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At Destiny Tool we believe that an end mill is only as good as the engineering that is behind it.
We’ve cut our teeth in non-ferrous and hi-temp alloys for many years and we believe that our performance end mills are the very best available in the world for those specific material groups. In our view, there are four major components that make up a performance end mill... |
Download our 2014 catalog as a PDF here:
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• Substrate • Geometry • Tolerance • Coating
Carbide Substrate
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The most commonly used term for carbide is “Micro-Grain” but it does NOT really describe the differences that have evolved since the first development of “Micro-Grain” in the past 40–50 years.
Fine, Ultra-Fine and Sub Micron grains are some of the current terminol- ogy that is used. Two other commonly used terms are “toughness” and “wear resistance.” We’ve found that neither term can be used as a proper gage. Here’s why: |
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Toughness – Fracture toughness is not only a characteristic of the material but also a function of the loading conditions. Carbide rod is measured for “toughness” before geometry has been ground into the tool and a finished, ground tool can vary as much as 300% in “fracture toughness” based upon geometry alone.
Wear Resistance – Cutting tool wear is a result of complicated physical, chemical, and thermo-mechanical actions. Tool wear is caused by such mechanisms as adhesion, abrasion, diffusion & oxidation that all act together with predominant influence of one or more of them in different situations within the CNC machine, which is quite different from lab testing.
Wear Resistance – Cutting tool wear is a result of complicated physical, chemical, and thermo-mechanical actions. Tool wear is caused by such mechanisms as adhesion, abrasion, diffusion & oxidation that all act together with predominant influence of one or more of them in different situations within the CNC machine, which is quite different from lab testing.
End Mill Geometry
Edge Strength
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 we engineered more edge strength into our tools than any other competitor on the market.
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 we engineered more edge strength into our tools than any other competitor on the market.
Double Variable Helix (DVH), Patented
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, it's called a Frequency Response Function (FRF).
The Double Variable Helix design corrects for this problem with a number of design elements which enable our 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.
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, it's called a Frequency Response Function (FRF).
The Double Variable Helix design corrects for this problem with a number of design elements which enable our 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.
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.
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We've taken a look at that very carefully and have designed our tools to form chips a bit differently on our tools. 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’s & 9’s formed against the core diameter, we have designed our tools to take a much heavier chip load that most competitors. |
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By taking a heavier chip load the material is forced to turn on itself in the outer 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.
When we talk about tolerance, we are actually referring to two components of our end mills. Of course our shank diameters are held tighter than standard h6 industry specifications of -0.0001"/ -0.0003." Our Viper and Diamond Back End Mills are held to -0.0001" / - 0.0003" on diameter AND shank. However, that's just part of the story...
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We’ve really concentrated a lot of time on the grinding tolerance as well. When you look at our competitors under a microscope, many times you will see that the primary and secondary grind finish looks like a washboard texture because of the wheel that was used to grind it with.
End Mill performance in high speed machining is dependent upon the surface roughness (topography) of the rake face and and relief face of the end mill. Better, smoother ground surfaces reduce the co-efficient of friction and permit the tool to perform better “in the cut”. As we talked about in the above section, with regard to geometry, we make every attempt to reduce the co-efficient of friction that a chip encounters as it is being formed into 6's & 9's in our end mills. We take special care to insure that our wheels are re-dressed often to maintain consistent surface finish. And that has an impact on coating adhesion as well. We'll be discussing that below. |
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Cutting Tool Coatings
We have spent a great deal of time insuring that our coatings work in conjunction with all the other aspects of our end mills. We have primary coatings for our tools.
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AlTiN — Aluminium Titanium Nitride.
This PVD coating has a gradually increasing percentage of aluminum added as it goes through the coating process. It gradually increases in the amount of Aluminum from the substrate interface until it reaches the outer surface of the coating, where there is a higher percentage (up to 65%) of aluminum in the film. As the tool heats up, the aluminum converts to aluminum oxide, staying in the film. This coating provides exceptional oxidation resistance and extreme hardness. AlTiN retains its hardness when the temperature is 800° to 930° C (1,470° to 1,700° F) This coating is ideal for dry machining environments. Used exclusively on our Raptor products for all: P – Steels (blue), M – Stainless Steel (yellow), K – Cast Iron (red), and S – Hi-Temp Alloys Special Alloys & Titanium (brown) materials. Please keep in mind that this coating CANNOT be used in Aluminum (N) machining because the Aluminum in it would have an affinity to itself and cause workpiece adhesion to the cutting tool. |
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X-Treme — Titanium Aluminium Nitride (TiAlN).
This monolayer PVD coating has high hardness and excellent thermal stability that protects against premature tool wear. It also has excellent oxidation resistance allowing for high speed and semi dry or dry machining operations. Used for our Cobra and Python series tools which are for all: P – Steels (blue), M – Stainless Steel (yellow), K – Cast Iron (red), and S – Hi-Temp Alloys Special Alloys & Titanium (brown) materials. |
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Black Stealth — Molybdenum Disulfide (MoS2).
The easiest way to understand our Stealth coating is to think of the coating as being ‘clear’ and not ‘black.’ As soon as the tool enters the cut many people comment that the “color has worn off.” We can assure you that this is not the case. There’s several physical and chemical changes that cause this visual change and space does not permit here to explain the science. That’s part of the reason we call it “stealth” because you can’t see it any more! What’s important is the this coating has a lower co-efficient of friction than just about everything else on the market. Our geometry works ideally with this coating. Used for our Viper and Diamond Back series tools which are for all Non Ferrous Alloy milling: N (green) materials. |
TiCN - used for Chamfer tools only
