In the mining industry, line boring is an essential part of machinery upkeep. Every large machine that mine operators depend on, from dozers to excavators, haul trucks to cranes, will require a pin bore refurbishment during its life cycle.

The process involves the use of specialised rotary welders and line boring machines which restore worn or oval pin bores to a perfectly circular shape before this oversized hole is then reclaimed with weld before being machined to OEM specifications.

AMR spoke to line boring specialists, Austin Engineering, about what goes on in the line boring process – both in-house and onsite.

Near and Far

Austin Engineering, founded in 1982 with a national and international reach, offers its customers line boring services alongside a wide array of machining and manufacturing services from its spare parts and machining divisions located in Perth and Mackay.

Line Boring


It also provides onsite line boring services, which means mine operators can save on transportation costs and, more importantly, reduce out of service time for critical equipment.

Austin Engineering’s General manager of Austbore, Mal Kitto, said while several different types of portable boring systems are available, Austin chooses to use the Climax, a widely respected American-made machine. “We just find that it is more efficient than some of the others,” Mr Kitto said.

He said the boring process involved a boring bar, with holes situated along its length for the cutting tips.  This bar passes through the bores to be machined.  Measurements are taken from the old bore centres and any corresponding bores (ie: from the other half of an articulated arm) to determine a new centreline prior to cutting.  Once the operator is certain that all pin bores will be in perfect alignment, the job can commence.

“Attached to the bar is a powerpack that drives a small hydraulic motor, which propels the drive and feed units,” he said. “The drive unit propels the boring bar in a rotary motion, while the feed unit propels the cutting tip through the bores in a straight, linear motion.”

Once the pin bore is enlarged and restored to a perfect circle – eliminating ovality and wear spots within the bore itself – material must be replaced in order to achieve the original manufacturer’s diameter.  This requires the use of specialised rotary welders which gradually deposit weld material inside the bore until its diameter is smaller than the OEM finished size.

Then it is time to re-fit the line borer and machine the bore to its ultimate diameter.

Years of experience and know-how are on hand for any job.

This process can involve multiple cuts, depending on the application, and continues until the exact measurement is achieved.

“The guys are measuring as they go, machining to the final size whether that be the interference fit on a bush, or some sort of fit on a pin. Whatever the requirement is,” Mal said.

This measurement process is achieved with high-tech internal micrometers.

“We have special, specific micrometer arrangements because, as you can imagine, you can’t measure directly through the bore centreline, often times because the bar is still there,” Mal said. “Ordinarily, when measure a bore diameter, you’re measuring again through the centreline of the bore from one side to the other. But if there’s an object in the way, on that centre line (namely the boring bar), you actually can’t do that with conventional internal micrometers. So, we have special micrometer attachments that bridge around that area.

“The difference between the finished internal bore size and the external diameter of the bush to be inserted is typically around 5-thou but it’s application specific. Sometimes it’s more than that.”

Though precise line boring is a specialty of Austin Engineering, the company can also assist in all facets of the refurbishment process. For example, re-fitting of bronze or case-hardened steel bushes.

“It’s often the tail end of the job,” Mal said. “All our onsite units have liquid nitrogen on hand to shrink fit new bushes into the brand new pin bores. And we manufacture those pins and bushes as well at our workshop. That’s part of the spare parts side of our business. We manufacture and refurbish all kinds of parts for all different kinds of earthmoving equipment from dozers through to loaders and trucks. And we also manufacture and repair conveyor pulleys, including the big head and tail pulleys,” Mal commented.

Wait, There’s More

Austin Engineering offers many more engineering services than line boring.

“While line boring is an important side to our business, we’ve grown into a full complement of machining services, component reclamation, the new manufacture of virtually anything,” Mal said.

“That’s the chief competitive advantage of a company that offers the mining industry a vast web of services, effectively distributed across the country,” he said.

“Mine operators don’t need to waste time and money shopping around to a number of different suppliers to fulfill their needs. Because of its off-site capabilities, the kinds of projects that Austin can successfully navigate are manifold. Whether it’s the manufacture of pins and bushes, or the refurbishment and repair of parts for dozers and trucks, Austin can take on all aspects of a complex job and see it to completion.

“We work hand-in-glove across all our divisions on a project” he said.

Spare Parts and Manufacturing

Bill Brumtis, spare parts sales manager at Austin’s spare parts hub in Perth, can attest to the company’s excellence and vast expertise in the spare parts business.

“We’re established, we’re dynamic in terms of spare parts and we’re invested in our clients,” he said.

“We have a full engineering hub in Perth. All the IP is 99% Perth-based,” he said.

Bill notes that the company has an established capacity for in-house machining in Perth. “It’s a big component of our operation here in Perth. We have a number of line boring services out of our workshop here.”

In-house manufactured quality componentscontribute to Austbore’s fast turnaround times.

In addition to this, the Perth office excels in the service and exchange of big-ticket items. Tyre handlers, for example, are a specialty. “We deal a lot with tyre handlers here,” Bill said.

Tyre handlers are considered to be a lifting device and as such require re-certification every ten years. The team in Perth will strip a tyre handler down to pieces, re-test everything thoroughly, and then re-assemble and recertify these mammoth machines with new hoses and new seals, everything that is needed for re-certification and to ensure a prolonged service life.

“And we also do a lot of buckets here,” Bill said. “Refurbishments for buckets. We’re not talking small excavator buckets. We’re talking big machines. EX-8000s, big Hitachi machines. We do everything bucket-wise. From re-builds to new builds.”

“We’ve also got one of the most comprehensive workshops here in Mackay,” Mal said.

“We refurbish most items. And manufacture new components. Typically, we repair a lot of dozer parts, grader components, truck components. That’s all done within our facility. This, and the precision of our line boring capabilities, puts this company out in front of a lot of our competitors. That capability to work as a one-stop solution,” he said.

With its significant investments in the most innovative and up-to-date equipment, the company is well positioned to serve its clients well into the future. Just last year, the company invested in a brand-new CNC horizontal borer.

“It’s a large machine with full tool magazines,” Mal said. “It’s part of the continual upgrade of our fleet.”

This ‘looking-ahead’ frame of mind is matched to a philosophy that puts the customer before all else.

“We’ve got our fingers in a few pies, and that’s what it’s always been about for us – really looking after our clients,” Mal said. “Our clients come to us with a problem, and we say, ‘okay, what can we do to help you out?’”


Austin’s philosophy of service stems from the roots and history of the company. Austin was founded in Brisbane in 1982 and over the years has expanded its reach and expertise through a series of strategic acquisitions, including Austbore, the original home for the Mackay machining workshop, in 2007.

Though now listed on the ASX under the ticker symbol ANG, and though the company is spread far and wide with offices located in Indonesia, the USA and South America, it has maintained its foundational family-business ethics.

“Having come from a family business environment, the customer is king. It was always the Austbore way – how can we help people? I like to think that same attitude and philosophy is carried through,” Mal said.

Indeed, these values of service, commitment and expertise haven’t been lost from generation to generation. The company retains its staff for many years, and it is their knowledge, experience and way of taking care of customers that gets passed on to a newer generation.

“The knowledge and know-how of the people who are doing the training and mentoring of the younger personnel who are coming through – that tradition and knowledge is being passed on,” he said.

For decades, Austin has served mining interests in this country and around the world with dedication and care. It is heartening to know that this quality and range of service will be available for decades to come.

Austin Engineering
Mackay Office: + 61 07 4952 6222
Perth Office: + 61 08 9334 0666