A vertical boring mill is a machine used to bore holes in metals, usually iron or steel. They are very similar to a typical milling machine, where the workpiece is kept stationary, and milling tools rotate at high speeds. These tools are very similar to drill bits on a drill press and come in many different shapes and sizes to accommodate a variety of applications. A vertical boring mill, however, primarily uses boring bits to bore holes in metals vertically. Boring mills are typically used for drilling holes, or machining the cylinders of an engine block.
When it comes to drilling holes in certain metal parts, a drill press is sometimes inadequate for the job. This is because some parts are made of thick metal, where longer bores are required. In other circumstances, many holes need to be drilled, resulting in a need for accurate boring. While performing some of these tasks on a drill press is certainly possible, vertical boring mills are often employed for projects with such requirements. Sometimes, when it comes to accurate boring, a Computer Numerical Controlled (CNC) vertical boring mill is often necessary for delivering a high-quality product.
Another common use for vertical boring mills is honing the cylinders of an engine. Honing is a process where any imperfections from the inner walls of a cylinder are removed by a high-speed tool. After many years of service, most engines need to be rebuilt or replaced entirely. One of the biggest problems found in many worn engines is wear to the cylinder walls, which results from wear created by the fast reciprocating motion of the pistons, along with small deposits left from lubricating oil. Vertical mills repair the cylinder walls by taking off a very small layer of metal, which removes any imperfections and gives the walls a new surface.
Cylinder boring can also take other forms, where a repair isn't as simple as refacing the cylinder walls. Sometimes, one cylinder in an engine block will be damaged beyond repair, and a replacement of the cylinder wall is necessary. Instead of replacing the entire cylinder block, a vertical boring mill can bore away the damaged wall. After this, a new cast iron sleeve is fitted into the newly bored hole, creating an entirely new cylinder wall.
While it is a frequently performed process, a vertical boring mill can perform many other tasks besides cylinder honing. Some of these include drilling holes in a certain sequence for a part or refacing the inside of a bearing. Boring mills can also create or repair many other parts found in engines, making it a very useful tool for machine shops.