Finish boring completes an existing hole producing a close hole tolerance, correct positioning, and a high-quality surface finish. Generally, it is used with small cutting depths below 0.5 mm (0.020 inch). In contrast, a straight cut in the initial hole when using a rough boring tool does not matter, it will bore true because of its forces are axial. Finish boring tools will likely follow a set path and a longer hole makes it easier for the tool to bend during cutting. Take extra caution to be sure a long hole is true before the finish pass.

Finish boring work within an existing hole to produce a tight hole tolerance, proper positioning, and a high-quality surface finish. It can be an exacting operation where one inaccurate hole can ruin the part. To avoid this result, the drilled hole needs to be prepped by the rough boring process before finish boring takes place. Rough boring removes and prepares the hole for finishing using pre-machining, casting, or forging. The material stock also is a factor whether rough finishing will be needed. Depending on the stock allowance, the use of a rough boring tool could be recommended to avoid multiple finish passes with the finish boring tool.

With a horizontal boring mill or a vertical boring mill machine available, when would you need a boring mill machine? Let’s consider the reasons.

Large Parts

When you have very large workpieces, a boring mill is exactly the machine you need. With its larger configurable space, a boring mill can mount larger workpieces than a horizontal milling machine.

The boring process takes place after other hole making operations, such as drilling or reaming, make the initial hole. Using the existing pre-drilled hole, boring produces more accurate size holes to meet the specific tolerance specifications. Because of the exacting requirements of the boring process, operators should adhere to the following best practices.

When operating a boring bar excessive machining vibrations or chatter can occur because of several issues. To assure you’re maximizing efficiency and producing the best quality part finish, you must avoid basic mistakes that could be causing tool chatter in the boring process. In this blog we will discuss several tips to reduce and eliminate tool chatter.

Dull Cutters

When using a dull cutting tool, chatter will occur because the cutting force necessary is greater. The more a cutter is in operation, the more it will have galling or built-up edge (BUE). To avoid this problem, inspect your tool before operation to determine it has a a sharp cutting edge and fits your exact application.

Incorrect Speeds & Feeds

Using too high of a chip load in the boring process causes deflection, which increases the chances of tool failure. A chip load that is too low causes the tool to bounce off the material because it doesn’t allow the tool to cut enough. Both errors cause chatter and poor quality. It is critical to use the speeds and feeds recommended for the tool when running a boring bar.

No Workpiece Support

Poor or no support on the workpiece in the boring application will result in chatter. Be certain the correct workholding device is solidly set in place to ensure your setup is as rigid as possible. Secure tool holding is also essential for the proper boring performance.

Poor Starter Hole

Beginning a boring project by drilling a proper starter hole ensures the boring bar has sufficient contact with the workpiece for a stabilized cut. The boring bar could deflect off the workpiece if the starter hole is too large and will not have enough clearance if the hole is too small, leading to tool wear and eventual failure. The two critical dimensions to consider when selecting a drill to prepare the workpiece are the head width and minimum bore diameter.

Universal DeVlieg provides innovative and cost-cutting tool holding and high precision boring solutions to the machine tool industry, servicing a diversified customer base. The combination of over 32,000 active part numbers, over 10,000 standard items, and our technical support staff deliver design engineering expertise that is unmatched in the industry. To learn more about Universal DeVlieg, contact us This email address is being protected from spambots. You need JavaScript enabled to view it. or 877.308.3077 or visit at universaldevlieg.com. 

While the process of boring enlarges generally pre-drilled holes, there are several machines that can accomplish this operation. In this blog, we will review the most common types of boring machines.