The term line boring is thrown around in the machining industry often, but not everyone is familiar with this common practice. Line boring is necessary for several machining projects and repairs and can range from simple procedures to complex situations requiring months of work and the input of many engineers.

Line Boring

What is Line Boring?

Line boring is essentially enlarging a hole that has already been cast, making the centerlines of two or more bores collinear. Collinear bores appear in several large machine parts such as engine blocks, gearboxes, presses and turbines. Precision is important in these machines, which is why line boring is commonly used to repair worn bores and their neighbors.

If bores in machining parts are not collinear, it can introduce misalignment, vibration, and even malfunction in a system. Oftentimes a machine will simply not work if even a small amount of misalignment is introduced. This is what makes this type of repair so common.

Line Boring Machines

Our line boring and coupling equipment supports boring diameters from 1.25 inches to 80 inches, with power options like electric, hydraulic, and pneumatic.

How Long Does Line Boring Take?

A line boring job often depends on the complexity of the machine, the number of bores, and how damaged or worn a bore may be. Sometimes, simple repairs can be completed onsite in a few hours. However, there are many cases in which engineering layouts must be obtained, as well as custom boring bar systems. These larger projects can take multiple technicians and sometimes months to complete.

What is Line Boring?

Custom Boring Bars

Boring bars are used to secure the single-point cutters that enter into an existing bore and widen it. They allow the cutter to be moved on an X or Y-Axis to shape the hole, slot, or shaft according to the desired specifications. CEO Machining has a range of 2”-12” Boring bars that can be fitted with a variety of attachments at the ready for most standard jobs.

One size does not always fit all. There are many instances in which on-site machining repairs and boring require irregular boring bars. That is to say, the job cannot be completed by a standard size of the boring bar. This often may have something to do with the design of the machine, nearby obstructions, or limited space. When this occurs, technicians will craft custom boring bars fitted to the desired measurements and capabilities of the job.

When Regular Line Boring Won’t Work

Original bores commonly become worn or damaged after years of operation, even if the machine is kept in working order. Like a tune-up on any machine, parts must be repaired or replaced after long periods of use. This is especially true of foundational parts of the machine, such as bores.

However, just widening the bores to match a damaged or worn hole doesn’t always work. Line boring also occurs when a machine’s bores must be restored to their original centerlines, or the machine won’t work properly. When this happens, engineers will create repair sleeves to fit into the bore rather than attempting to widen the other bores to match the damaged bore.

Line Boring Techniques

What to Expect From a Line Boring Job

While the process may change slightly depending on the needs of the job and the complexity of the machine, you can expect a similar structure for each job.

First, engineers will survey any space constraints at a job site. Ways around obstructions will have to be found, and boring equipment will have to be sized specifically to space. This is usually the stage in which the need for custom boring bars and other pieces, such as repair sleeves, is discovered.

Engineers will then examine the bores to determine the scope of repairs needed. Using a variety of tools like micrometers, indicators, and a visual inspection the engineers will measure the roundness and concentricity of the bores.

Finally, the machining equipment will be installed, aligned, and made ready for operation. Bores will be repaired whether by line boring methods or installing repair sleeves. After the actual repair is complete, engineers will once again inspect for accuracy and that the job specifications have been met.

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