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CNC machining can be a complicated and expensive business, as the effectiveness of any given machining process relies upon each and every tool working as programmed. As a result, it is imperative to keep everything in tip-top shape, replacing any broken or otherwise malfunctioning tools in the system.
This certainly includes carbide end mills, which must be sharp to be suitable for optimal performance. But what are your options when an end mill begins to dull and therefore loses a good deal of its effectiveness? And what can you do in advance to delay that process for as long as possible?
CNC machining can be complicated and expensive. Here are some tips on how to get the most out of your existing tooling.
First, here are a few ways in which end mill tool life can be extended so as to minimize the situation described above.
To get the most out of your end mills, make sure to use the right speed and feed rate. Setting the machining speed too fast or too slow may impede performance and result in an incorrect chip size, poor finish, or general early tool failure. It is also worthwhile to minimize the length of cut (LOC) to only as long as necessary. This is because a tool becomes more susceptible to deflection as its LOC becomes longer, increasing the chance of fracture and thereby decreasing expected tool life.
Using an appropriate coating is also an effective way to extend tool life. Although quality coatings do come along with increased costs, selecting a coating that matches materials and intended performance can vastly boost tool performance. Titanium Aluminum Nitride (TiAlN) and Aluminum Chromium Nitrite (ALCrN) are arguably the two most popular options for use with carbide end mills on the market today.
Finally, make sure you choose the right flute count for your end mills based upon your intended application. There is a tradeoff between flute valleys and core size, with a higher flute count correlating with smaller flute valleys and consequently a larger core. Lower flute counts are usually superior when used with aluminum or non-ferrous materials. Low flute counts help to reduce material chipping, while higher flute counts provide increased strength in cutting ferrous material, which tend to yield smaller chips anyway.
End mills must be sharp to be effective, but those looking to save on cost without sacrificing quality can have their existing end mills resharpened.
With all that said, no tooling component can last forever. Even those who take the best possible care of their tools will still face a situation where some end mills are no longer sharp enough to be effective in metalworking.
Your first instinct may be to buy an entirely new tool to serve as a replacement. Carbide tooling can be expensive, however, making that a costly default position to take. For those open to alternatives, resharpening old tooling is a way to save money while restoring its original operational functionality.
Cost savings can be considerable, with resharpening potentially amounting to between 50% to 90% the cost of a new tool. On average, most tools can be resharpened 3-5 times. Such substantial decreases in per unit cost come without a corresponding sacrifice in quality, naturally resulting in a higher profit margin for the entirety of a given CNC machining process.
Keep in mind, however, that it is important to resharpen a tool before its cutting edge is totally worn and ineffective. Otherwise, it may not be possible to fully restore its performance capacity and the costs of resharpening may exceed the benefits. Therefore, it is worthwhile to develop a resharpening schedule well in advance of the expected end of a tool’s life to send it for regrinding at the optimum time, minimizing downtime and the chance for complete tool failure.