Milling Tool Technologies for Boring Operations on Machining Centers
Boring operations are used in almost every machine shop to create cylindrical holes in workpieces. To achieve precision results, it requires the correct choice of milling tool and cutting parameters for optimal machining. This article outlines the key cutting tool technologies used for boring operations and the common variables that are involved to produce high-quality results from machining centers.
The traditional tool for boring operations has been the boring bar, which is a single-point turning tool with a negative rake angle on the cutting edge. As the cutting edge gradually wears away due to the cutting action, it will eventually become blunt after several passes. This can cause a significant increase in machining time, as well as an increase in the cutting forces, vibration, and overall surface finish. In recent years, more advanced milling tool technologies have been developed to reduce machining time and improve surface finish.
One of these technologies is the multi-flute tool. This is a single-point tool with cutting edges extending along its length, similar to a drill bit. The added cutting edges result in a more balanced cutting force, which reduces vibration and improves surface finish. Additionally, the multi-flute tool reduces tool wear, as when one cutting edge becomes blunt it can rotate to a fresh cutting surface to continue machining.
Another popular tool for boring operations is the indexable-insert boring tool, which is an indexable cutting tool with replaceable inserts mounted in pockets along the top of the tool. Inserts can be selected for different applications depending on their design, geometry, and the material being machined. The inserts can also be easily replaced when they become worn, resulting in a significant reduction in tool changeover time.
The cutting parameters used for boring operations on machining centers are also important for achieving optimal results. The key parameters are cutting speed, feed rate, and depth of cut. The cutting speed is usually expressed in meters per minute and is typically set to a value that matches the material being machined and the tool being used. The feed rate is affected by the depth of cut and is usually set to a value that will produce the desired surface finish and cutting forces. The depth of cut should be set to a value that will produce the desired result without overloading the cutting tool or workpiece.
Beyond the tool and cutting parameters, the machine should also be set up and calibrated properly. This includes ensuring proper tool changers, spindle speeds, and machine rigidity to prevent vibration and chatter. Additionally, it is important to make sure the tools are properly secured and the coolant is adequate to prevent tool shattering.
In conclusion, boring operations are a common and important operation for machining centers, and there are many cutting tool technologies and variables that must be considered for optimal results. Boring tools such as multi-flute tool and indexable-insert boring tools are becoming more popular and offer significant advantages over traditional boring bars. Additionally, it is important to set up the machine and select the correct cutting speed, feed rate, and depth of cut for the materials being machined. With the correct selection and setup, it is possible to achieve high-quality results from boring operations on machining centers.
