Wednesday, August 29, 2012

Our Philosophy on End Mills: Geometry

Take a close look at our end mills... under a microscope. What you will find is that they look much different than most all of our competitors. 

Edge Strength
Edge Strength: Eccentric relief between primary & secondary
There are numerous variables that have an impact of cutting tool performance and tool life. We designed the tools to be used in different conditions and different machines. We spent many years perfecting the length of the primary and secondary grind in combination with the eccentric relief on our tools. The Red arrow shows the direction of typical cutting tool forces. We’ve believe that we've engineered more edge strength into our tools than any other competitor on the market which means that you can run at higher chip loads.
Double Variable Helix
Double Variable Helix
Chatter has been a persistent problem in milling for many years. Typically most shops will reduce the RPM and/or Feed to reduce the amount of chatter. Chatter is a result of natural harmonics built within the tool which is operating at it's own natural frequency.  Because traditional end mills maintained a consistent helix angle along the length of the flute, the tools tended to get in "tune". Technically, called a Frequency Response Function (FRF).  

Unequal Flute Spacing on a Raptor 3/6
The Double Variable Helix design corrects for this problem with a number of  design elements which enable out tools to run at higher RPM chatter free:
  • Variable Flute Spacing - Each flute is unequally spaced around the circumference of the end mill, creating an out-of-phase cutting action.
  • Double Variable Helix - DVH - The helix angle changes along the cutting edge which further creates an out-of-phase cutting action. 

Heat kills
With the exception of hard milling, it's pretty common knowledge that the heat should be removed with the chip and the less heat transferred to the tool the longer the tool life.  

We've taken a look at that very carefully and have designed our tools to form chips a bit differently.  Chips are formed in the outer rake face of the tools. Instead of the chip traveling all the way down into the gullet of the tools, which causes a lot of friction and heat, and then 6' & 9' formed against the core diameter, we have designed our tools to take a much heavier chip load that most competitors. 

By taking a heavier chip load the material is forced to turn on itself in the other rake face and eject from the cut without traveling down the entire length of the rake face. Think of it like throwing a tennis ball to a point 10 feet in front of you vs throwing it directly between your feet.

1 comment:

  1. My brother is working on a project for his home. I was talking to him yesterday, and he told me that he needed to buy a helix end mill in order to finish the job. He is going to have to shop around his local tool stores. Hopefully he can find what he needs.