Line Boring Services for Simple and Complex Machining

Line boring is a machining process that repairs various equipment parts so they don’t need to be replaced. Line boring can repair out-of-specification or damaged bushing inserts, pin fits, and barrels applicable to a wide range of equipment, including:

• Cranes
• Hydraulic cylinders
• Excavators
• Material handlers
• And more

There are several reasons why a manufacturing, mechanical, or engineering project would require line boring services. Minute adjustments to parts and workpieces will always be required where precise work is produced using special tools. Many machines in these industries will stop working if even a small amount of misalignment occurs. Misalignment, malfunction, and vibration are all common symptoms of non-collinear bores in machining parts, making line boring a common type of repair.

Line boring is essentially the process of enlarging an existing hole to make the center lines of two or more bores collinear. Collinear bores are essential for the proper operation of many large machine parts, including engine blocks, turbines, gearboxes, presses, and more.

Line boring is a crucial task that requires a combination of the right talent and equipment. Line boring is required for simple applications in most situations but can be very complex in others. The most complex jobs – especially ones requiring custom solutions – need a certain skill level to be carried out correctly. The most complex jobs can require many engineers and months of work.

Types of Boring Machines

Line boring machines are designed to enlarge the diameter of a hole that’s already in place. While these machines are generally used to cut into the component where the hole exists, the use of each is very specific. There are numerous tools that can be used within the machine with a line boring head to create various outcomes. The right types of tools and machines are required to produce precise and accurate finished products.

Line Boring Machine

A line boring machine is a device that uses a bore to enlarge existing holes in a workpiece to produce smooth and accurate holes. It achieves this with either a small grinding wheel or a single cutting tip that’s made of cemented carbide, steel, or diamond. No matter what the tip is made of, it’s an economical piece of equipment that’s strong enough to bore holes in heavy construction equipment, including cranes and end loaders. Some line boring machines use a facing head to cut tapered holes or machine a workpiece surface.

Carpenter’s Boring Machine

A carpenter’s boring machine is a specialized hand-driven piece of equipment that’s used to bore holes in beams. Some of the most common applications for this type of boring machine is to make holes for wooden pegs that hold tenon and mortise joints together and in the process of making a mortise.

Single-Point Tool

A single-point tool is a tooling head for a boring machine that’s secured in a rotating spindle or boring bar. It moves in a circular motion against the sides of existing holes to accurately increase the diameter. This movement is controlled by adjusting the boring head of a hydraulic, pneumatic, or electric machine.

Grinding-Wheel Cutters

Grinding-wheel cutters rotate rapidly in a planetary motion on their own axes. The axes rotate slowly with the boring head on a spindle axis. The diameter of the hole can be adjusted and controlled by adjusting the distance between the spindle axis and the wheel axis.

Other Types of Boring Machines Include:

• Coupling boring machines – These specialized machines are designed to bore precision couplings.
• Horizontal boring machines – These time-saving machines are typically used to bore holes in machines and equipment with highly rigid construction types.
• Tunnel boring machines – These powerful machines produce a smooth tunnel wall and are capable of drilling a bore in anything from sand to hard rock.
• Directional boring machines – These multifaceted machines include slideable drive and frame mechanisms mounted on the frame.
• Vertical boring machines – These manual machines are made with a drill chuck and designed for vertical drilling.
• Cylinder boring machines – These specialized machines are used for reboring automobile engine cylinders.
• Jig boring machines – These precise machines are used to enlarge the diameter of existing holes with a high level of accuracy. They’re used to bore, drill, and counter-sink holes in metal workpieces.
• Portable boring machines – These powerful machines are also flexible and easy to use. They’re available with hydraulic or pneumatic drives.

Line Boring Applications

Many businesses require line boring services for various reasons. From shipbuilding to car manufacturing to the power industry and various other industries with complex mechanical requirements, there are many machines and other pieces of equipment that require fine-tuning. Some of the most common line boring applications include:

• Engine bedplates
• Turbine casing
• Driveshaft housing
• Gearbox housings and parts
• Cylinder linear locations
• Clevis plate bores
• Hinge pins
• A-frame supports
• Shipbuilding applications, including stern tubes and rudder parts

There are many reasons for engineers to use line boring machines, all of which depend on the specific sector and type of machinery. In all cases, these machines can ensure workpiece precision to the micrometer.

General Line Boring Services

General line boring services are required for large stationery items that have been damaged or worn and are too difficult or impossible to remove from the site for repair. These services cover components like:

• Engine bedplates
• Rudder stocks
• Compressor casings
• Stern tubes
• Cylinder blocks
• Hinge pin bores
• Pintle bores
• A-frames
• Stator frames
• Coupling holes
• Gas, steam, and hydro turbine casings
• Other major items

General line boring services should only be performed by highly trained and experienced engineers. These professionals are versed in the latest components and repair techniques.

Engine Line Boring Services

Line boring, sometimes referred to as align boring, describes the process of creating accurately aligned, perfectly straight bores in engine machining processes. Line boring is arguably the most crucial step in an engine block’s blueprinting process. It’s used for the crankshaft, camshaft housing, saddles, and tunnels. It’s a cost-effective, time-saving alternative to replacing failed components.

When a crankshaft fails in marine diesel engines and other large generating sets, compressor main bearing bores are often damaged. Replacing these parts can be extremely costly and time-consuming but can be repaired using engine line boring services. Whether the equipment has a conventional bedplate layout or an under-slung configuration, repairs can be carried out by experienced engineers who have access to a range of engine boring equipment and associated optical and laser alignment accessories and tooling.

Experienced engineers work closely with engine manufacturers and business owners to carry out repairs, whether using equipment to complete a series of bores in line or to repair main bearing pocket bores individually. The best engineers will work closely with the engine manufacturers and business owners to come up with a defined plan that conforms with OEM design standards.

Thermal Spraying

Thermal spraying is an ideal option for repairing worn and damaged bearing pockets. In this high-quality boring process, all damage is removed by machining out the bores and spraying them to rebuild the material that was removed.

This process involves heating wire or powder material until it reaches a molten state. Then, a layer is projected onto the receiving component by gas or air. The process is repeated as many times as it takes for the material to build up to the required specification.

Additional Line Boring Repair Methods

When bores require repair, they’re often machined oversized, then sprayed and bored to a standard size. Selective plating and electroplated, though rarely used, are additional applications for repair.

Another common method used to repair damaged bores is sleeving of main bearing journal bores. In this procedure, the bores are machined and secured with radially fitted screws before being machined to their design size. A sight allowance is then left in the sleeve to allow for final machining to a standard size.

Associated repairs and procedures can remove wear and fretting from make-up plating and take the form of advanced metal stitching for bearing cap fit location milling and heat-induced cracking. These repairs and procedures are allied to main bearing bore work.

In such procedures, mating bearing caps can be reused. However, new bearing caps are often advised and may even be provided by the manufacturer. The half bore is left with a diameter allowance for final assembly machining.

What to Expect During a Line Boring Procedure

Since line boring procedures span a wide range of applications and industries, the process can change depending on the nature of the job. Different workpieces have varying complexities and specific uses. Here’s a general idea of the process.

• First, an experienced engineer will review the workpiece, paying close attention to the mounting of the equipment and the repair procedure.
• Next, the engineer may source custom repair sleeves or boring bars if necessary.
• Then, the engineer will consider the scope of the work using precise measuring equipment.
• The engineer will measure the roundness and diameter of the bore.
• Then, the engineer will install and align the equipment.
• After the engineer completes the boring procedure, they will inspect for accuracy.

When the engineer surveys space constraints at a job site, they’ll often need to find ways around obstructions, and line boring equipment will have to be specifically sized to fit the space. This is typically the part of the process in which the need for custom boring bars and other pieces, such as repair sleeves, is discovered. Engineers use a variety of tools, including indicators, micrometers, and a visual inspection, to measure the bores’ roundness and concentricity.

Once the machining equipment is installed, aligned, and cleared as ready for operation, the bores can be repaired by installing repair sleeves or by other line boring methods. Once the repair is complete, rest assured that engineers will inspect for accuracy.

How Long Does the Job Take?

As each line boring job depends on the number of bores, the amount of damage or wear on the bore, the number of bores, and how worn or damaged the bore may be, simple repairs can often be completed onsite within a few hours. However, in more complex cases, engineering layouts and custom boring bar systems must be designed and completed. Such projects can take several engineers and months to complete.

What Happens if Regular Line Boring Doesn’t Work?

Even if machines are well-maintained and kept in working order, it’s common for original bores to become damaged or worn after years of operation. These parts must be replaced or repaired after long periods of use – especially if the foundational parts of the machine (the bores) are damaged or worn.

Sometimes, widening bores to match a worn or damaged hole doesn’t work. In such cases, the machine’s bores need to be restored to their original centerlines. Rather than attempt to widen other bores, engineers achieve this by creating repair sleeves to fit into the bore.

Custom Boring Bars

One size doesn’t always fit all, which is why there are so many types of boring machines and applications. Oftentimes, due to factors like nearby obstructions, the design of the machine, and limited space, on-site boring and machine repairs require irregular boring bars.

Boring bars are designed to secure the cutters that enter into and widen an existing bore. They allow the cutter to be moved to shape the shaft, hole, or slot according to the desired specifications. This allows the cutter to be moved on an X or Y-axis to shape it.

Whether you’re looking for a solution to a simple or complex problem, our experienced engineers can help assess the situation and plan out the best line boring service for your needs. Contact us today to discuss your unique situation and get started on a plan to repair your equipment.

Read more about MWM’s expertise and line boring services. We have a vetted group of sub-contractors and partnerships with various engineering and architectural firms for complete design-build applications.