Heavy Mechanical

Line Boring & Bore Welding

Worn pin bores welded up and machined back to size in place, on the boom, the chassis or the bucket.

Overview

What the work involves

Every pin joint on an excavator, loader or dozer wears. The bore goes oval, the pin knocks, the bush spins, and the slop works its way through the whole linkage until the machine loses accuracy and the parent casting starts to crack.

The repair is to put the metal back and cut it true. The bore is welded up to restore material, then a portable boring bar is clamped to the structure itself, aligned to the original centre line and used to machine the bore back to the drawing size. Because the equipment travels to the machine, the boom or chassis does not have to be cut out and freighted to a machine shop.

Work is carried out in our workshop where the component can come in, and on site where it cannot. Paired lugs are bored on one setup so the two bores stay concentric, and new bushes are pressed and measured before the joint is pinned back up.

At a glance

Division: Heavy Mechanical
Availability: Workshop and on site
Method steps: 5
Sectors served: 3
Base: Middelburg

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What you get

What this actually changes for your operation

The machine does not leave site

The boring equipment is portable and clamps to the structure being repaired, so a worn boom is fixed where it stands instead of being cut out and carted to a machine shop.

Metal replaced, not packed out

The bore is welded back up and cut to size. Oversize bushes and weld-and-hope shims move the problem along a few hundred hours; restoring the bore ends it.

Paired lugs bored on one setup

Both sides of a joint are machined from the same alignment, which is what keeps the bores concentric and stops the new pin binding.

Cracking headed off

Slop in a pin joint loads the parent casting in a way it was never designed for. Catching the bore early is cheaper than a structural repair later.

Method

How the work runs, step by step

Every stage has an output you can see. Nothing moves to the next step until the previous one is signed.

01
Measure and assess
Same day
Pin and bore measured, wear pattern recorded and the joint checked for cracking before anything is committed to.
02
Strip and prepare
Per scope
Pin and bush removed, the bore cleaned back to sound metal and the structure supported so nothing moves during the repair.
03
Bore welding
Per scope
Material deposited back into the bore under a controlled pass sequence, building the wall up past finished size.
04
Line boring
Per scope
Boring bar clamped and aligned to the original centre line, then the bore machined back to the drawing dimension and finish.
05
Bush, pin and hand back
Same day
New bush pressed, bore and pin measured against specification, joint reassembled and the recorded sizes handed over.

On the tools

The repair, as it happens

Short clips with no sound. Photographs show what came out the other end; these show the work itself.

The rig, set up and runningThe boring unit clamped to the boom, aligned and cutting. Nothing was removed from the machine to get here.
Bore welding, first passesWeld metal laid into the worn bore under a controlled pass sequence, building the wall back past finished size.
Looking down the boreThe same weld seen from the open end, running an even bead around the full circumference.
Welding head on the boomThe welding head driven by the same unit that will later carry the cutting tool, so the two share one alignment.
Boring bar set to the centre lineThe bar mounted through the joint and trued to the original bore centre before a cut is taken.
Taking the cutSwarf coming off a continuous cut. A clean, unbroken chip is what a correctly fed bore looks like.
Machining back to sizeThe head working through the joint, with the cuttings collecting below the repair.