There are many kinds of boring mills. The ones that have a through hole may use support on both ends while there are also another type of boring bar that is only supported in one end. The bar with both ends supported is referred to as line boring. There is another process called back boring wherein the tool will reach through the hole until it is able to bore at the material’s back side. Compared to turning, boring is considered more challenging because the tool is mostly surrounded by the material which limits the design of the tools that can be used. There are also other factors that make boring harder to accomplish such as the decrease in rigidity of the machine in holding the tool, the clearance angle needed is higher which limits the number of support that may be used in the cutting edge and the resulting surface is harder to inspect in terms of its roughness, form and size. Because of the reasons enumerated, boring is considered as a separate machining practice altogether. It can be differentiated from turning because it needs specific expertise, challenge and tips and tricks though there are some resemblance in both processes.
Boring machines are available in various styles and different sizes. Boring can be done on a lathe if the work pieces are just small one but boring mills are required for large ones. The most common diameter of work pieces are from 1 to 4 meters but the large ones can reach up to 20 meters. In order for the method to work, there must be a maximum of 200 horsepower to power up the machines. After the boring, the bores must be cooled down and it is done with the help of the hollow passageway located in the boring bar where there is a good flow for the coolant. In order to prevent too much chatter and vibration while the boring process is ongoing, there are disks made of tungsten-alloy sealed inside the bar. Control systems may also be computer controlled which makes it possible to do things automatically while improving the consistency.
Boring mills can now be controlled with the help of latest technology which is known as CNC. Boring process is done while there are automatic inputs of the different fixed cycles used in order to automatically control the operation. All the subroutines are also preprogrammed which makes it easier to handle the tools.