speed and feed

How does one find out what the correct speed and feed rate? Im sure steel has a different s&f than aluminum so the numbers would be different. I have the machinists calc pro and when you input the numbers it doesn't know what material is chucked up so how do I make sure I am giving it the right figures ?

I use Gwizard at www.cnccookbook.com It is not free but it is very good.

Dave

Is there a table that lists the numbers? Is the information in the machinerys handbook?

One trouble with tables is they have no flexability.One of the big killers of end mills is deflection. You can see what your deflection number is and if it goes beyond recommended it turns red so you can adjust your numbers.

Dave

Dave Sohlstrom said:

One trouble with tables is they have no flexability.One of the big killers of end mills is deflection. You can see what your deflection number is and if it goes beyond recommended it turns red so you can adjust your numbers.

Dave

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I don't have anything in my shop that turns red. What are you talking about.

I'm sorry. that is related to the program Gwizard when you are using it to get the best feed and speed for the job you are working on. Are you machining with CNC or manual machines.

Dave

Dave Sohlstrom said:

I'm sorry. that is related to the program Gwizard when you are using it to get the best feed and speed for the job you are working on. Are you machining with CNC or manual machines.

Dave

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manual, no cnc.

kd0afk said:

How does one find out what the correct speed and feed rate? Im sure steel has a different s&f than aluminum so the numbers would be different. I have the machinists calc pro and when you input the numbers it doesn't know what material is chucked up so how do I make sure I am giving it the right figures ?

Click to expand...

All you will need is here and more.... all free
enjoy

http://www.home-machine-shop.com/Down-Load/Down-Load.htm

kd
Milling 920 rpm feed 100 mm/min, turn 500rpm .005"/rev with power feed anything from ally to stainless apart from titanium TA11 it works ok for me for a hobby job this is either hss or carbide
Ray

So with a manual lathe its not that crucial?

as a rule i would say no the power feed gives a more consistent finish for parallel turning or facing but with a 'delicate' tool thin groover etc feed by hand carefully the only time i change speed would be for tapping or external threading with diehead from the tailstock usually 50 rpm and feed by hand
Ray

The problem I have with S&F is I have no idea what value to use for chip loading. If I understand it correctly it varies with each end mill and the type of material being milled.

Pat

have the machinists calc pro and when you input the numbers it doesn't know what material is chucked up so how do I make sure I am giving it the right figures ?

Click to expand...

Any good machinist book should have a list/table of recommended cutting rates for common materials. for what they charge for the machinist caculator you would think they could throw one in .
Tin

As Tin pointed out, most technical machining books ( ie. a book from a technical insitute teaching machining) have a chart in them.

I have been guilty of this in the past about taking too little of a chip load say less than 0.001" and have prematurely dulled a cutter. With less than particularly 0.0005" chip load on lathes and say 1/4" and up end mills either HSS or carbide, there is more of a rubbing action than a cutting action. I'm not saying that there aren't times when to get in size you do need to cut with a small chip load to get that darned dimension ie. bearing fit. With the machinery's handbook one can get lost in it trying to find information. Don't get me wrong, I look up stuff all the time in this book. There are books that have the info in easy to find charts. I have my own chart laminated for quick reference but cannot share due to copy write laws.

One thing I can say is the insert/end mill manufactures sometimes have charts on their web site or catalog.

I have the exact calculation for you it will have to wait till tomorrow though, I have a speeds and feeds card in my machining class locker at school

Try this, it's incredibly helpful and free.

http://zero-divide.net/index.php?page=fswizard

first thing i have to say is google is your friend. more specifically wikipedia is your friend...

for feeds and speeds you need to know 2 things. the velocity the the material passes the cutting edge or cutting edge passes the material. and how much the cutting edge takes off at a time. the first part is easier to find an ideal number as there are charts based on the material in any reference book and will work into a formula with the diameter for the rpm. the number (in imperial measurments) is surface feet/min or sfpm. you use the part diameter for a lathe and the endmill diameter for a mill. though on a cnc lathe you can actually set the sfpm and the spindle will turn the rpm calculated for the x position of the tool up to a max set rpm. you may find that for soft materials and small diameters you come up with unreasonably high rpm. you can usually go slower with no problems as long as the feed is set based on the actual rpm not the calculated.

the formula is often simplified and rounded to rpm = 4*sfpm/diameter(in inches)

then the next part is the chip thickness or chip load. chip load can vary a lot on a lathe and depends on the rigidity, desired surface finish, and tool radius. a bigger radius will allow for a faster feed and/or less tool marks but on a hobby sized machine and small parts it will likely chatter if the radius is too big. this really comes down to preference and experience but generally you can get more chip load on aluminum and other soft materials. since on most lathes you are dealing with gear drive and cnc lathes can be set for feed/rev you don't need to convert to ipm or mm/min. on a small lathe i think somewhere between .002 to .008 per rev is a good range.

on a mill chip thickness has to do with rigidity and chip clearance. a 2 flute endmill can take a thicker chip than a 4 flute and often the feeds end up being close. on a hard material the chip load may be .001-.002 (with titanium as an exception for a few reasons, don't try to mill titanium unless you have zero backlash and/or you really know what you are doing...) and on a soft material it may be .005-.010. i dont know if i'd go .010 per tooth on a hobby machine though...

http://en.wikipedia.org/wiki/Speeds_and_feeds

^ this article pretty much covers it. there is more that you can get into like finding horsepower requirements and cutting force for high speed machining but generally the machine wil tell you if you are being too aggressive.

Tin Falcon said:

Any good machinist book should have a list/table of recommended cutting rates for common materials. for what they charge for the machinist caculator you would think they could throw one in .
Tin

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did anyone check the site i posted earlier
http://www.home-machine-shop.com/Down-Load/Down-Load.htm

That's a great link Vidio! Thanks.

Speed And Feed Calculation:

SFM= RpmxDia/3.82
RPM= 3.82x SFM/dia
IPM= Iptx # of teethx rpm
IPT= IMP/(# of teethx rpm)
IPR= imp/rpm
CIM= fdx wocx doc
HP= CIMxUHP