said Bradshaw.

“An important element of the success of a project like this is that the durability and quality is built into these Sandvik underground rigs from the beginning, so that we have solid, strong carrier and drilling module to work with, and which have the strength to continue reliably performing for a further seven years,” he said.

Jim Tolley, Sandvik Mining’s Region Australia vice president, said this DD420 rebuild—and others of a similar scope being carried out at Sandvik service centers— were a prime example of how the mining industry is driving more value from suppliers and equipment.

“Just a few years ago, a drill rig of this age would probably have been retired and replaced with a new one,” he said. “Projects such as this one are examples of how we can work with our mining customers to reduce their capital equipment costs, while maintaining or improving their required levels of productivity.”

DD420 Rig Rebuild: Scope of Work
The scope of works for the DD420 rebuild covered both new OEM components as well as repairs to as-new condition, incorporating:
• New powertrain, including new front and rear axle assemblies, engine, transmission, torque converter and driveshafts;
• New wheels, tires, cooling, exhaust and air intake systems;
• Tested and repaired carrier components, including jack-leg cylinders, electric motors and air compressor;
• New carrier components, including water pump, steer cylinders and hydraulic pumps;
• Cabin completely stripped, sandblasted and inspected, repaired as required, replacement glass installed, all carried out according to FOPS certification requirements;
• A complete rewire of the carrier and drilling circuit, along with the replacement of all switches, sensors and senders with genuine Sandvik components;
• Trailing cable replacement;
• Slip ring box and A cabinet completely overhauled;
• Lighting circuit upgraded to LEDs and HIDs as required;
• Dismantling of the drilling module for overhaul, with replacement components including inner tubes, feed rails and feed cradles, while all other major components are overhauled;
• Stripping and assessing of the drifters to return them to OEM specifications;
• Complete machine re-hose; • General panel repairs, structural repairs and painting; • Fitment of a Sandvik 65L FS1000 AS5062-compliant fire suppression system; and
• Supply and fitment of a water wash, two searchlight assemblies, air filtration system and live oil sampling system.