Services · 02
Line boring
A bore that has gone oval is one of the more expensive kinds of wear, because of what it usually takes to fix it.
The bore is in a housing. The housing is bolted into a machine. The machine is in a plant. To re-machine that bore on a lathe, all of it has to come apart, travel to a workshop, and go back together again afterwards — and the strip and rebuild is normally worth more than the machining.
Line boring is the alternative. The boring bar goes to the machine instead of the machine coming to the boring bar.
How it works
A boring bar is set up through the worn bore and aligned to the true centreline of the assembly — not to the worn bore, which no longer has a usable centre. The bar is supported at both ends and driven by a portable motor. A cutting head travels along it and takes the bore back to round and to size.
Where the bore has worn beyond what can be cleaned up, it is bored oversize and a bush is fitted, so that the finished dimension matches the original again and standard pins can be used.
The alignment is the part that matters. Two bores that carry the same pin have to be concentric with each other, or the pin binds and the wear starts again inside a month.
Where it comes up
Excavators, loaders and TLBs — boom, stick and bucket pin bores. These are the classic line boring job. The bore goes oval, the pin knocks, and the play gets worse quickly once it starts.
Why the bore went oval
Worth knowing, because otherwise it happens again. Common causes are a pin that was allowed to run loose for too long, a bearing that failed and spun in its housing, poor lubrication, or an assembly that was out of alignment from the start.
If the underlying cause is not addressed, the new bore wears the same way. When we strip a job we say what we found.
What we need from you
- Where the machine is and whether it can be reached
- The bore size and how much play there is now
- Whether the machine can stand for the duration
- Photographs of the assembly
Send it through and we will quote it.
Enquiry
Send us your part.
Tell us what's broken, worn or needed from scratch. Photos and drawings help. We'll quote it and get back to you.