1270 Agricola Drive, Saginaw, Michigan 48604 USA 989.752.3077 | Toll Free: 877.308.3077sales@universaldevlieg.com

1270 Agricola Drive, Saginaw, Michigan 48604 USA

Ph: 989.752.3077 | Toll Free:877.308.3077

sales@universaldevlieg.com

Universal Engineering / Devlieg Microbore

Universal/Devlieg Inc.
Universal Devlieg Blog

Boring heads hold cutters, which are the tools that actually remove material, in position as they rotate to bore holes to the specified diameter. There are several boring head options for boring holes and secondary boring operations that could be applied to that simple operation. Let’s review some of the different ones.

 

The process of machine boring provides many advantages beyond enlarging a previously drilled hole to the required size and finish. When done with a Computer Numerical Control (CNC) machine, the multiple benefits of boring machining include:

A boring project that meets all the specified requirements of enlarging a pre-drilled hole starts with knowing the fundamentals. While experienced machinists are well-versed in these boring basics, the beginning operator will find this six-step checklist helpful.

When boring on milling machines, it is generally more complicated than operations on turning machines, such as a lathe. A lathe moves the boring tool in increments. On the other hand, the boring tool or boring head needs adjustments to produce the correct hole size when performing the operation on a mill. Lathe boring tools can make holes of any size, provided the bar fits into the holes. However, boring heads are limited to a specific range on milling machines. Because the boring bar on a mill must be adjustable to achieve the correct size using an adjustable boring head, the setup can be more complex for the operator. 

When setting up a boring project, the operator has the choice between a carbide or steel boring bar. The question is which one? In this blog we provide information to help make that choice.

 

Steel Boring Bars

The standard steel boring bar has a common length to diameter ratio of 3 to 1. However, an operator can make adjustments to achieve ratios of 4 to 1 or 5 to 1. A length to diameter ratios of 10 to 1 can be attained when using a steel dampened boring bar. A steel bar can be modified while it is more difficult with a carbide boring bar.

 

Carbide Boring Bars

A carbide bar offers diameter ratios up to 6 to 1 with 14 to 1 ratio possible with carbide reinforced dampened bars. While a steel boring bar is somewhat flexible, carbide is extremely rigid, allowing for a much higher stickout with less chatter.  

Any operator that has bored deep holes knows that chatter (vibration) is an ongoing challenge. To overcome this issue, consider a dampened boring bar. Keep in mind that the material of the bar and the length to diameter ratio determines its effectiveness.

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.

 

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