FILENAMES:

micromill.jpg

DESCRIPTION:

This is a picture of very small end mills. Posted by Ed Huntress 
<mike234@bellatlantic.net>. Ed provided the following description:

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Re: micromill.jpg

These are the latest endmills for real high-speed milling, as of 
Feb. '01. Made by Jabro of the Netherlands, they're made to run 
in high-tech machining centers, turning 30,000 - 70,000 rpm. They 
are NOT engraving cutters. They're two-flute ballnose endmills, 
and they cost about a gazillion bucks.

The one on the left is 0.004" (0.1 mm) diameter, TiAlN (titanium 
aluminum nitride) coated. It's made for cutting hardened mold steel 
ranging up to Rc 60 or so. The cutting edges have negative rake. 
Made with a core diameter of 85% of the total diameter, they take 
chips a little under 0.001". They're made of sub-micrograin high-cobalt 
tungsten carbide.

The one on the right is 0.008" (0.2 mm) diameter, positive rake, and 
diamond coated. It's made for cutting graphite EDM electrodes, and 
it has positive rake. The diameter of this cutter is less than the 
average diamond coating thickness on standard tools. Jabro has really 
pushed the coating-technology envelope with this one.

The machines these run on are the latest generation of high-speed, 
high-traverse-rate machining centers, made for moldmaking. They have 
very advanced CNC controls, which are required to keep from breaking 
the tools. Their applications are usually milling of contoured mold 
cavities and cores, using stepovers between passes on the order of 
0.0006" (0.015 mm), producing a finish that is nearly polished. Many 
of these molds are run with no hand polishing at all.

Ed Huntress