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kommodore
06-22-2009, 11:35 AM
Hey everyone, i need to calculate how long is going to take to a band saw, to cut a 120mm round stock of 1045 steel.

i need to suppose some bandsaw i can find on the market.

is possible to calculate how long is going to take to make a cut on a round stock of Xmm diameter, knowing the bandsaw speed (cutting speed i guess) in [m/min] and the feed speed ??

thanks.

mrandrei
06-22-2009, 11:02 PM
I'm not good at equation, but there's a formula for computing the cutting speed. You can check out: www.ns-tool.com/english/technology/technology_03.html for that.

dr stan
06-23-2009, 01:28 PM
A lot will depend on the type of saw blade you use. Contact your industrial supply sales rep and have him or her contact the blade manufacturer.

kommodore
06-24-2009, 01:24 AM
thanks a lot guys, the link that you gave me, have some equations for the cutting speed and other things but for a milling machine or a lathe.

but thanks, i need to know the estimated time per cut, cause i have to make a cost estimation for some spur gears production (5000 pieces). so i need to put on detail every time asociated to every process. i allready have the times asociated to machining process, but i need to know the time involved on cutting the blanks from a steel round stock.

so anybody can tell me, based on your own experience, how long it takes to cut a 108mm diameter steel round stock with a bandsaw??? or any size of round stock, that you have ever cut.

so if you guys could tell me your experiences on cutting round stock with a bandsaw i could have and estimated time for cutting the 108mm round stock based on your experienced cutting times.

thanks

lotechman
06-24-2009, 02:23 PM
I used to cut 4 inch low carbon steel bar in ten inch lengths in batches of 20 to over 100. On the saw we had I was lucky to get ten pieces out every hour. I was facing the pieces and doing some minor machining and that was at best seven an hour. The size of your bandsaw will make all the difference. The one we had was a three phase five horsepower motor driving a blade that was one inch across. If your saw is not large enough it could take over ten minutes to make one cut.
You might get a quote on the bar stock in lengths and ask also if they will supply cut to length and request price... Often precut is cheaper than small machine shops can do.

Mondo
06-25-2009, 01:25 AM
Cutting speeds for metal saws is discussed in Machinery's Handbook, 28th Ed. on page 1053. The data below was taken from the table given on that page. The assumptions are this is for circular blades on which the saw teeth have a front rake angle of 20°, and a back rake angle of 8°. Cutting speeds are for carbon steel stock of the diameters given in inches.

1/4 - 3/4 * 3/4 - 1.5 * 1.5 - 2.5 * 2.5 - 3.5

160 sfpm * 150 sfpm * 150 sfpm * 130 sfpm
6.3 in/min * 5.9 in/min * 5.5 in/min * 5.1 in/min

sfpm = surface feet per minute

The table makes no mention of the impact of the number of teeth per inch.

I formatted this as best I could to prevent the site text interpreter from mucking with the white space and screwing up the table.

American Machine Tools web site has an in-depth discussion of band saws and power hack saws but falls short of providing any sort of calculation as you desire:

http://www.americanmachinetools.com/how_to_use_bandsaw.htm

Similarly, TheFabricator.com web site has a shorter discussion and may easily shed light on how the number of teeth per inch of blade (or more appropriatly how many teeth are in the cut) impacts efficiency, but offers no leads as to how to estimate the time for a given job.

http://www.thefabricator.com/Sawing/Sawing_Article.cfm?ID=448

My take on this subject is that there are many variables to be considered for calculating how long it will take to complete a given cut. Tooth count, hardness of material being cut, blade speed, tooth design, coolant used, if any, pressure applied to blade, material width and shape... etc. See if there are any engineering students at the local Community College who might be able to get extra course credit for preparing a paper on the subject! :blob4:

I hope this helps!

-Mondo

farmersamm
06-25-2009, 09:31 PM

OR JUST TAKE A PIECE OF SCRAP, OR STOCK, AND PUT IT IN THE VISE, AND SEE JUST HOW LONG IT TAKES IT TO CUT IT!!!!!

:cry::cry::cry::cry:

I'm on the railing, ready to jump:rolleyes::laugh:

farmersamm
06-25-2009, 09:32 PM
gee whiz!!!!!!!!

Sandy
06-25-2009, 10:17 PM
It seems like one of the larger user selectable variables in bandsaw cuts, and one only each particular user can decide, is blade life. You can't get that from tables, you establish it.

Increase the down pressure and/or sfpm and you've increased the speed of the cut as well as shortened the life of the blade. Back off on the pressure and/or sfpm and the blade lasts a lot longer and the cuts take longer too. Pretty simple. You can make a lot of cuts in a hurry if you want to throw blades at it.

You have to decide what it is you want in the production environment. High production at a high consumable cost, lower production at a lower consumable cost, or even blades that last forever because they aren't cutting anything.

Magnetic Mechanic
06-25-2009, 10:33 PM
thanks a lot guys, the link that you gave me, have some equations for the cutting speed and other things but for a milling machine or a lathe.

but thanks, i need to know the estimated time per cut, cause i have to make a cost estimation for some spur gears production (5000 pieces). so i need to put on detail every time asociated to every process. i allready have the times asociated to machining process, but i need to know the time involved on cutting the blanks from a steel round stock.

so anybody can tell me, based on your own experience, how long it takes to cut a 108mm diameter steel round stock with a bandsaw??? or any size of round stock, that you have ever cut.

so if you guys could tell me your experiences on cutting round stock with a bandsaw i could have and estimated time for cutting the 108mm round stock based on your experienced cutting times.

thanks

If you want to make time, hob your billit before using the band saw.