What’s Boring Machining and How Does It Work?

Machining is a very important process in mechanical engineering and manufacturing. With its help, you can reshape an item the way you want. There are different machining processes, such as grinding, drilling, milling and turning, along with boring. However, boring machining has a very important role, because it can help deliver an exceptional result and excellent quality, while conveying a great sense of consistency. Even if boring is not a flashy process, it certainly has its uses, especially when it comes to projects that feature lots of holes.

What Does Boring Machining Mean?

In machining, boring means you are refining or enlarging an existing hole found in the current workpiece. You’re using a single-point cutting tool, or even multiple tools at once, depending on the situation. Those can help remove the material from the internal hole surface. What that does is it allows you to improve the accuracy when it comes to alignment, roundness, but also the surface finish and overall diameter.

You might compare boring machining with drilling, as they sound similar. However, that’s not the case at all. When you’re drilling, you’re creating a hole that doesn’t exist already. The role of boring machining is to help you work on that hole and customize it the way you want. You need to do some drilling first before you performing any boring, which is something to keep in mind.

Boring certainly has its role, because it helps correct and finalize the hole to ensure it’s up to specifications. That being said, with boring machining, you can also correct various imperfections that can arise. Those can include things like uneven diameters or misalignment, things that will happen sometimes during the drilling process. No drilling process will be perfect usually, so boring machining can help achieve your desired results quicker.

What Is The Purpose For Boring Machining?

Boring is very helpful and it can serve a multitude of purposes. It always depends on the use case that you have in mind, but it can be extremely effective in a variety of situations, as you will notice below.

· With boring machining, you are getting a very good precision, since it helps you fine tune the hole to the right dimensions. As mentioned earlier, fine tuning can take time and effort, so implementing that can help a lot more than expected.

· Moreover, boring can help enhance the surface texture, not to mention it can lower the overall roughness, something you need to keep in mind.

· Plus, with boring machining, you can have tight tolerances, something that’s harder to achieve with casting or drilling.

· It can also help you ensure that the hole will fit bearings, bushings or other components tightly and without a problem.

· If there is any misalignment when it comes to the holes, it can help you realign those. That can happen, since holes can sometimes be drilled off center, or they could be drilled at the wrong angle. But with boring machining, you can re-adjust those things, and that will help much more than expected.

How Does The Boring Machining Process Work?

In short, what it does is it removes material found in the internal surface of an existing hole. In order to do that, the machine uses a cutting tool. The setup will either require that cutting tool to be rotated, or there will be a rotating workpiece, thus the cutting tool stays in place. That will differ if you perform the boring process on a boring mill where the tool moves or a lathe where the boring bar rotates.

There are some important, key components that you need to keep in mind here, as follows:

· You have the boring bar, which is a rigid and rather long arm whose role is to hold the cutting tool and then insert it within the hole.

· The cutting tool is made out of ceramic, HSS or carbide, depending on the situation.

· The chuck or spindle is there to hold the tool/workpiece and rotate it accordingly.

· Lastly, we have the feed mechanism. Its role here is to move the workpiece/tool on the path you want. That can be pre-programmed, or you can do it manually. But a feed mechanism is very much necessary.

What Types Of Boring Are There?

You will notice that there are different types of boring machining. Thees will vary based on application, but also the overall orientation. Needless to say, each one has a use case, and it’s important to know that before you opt for a specific solution here.

Back Boring

In the case of back boring machining, you enlarge the hole found in the back of the workpiece. The process uses special tools that help you cut and extend only they are retracted within that part. A lot of the time, back boring is used for things like pipe flanges, as well as valve seats.

Line Boring

If you need to machine multiple bores in a straight line, then line boring is the ideal option to consider here. You will notice that line boring is particularly used for engine blocks, or any machinery where you must align holes. Aside from engine blocks, line boring is used for things like crankshaft tunnels or hydraulic cylinders, among many others.

Vertical Boring

Vertical boring is also called vertical tuning. It has a spindle that’s oriented vertically and the workpiece itself is kept on a rotating table. Generally, vertical boring is necessary for flywheels, large valves, structure components, wheels and large gears. Pretty much any heavy component could benefit from vertical boring, and that’s certainly something to consider.

Horizontal Boring

The difference here is that the spindle is set horizontally. Because of that, it’s more effective to use on large work pieces which would normally be very difficult to rotate. Additionally, the horizontal boring can work on turbine casings, machine bases or large engine blocks, among a variety of other things.

Different Types of Boring Machines

Regardless of what kind of boring operation you want to do, there are different types of machines that can be used here. Each one of them has different requirements and it’s something you need to consider.

· Lathe machines are great for medium and small-sized cylindrical items, and can perform boring when they have a boring bar.

· Jig boring machines are very precise, and they are used to create holes that have a very high tolerance. You’ll particularly find these used in die making and tool making.

· CNC boring machines are designed to help automate the boring process. That means you can have repeatable, yet very precise boring solutions that can be extremely complex. And the fact that you can repeat them is even better.

· Boring mills have vertical or horizontal configurations. They are delivering very high precision, and can be used even in the case of industrial applications.

The Difference Between Reaming, Boring and Drilling

Drilling, reaming and boring might seem very similar as processes. But there are quite a lot of differences, and you can see some of the major ones below:

 Clearly, every process has its own purpose here. Drilling helps create the hole, you can use boring to enlarge that hole, and reaming will help add the final touches to that. It always depends on the type of work you want to do, but the ROI is very good, and it can provide an exceptional return.

Advantages and Limitations for Boring Machining

Advantages

Boring machining can be great for a plethora of use cases. And what’s really good about it is that it can help you complete a project and add in a final touch. Plus, you have other benefits, as follows:

· It delivers great precision, which means you get excellent repeatability and tight tolerances, something that works extremely well.

· Additionally, it’s versatile, you can perform boring machining on a variety of hole sizes and even multiple types of materials.

· If you have misshapen or misaligned holes from casting or drilling, boring will help you solve those.

· You also get adjustable tools for a variety of hole sizes. And the best part is that happens with very few changes, something that can help quite a bit.

· Surface finishes are superior when compared to other methods that help you enlarge material holes.

Limitations

· Due to the way boring machining works, you will have some tool deflection sometimes. That can lead to inaccuracies, since very long boring bars can be subject to bending.

· You’re also limited to the existing hole. The boring machining process doesn’t create new holes, it just works on existing ones.

· Machines and tools for boring machining can be expensive.

· If there’s any vibration during the cutting process, that can end up ruining the finish.

What are the Most Common Applications for Boring Machining?

The great thing to note about boring machining is that it can work extremely well in a multitude of use cases. For example, you can use it in the automotive industry for transmission parts, crankshaft housings or engine block cylinders. Aerospace use cases include aircraft frames, the landing gear components, as well as turbine blades and even the jet engine housing.

For the oil and gas industry, you can find boring machining used in the case of valve bodies, pump casings, as well as pipeline flanges. And yes, it’s great to use in the case of manufacturing equipment, for stuff like hydraulic systems, machine bases, press frames, etc. It’s even great for construction and heavy machinery, since you can use it for structural reinforcements, gearboxes, axle housings and so on.

An important thing to consider when it comes to boring machining is the fact that this process is constantly being worked on. CNC automation offers a major advantage, since it boosts repeatability and it can enhance the boring cycles. Additionally, you will have digital tooling that can help with adjustments and live feedback, among others. Plus, composite tooling and smart tooling are other major trend that we can expect when it comes to boring.

Parameters Required During Boring Machining

You always want your work to be as precise as possible. And that’s the reason why you will notice there are certain parameters that will affect the overall boring process. With that in mind, those include:

· Cutting speed is the speed at which the tool’s cutting edge moves when compared to the workpiece’s surface. It’s measured in feet or meters per minute.

· Coolant use is crucial, because using coolant can help you minimize wear. That’s particularly important in the case of deeper holes. If you need to work on larger holes, you need to have the right amount of coolant available.

· Tool geometry matters as well. In this case, it will influence not only the surface finish, but also chip removal as well, which is extremely important to think about.

· Depth of cut focuses on the material thickness, the material that gets removed during a single pass. You can have multiple passes, if necessary. However, this metric focuses on how thick the material removed is, for a single pass.

· Feed rate shows the distance that the tool advances per each revolution.

· Spindle speed is the rotational speed of your spindle, measured in revolutions per minute.

· Tool material and coating are also important parameters to consider here. Tool materials can be PCD, CNB, Carbide or HSS. When it comes to coatings, popular ones are TiAIN or Tin, among others.

· Bore diameter and length matter, because you can have narrow or deep bores, in which case you require a slower feed and specialized tooling as well.

· Lastly, an important parameter is machine rigidity. That’s important because any deflections or vibrations can easily affect surface finish and the overall tolerance.

Conclusion

It’s clear that boring machining can be very powerful, effective and it can make it easier to add a proper finish to holes. It can be extremely important to use for a variety of machining projects, especially when the drilling process did not work as good as expected. But it’s one of those things that will help you eliminate concerns, while improving the process and adapting it to your requirements. We recommend using boring machining if you’re looking to add an adequate finish to holes, while also re-adjusting any mistakes that you made during the drilling process!