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3D SURFACE MACHINING

ANESIMIN

By ANESIMIN,
in Industrial Forum

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ANESIMIN Rookie

ANESIMIN

Posted
Posted

Hi experts

i have some questions  regarding 3d surface  machining .

- how much stock to leave after roughing operation

-how much stock to leave after semi finishing operation

-the scallop high (step over) in finishing operation: some says that the step over should match the chip load per teeth  :

https://www.youtube.com/watch?time_continue=253&v=XSiPWq4Osmw&embeds_referring_euri=https%3A%2F%2Fwww.ultrapolishing.com%2F&source_ve_path=MzY4NDIsMzY4NDIsMzY4NDIsMzY4NDIsMzY4NDIsMzY4NDIsMzY4NDIsMzY4NDIsMzY4NDIsMzY4NDIsMzY4NDIsMzY4NDIsMzY4NDIsMzY4NDIsMzY4NDIsMzY4NDIsMzY4NDIsMzY4NDIsMzY4NDIsMzY4NDIsMjM4NTE&feature=emb_title

 

-when finishig :  -is it better to machine the flat surfaces with flat end mill or use a ball nose end mill .

                              -Is it better to finish all surfaces using the same ball nose end mill with the same toolpath  if possible , or use separate tool diameters with different strategies.

I will appreciate your help

 

 

 

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JParis Mentor

JParis

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I prefer to teach someone using a file of theirs...so much YouTube content, some is really good, some falls into hack territory...I don't bother with it anymore.

There is no straightforward answer...

How much stock after roughing?  Varies, are there other operations to be perform, stress relieving, cryo, going to another machine for finishing...and more

How much stock to leave after after semi?  Again, see above but then add material type, allowance for part movement...and more

Stepover?  Size of tool, style of toolpath used, material, finish requirements...there are scallop calculators out there... flat surfaces general cut paster with flat or bullnose, geometry dependent...

and for all of the above....machine abilities...what can it hold?

There are more answers to these questions than just X, Y, Z

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riverhunter Contributor

riverhunter

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I try to always finish anything flat with a flat end mill.  when surfacing i always try to use as much on the radius as i can.  try searching for some online calculators that will help you figure out step over vs ridge height.  when machining hard materials, surface speed varies a lot depending on how much material was left being vs tool engagement.  stock left behind will always affect step over distance.

image.png.fe36c4a3220d156fc94e846396bc81ba.pngimage.thumb.png.ca2ac38d5c6b99d3c0990ab248b986be.png

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ANESIMIN Rookie

ANESIMIN

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2 hours ago, JParis said:

I prefer to teach someone using a file of theirs...so much YouTube content, some is really good, some falls into hack territory...I don't bother with it anymore.

There is no straightforward answer...

How much stock after roughing?  Varies, are there other operations to be perform, stress relieving, cryo, going to another machine for finishing...and more

How much stock to leave after after semi?  Again, see above but then add material type, allowance for part movement...and more

Stepover?  Size of tool, style of toolpath used, material, finish requirements...there are scallop calculators out there... flat surfaces general cut paster with flat or bullnose, geometry dependent...

and for all of the above....machine abilities...what can it hold?

There are more answers to these questions than just X, Y, Z

Thank you for your feed back

Could you suggest a guide that helps.

 

 

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ANESIMIN Rookie

ANESIMIN

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2 hours ago, riverhunter said:

I try to always finish anything flat with a flat end mill.  when surfacing i always try to use as much on the radius as i can.  try searching for some online calculators that will help you figure out step over vs ridge height.  when machining hard materials, surface speed varies a lot depending on how much material was left being vs tool engagement.  stock left behind will always affect step over distance.

image.png.fe36c4a3220d156fc94e846396bc81ba.pngimage.thumb.png.ca2ac38d5c6b99d3c0990ab248b986be.png

Thank you so much.

So to get a better surface finish (Rt) , a minimum axial cut  (ap) and maximum tool radius are required according to the picture below.

But when cutting  a very smal thikness (ap),  this will affect the chip load per teeth required by the tool manufacturer : how to solve this ?

So should i start by the finishing operation and adequate tool to know how much stock to leave in semi finishing or roughing operation?

I ask  for the methodology  in general.

Again thank you for help.

 

image.png.cce09e84ff96510e1b5b59f927840c11.png

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riverhunter Contributor

riverhunter

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Do some testing and find out what works best for you.  15 years ago i relied on excel files with all kinds of crazy formulas.  now days its just experience.  Below is an example of what i use.  the 25% / 50% rule has been fine for me.  you can see the pattern in the step over and stock.

Ø.750 bem rgh step over .1875 leaving .060 ( just go for it )

Ø.750 bem semi fin step over .046 leaving .030  ( adjust feed rate for stock left behind )

Ø.750 bem fin step over .012  ( really adjust feed rate for stock left behind )

FINISHING BALL ENDMILLS                                                  
  TOOLPATH                    REL DIA   REL LEN           CLAMP   REC   REC    ADJ   STEP       TIP    STOCK       COOL                           ADJ   ADJ   ADJ   ADJ TO   ADJ   ACT   SURF TIME PER        
TYPE TYPE   DIA   FL   C/R   LOC   RD   RL   PRO   MAT   DEPTH   SFM   CPT   RPM %   OVER   DOC   SURF   LEAVE   HPF   STYLE   MAN   PART#   HOLDER   RPM   FEED   ACPTF   CPT   DIA   RPM   MAX RPM   FEED   SFM   FINISH SQ IN   HP   CIPM
BEM SURF PARALLEL   0.7500   2   0.375   1   0.73   2.5   2.6   6061   0.100   1500   0.0091   100%   0.016   0.030   SURF   0   3.5   FLOOD   DATA FLUTE   HSM-BM-M-20750   .750 SOLID   7640   139.0   0.3919   0.0232   0.526   10900   10000   464.4   1950   64 0:00:08   0.0637   0.2229
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ANESIMIN Rookie

ANESIMIN

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1 hour ago, riverhunter said:

Do some testing and find out what works best for you.  15 years ago i relied on excel files with all kinds of crazy formulas.  now days its just experience.  Below is an example of what i use.  the 25% / 50% rule has been fine for me.  you can see the pattern in the step over and stock.

Ø.750 bem rgh step over .1875 leaving .060 ( just go for it )

Ø.750 bem semi fin step over .046 leaving .030  ( adjust feed rate for stock left behind )

Ø.750 bem fin step over .012  ( really adjust feed rate for stock left behind )

FINISHING BALL ENDMILLS                                                  
  TOOLPATH                    REL DIA   REL LEN           CLAMP   REC   REC    ADJ   STEP       TIP    STOCK       COOL                           ADJ   ADJ   ADJ   ADJ TO   ADJ   ACT   SURF TIME PER        
TYPE TYPE   DIA   FL   C/R   LOC   RD   RL   PRO   MAT   DEPTH   SFM   CPT   RPM %   OVER   DOC   SURF   LEAVE   HPF   STYLE   MAN   PART#   HOLDER   RPM   FEED   ACPTF   CPT   DIA   RPM   MAX RPM   FEED   SFM   FINISH SQ IN   HP   CIPM
BEM SURF PARALLEL   0.7500   2   0.375   1   0.73   2.5   2.6   6061   0.100   1500   0.0091   100%   0.016   0.030   SURF   0   3.5   FLOOD   DATA FLUTE   HSM-BM-M-20750   .750 SOLID   7640   139.0   0.3919   0.0232   0.526   10900   10000   464.4   1950   64 0:00:08   0.0637   0.2229

 

i will focus on those calculations in the beginning .

Would you suggest a reliable  file or site .

 

Thank you Riverhunter , love you.

 

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