We all have manufacturer speed & feed charts and have used their recommendations.

But sometimes those charts just don't apply.

For example manufacturer charts assume you are using their endmills at a certain stickout length, flute length and at a certain depth of cut.

But in the real life you rarely match all these conditions.
Sometimes you need to use longer endmill. Sometimes your flute is longer than what manufacturer gave you speeds and feed for.

What i am trying to say is that whenever your real life conditions differ from "normal" you "need to adjust accordingly".
In fact this is what is printed below many charts.

Too bad not many sources tell you how and what to adjust.

While failure to adjust cutting parameters often leads to chatter, poor surface finish and even tool breakage, one of the biggest mistakes people do when machining is Read More 

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.

In this article i would like to explore flat endmills.

HSM is not about ramping up your speed/feed overrides to 200% and puling out your smartphone to record another youtube-worth video.

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.

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 Read More 

Radial Chip Thinning HSMAdvisor Screenshot

Sometimes people ask me: "I tried your calculator, and i liked it, but it seems to me a little too aggressive...do you actually do any testing?"

Well, to those I say that not only i do testing, but i run production jobs 100% calculated with my own HSMAdvisor.

Many machinists say that nothing beats an experienced operator holding his hand on feed hold button and playing with speed and feed override trying to find the "sweet spot" where cutting speed and feed rate are maximized and chatter is eliminated or reduced.

And it is correct, but not any machinist is experienced or actually knows what he is doing.
Many machinists also finish their apprenticeship program and never learn a single thing about new tooling types and materials since. They bag years of experience, but their knowledge is stuck on a level it was when they first got their license.

Also not a single person can possibly know cutting conditions for hundreds of materials and remember all of the jobs he had ever ran.

This is where tool database comes in.

Not only can you save tools to cut down and in many cases eliminate entering parameters for every calculation.
But you can (and should) save cutting data for each particular case.

A single tool entry can contain an unlimited number of cuts attached to it, so machinist never has to remember everything.

Here is a i made video of slotting D2 with variable helix hi-performace endmill.

Material: D-2 Tool Steel 200-250 HB
Tool: 0.500in 4FL Carbide TiAlN coated Solid HP End Mill
Speed: 360.0 SFM/ 2751.6 RPM
Feed: 0.0023 ipt/ 0.0094 ipr/ 25.76 ipm

Engagement:  DOC=0.330 in   WOC=0.500 in

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 Radius (For Helical ramping): .90-.95 of cutter radius

• 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!

Here are some samples of nested parts i did recently

In both cases back of all pieces were machined at the same time, dowel holes milled so that there would be a way to align top and bottom.

Ealot of material was lost, but it was a scrap anyways, so all i gained was alot of saved man-hours.

And here are 4 more pictures:

Read More 

Hi-helix end mills have several advantages inherited with their design.

Simple math says that a an endmill with 45 degree helix angle directs 50% of the cutting force downward versus  25% for a 30 degree end mill.

Main advantages are:

• Higher rake angle directs more of a cutting force downward.
  This reduces side load on the cutter, that leads to less deflection and less tendency to chatter.
• At high axial engagement (deeper depths of cuts) more flutes remain in the contact with the work piece. This leads to much smoother cut, again reducing tendency of the cutter to chatter.
• High helix angle pulls chips upward and away from the cutting zone.
  This reduces chip re-cutting and helps prevent cutter from getting clogged up. This also allows to take deeper cuts and increases productivity.
• Because of higher helix more of flute length is being used in the cut. Better surface finish is achieved even when using the same chip load.
  Generally an end mill with 45 degree helix can be fed 30% faster than equivalent one with 30 degree helix and still achieve same surface finish.

High helix end mills also have disadvantages that a machinist has to take into consideration:

• With more of cutting force directed axially, the load on spindle bearings in downward direction is increased.
• Tendency for both the end mill and the work piece to pull out is increased. So a more rigid tool holding and work clamping should be considered.
• Higher helix end mills are also less stiff that regular helix end mills. This may cause more deflection and may become a problem when having to machine straight walls.
  This effect should be mostly diminished by lower side radial load, but it still needs to be considered in some cases.

Tired of printing out Operation lists and then wasting time adding setup information by hand?

There is a neat and easy way to replace standard Operations and Tooling lists with something very compact and usable.

Here are config files i use at my work to create Setup Sheets and tooling lists right from SurfCam.

1. First make sure you backup you Operations.cfg and Tooling.cfg files in case you want to go back (VERY NOT likely)
   Those can be found inside your V5 or V6\Config directory.
2. Unpack contents of the attached ZIP folder.
3. Copy .CFG files found within into your V5 or V6\Config folder.
4. Copy folder "images" into "C:\Surfcam" directory, if you want also tool images to show with tooling list.
5. Go to SurfCam Options and in section Setup Sheet select "Current" from several other choises.

Thats it!!

UPDATE!!!!!!

• Operations list NOW highlights table rows when you move the mouse over them.
• When you select ANY text on Operations List, the same text will be highlighted over the whole page!!!

Download current file below

Samples are below:

Read More 

Surfcam_custom_operations_cfg.zip Size:0.11 MB

Using Peck Cycle is often needed when drilling deep holes.
When using proper feed and speed no peck is required at depths of up to 3xDia for regular or 5xDia for High-Performance Parabolic drills.
At depths up to 10x, up to 5 pecks are required for regular  drills and up to 3 for Parabolic.
Anything over 10x Dia requires constant pecking of 0.5-1x Dia for regular drills and 1.5-2 Dia for Parabolic.

Since for programming you need a peck amount. Here are the numbers:

Of course our HSMAdvisor Speed and Feed Calculator suggests not only the Speeds and Feeds but also the proper peck depth for various drill types and depths of the hole.
It in fact was the first machinist calculator to do so. This feature was much later borrowed by our competition.

And here is a pretty image showing Peck VS Hole Depth for regular twist drill:

This not only means that peck amount should be different for different styles of drills and depths of holes.
But also that peck distance should be different for different stages of drilling the same hole.
Ideally we should start the hole with large pecks, that continually reduce as the hole gets deeper and deeper.

Let's find out how we can apply this knowledge when programming our toolpaths.
This is format for normal Pecking:

Read More 

Renishaw OTS tool probe cycle for HAAS can set both length and diameter offsets.

Too bad there is no choice: it only puts absolute measured diameter of the tool into D- diameter offset and makes wear offset=0

But if your programming is done with the center of the cutter, then you actually only need the difference between actual and programmed diameters of the tool.

I.E.: When probing 5/8Dia end mill, we get D=0.6248. You would normally have to subtract 5/8 from it and leave the -0.0002 difference.

But there is an easier way

Read More