Two of the most common processes used in the world of metal fabrication are milling and drilling. However, the layperson in Phoenix, AZ may not understand the differences between these processes and the applications for which they’re most likely to be used.
Here’s a quick overview of milling and drilling and how they differ.
The process of milling involves the use of a multi-point rotary cutter to rapidly remove material from a workpiece.
There are two primary categories of milling: face milling and peripheral milling. The former involves cutting flat surfaces into a workpiece along with flat-bottomed cavities, and the feed for this can be either vertical or horizontal. The latter involves cutting deep threads, slots and gear teeth out of the workpiece.
When conducting milling, you can feed the workpiece into the rotary cutter in a couple ways. In a conventional milling process, you would feed the workpiece against the rotation of the cutter. If you have a manual milling machine, this is the process you would use. However, you can also perform climb milling, in which you feed the workpiece in the same direction the cutter is rotating. This is the ideal method for CNC milling.
Milling is usually used as a finishing process for a workpiece that has already been machined, as it helps to bring out further definition of important features of the piece and creates a sort of finishing coat. Any items that need slots, pockets, holes or contours would do well with milling as a secondary phase.
Drilling is exactly what it sounds like: the creation of drilled holes in a workpiece. You can use a drill press or tapping machine for this process, or, in some cases, a milling machine. The process creates chips of waste material, but the shape of the drill bit will help the chips to fall away to keep the workpiece completely clear and free of debris.
In a drilling application, it is best to keep the bit perpendicular to the workpiece so you can reduce leading off or drifting. To get the most precise results out of drilling, it is common to add a center drill operation before drilling begins. However, some drilling applications require angular drilling, which needs special tooling to hold the workpiece in place.
You’ll find a variety of different drill bits that are used for different types of drilling operations. Spotting drills, for example, are short drills that are used for making shallow holes or pilot holes. Screw machine bits are short and meant for making straight, accurate holes without need for spotting. Chucking reamers are used for enlarging holes that have already been drilled to ensure they achieve precise diameters. There are also various techniques that can be used in the drilling process, such as peck drilling, which involves frequent retracting of the drill to clear chips and prevent drifting.
For more information about milling vs. drilling and the differences between the two, contact the metal fabricators in Phoenix, AZ at Metal Pro Inc. today.