The world of CNC machining calls for an unending pursuit of perfection, where having the right feeds and speeds is a determining factor for unsurpassed quality. Among the different materials we deal with, brass stands out due to its ease of machining and excellent finish. This article delves into the intricacies of optimized Brass CNC feeds and speeds.
Understanding Brass CNC feeds and speeds
When it comes to CNC machining, the "feed" refers to the speed at which the cutter progresses through the material, usually measured in inches per minute (IPM). The "speed," on the other hand, is the speed at which the cutting tool spins, typically measured in revolutions per minute (RPM).
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Fig 1: Brass CNC
Why Brass?
Brass, a copper and zinc alloy, is known for its appealing color, superior corrosion resistance, and excellent machinability. It permits higher feeds and speeds, letting operators increase throughput without sacrificing quality. So, how do you work out the correct brass CNC feeds and speeds?
Selection Criteria for CNC Brass Feeds and Speeds
The ease of working with brass depends on machine stability, tool rigidity, and cut depth and width. Here are some tenets that will help you hit the perfect cutting parameters:
1. RPM:Compute the tool's optimum speed i.e., RPM = (SFPM x 3.82) / D. SFPM is Surface Feed per Minute and 'D' is tool diameter.
2. Feed Rate:Upon obtaining RPM, compute the Feed Rate. If IPM = chip load x number of flutes x RPM, you can effortlessly derive the chip load.
3.Select high-quality, powerful tools having a high helix angle and variable helix or pitch.
4. Employ climb milling as much as possible to boost tool life.
5. Spotting and peck drilling are favored for improved tool life and part finish.
The Magic Numbers
Brass is easy to machine at high speeds without a significant tool wear rate. The ideal SFPM for brass is usually between 200 and 300, with chip loads ranging from 0.001 to 0.01 inches per flute.
For example, if you're using a quarter-inch, four-flute end mill to machine brass, your starting SFPM might be 250, offering an RPM of 3,820 and a feed rate of approximately 15.28 IPM. Note that these are only starting points and may require further adjustment based on machine capabilities and tool quality.
The Role of Coolants
Cutting brass is generally a dry operation. Forcing coolants or lubricants into the process can create dangerous situations, as brass chips are hot and can catch fire when in contact with fluid. However, in high speed and deep cutting operations, use of compressed air can help clear the chips and slightly cool the cutter.
Case Study: Optimizing a Brass Machining Operation
Let us draw from a real-world example to bring these principles home. Machining company X needed to improve their throughput while cutting Brass C360. Armed with a 4-flute carbide end mill running at a speed of 300 SFM and a feed of 0.002" IPT, the results were satisfactory, but output was not optimal.
After a deep evaluation, they took the helix angle from 35 degrees to 45 to improve chip evacuation. They also moved to climb milling, and their SFPM to 400. With the improved tool path and an increased feed to 0.003 IPT, they achieved better surface finish, faster job completion, and tool longevity.
Journey to Perfection
Tweaking CNC feeds and speeds only makes sense when it leads to better part quality, reduced cycle times, and improved tool life. Therefore, nailing the correct brass CNC feeds and speeds is your ticket to these benefits. Remember, parameters such as tool design, brass type, and machine rigidity also play a significant role in operating the brass CNC feeds and speeds.
Though it is a journey to get the perfect combination, these insights will guide you to improve your overall brass CNC drilling and milling productivity, setting you on the right path to continually produce unsurpassed quality work.
Happy Machining!
brass cnc feeds and speeds
