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## Numbers Behind High Speed Machining (HSM)

May 28, 2013, 7:01 am by Eldar Gerfanov (Admin)

HSM or High Speed Machining is becoming more and more popular each day.
Many of us have seen those youtube videos where endmlls remove large amounts of material at high speeds/feeds.

While definitions of HSM may vary between tool manufacturers and even individual shops, the physics behind it remain the same.

## What is HSM?

HSM is a complex of programming, machining and tooling techniques aimed at radical increase of productivity.

## Programming

The cornerstone of HSM is low radial and high axial engagement of an endmill with the workpiece.

There are many CAD/CAM systems that allow you to create HSM tool-paths. Mastercam's Dynamic milling and SurfCAM's Truemill are some of them.

When radial cutter engagement with the material is smaller than the radius of the tool an interesting thing happens.
Chip load- the distance the tool advances per cutter revolution per tooth- does not equal the actual chip thickness anymore.
Chip thinning mainly happens at radial engagements below 30% of the diameter.

 100% 1 50% 1 30% 1.091 25% 1.212 20% 1.641 15% 2.1 10% 4.375 5% 6.882

In order to get compensated chipload you need to multiply recommended by manufacturer chipload by the chip thinning factor.

Usual Radial Engagement for HSM toolpaths however is between 5 and 15%.

Axial depth of cut varies depending on geometry, but

## Plunging and Ramping Recomendations and Techniques

February 12, 2013, 1:03 pm by Eldar Gerfanov (Admin)

Quite often in order to start cutting in x-y direction you need to first plunge into the material.

Here is a compliled list of recommendations for different kinds of plunging that works in most if not all cases.

### Plunge with center cutting endmill:

• Regular Chipload/Number of flutes , half the cutting speed. (for 3 flute endmill divide normal chipload by 3)

### Ramp:

• Ramp Angle: Indexed/non center cutting endmills: 1-2.5 degree; Center cutting endmills- Up to 45 deg

### Ramp chipload ajustment for 4 flute Center cutting endmills:

• 0-2.5deg=100% of normal feedrate
• 2.5-5deg=75% of normal feedrate
• 5-15deg=50% of normal feedrate
• 15-30deg=25% of normal feedrate
• 30-45deg=5% of normal feedrate

Dont forget to reduce cutting speed for ramping above 5deg by half!

## Calculating Tool Engagement Angle, Radial Depth of Cut

August 18, 2012, 11:14 am by Eldar Gerfanov (Admin)

Here i will show you how to calculate Tool Engagement Angle using tool diameter and Width Of Cut (radial deopth of cut)

Lets first draw a pretty image that shows us everything we need.

Where:

• r: Radius of the cutter = Diamater /2
• a: TEA - Enagagement angle we are trying to find here
• WOC: Width of cut or RADIAL Depth of Cut
• r2: The difference between r and WOC, r=r2+WOC

Below we develop 2 formulas that allow us to find TEA and WOC