Hi Everyone I could really do with some help with some rough milling . ( the finish is not important I have a grinder ....lol )
CNC Machine cincinnati Arrow 500 max spindle speed 6000rpm
Material to be machined S355 structural steel plate 30mm thick
aiming to achieve a slot 38mm wide 18mm deep and approx 370 long with half a radius in it R70 ( kind of horse shoe shaped )
I have all the dimensions correct ( g code etc. ) and the work piece is bolted down very securely but it seems to me that it takes forever to get the material out . I think im right in saying there is about 253 cubic cm and it is taking about 30 minutes or more to get this material out with cuts 1.5mm deep . I have seen cutters on manufacturers websites removing 1000 cubic cm in 1 minute . Now I know that is their claims and they have the latest cutters and best machines but that would take me 2 hours to do the same amount of work .
The other problem is the amount of carbide tips that are being used . The cutter has 2 teeth and they need turning to a new edge after just one pair of these .
The tips used are ( Grade P3500 ) http://www.cutwel.co.uk/milling/indexable-milling/indexable-milling-inserts/lnmx-korloy-rich-mill-rm4-milling-inserts
The cutter being used is 18mm 2 teeth http://www.cutwel.co.uk/milling/indexable-milling/rich-mill-indexable-milling-family/rich-mill-rm4-90-degree-indexable-end-mill-for-lnmxlnex-insertsr4mps-series
The guy who has been doing the programming for me has been absolutely great and has done it all with no manual for the machine or anything . He is not a programmer just a machine operator and I didnt want to annoy him by getting someone to advise on the last piece of the puzzle , which is the correct cutter at the correct speed getting the time down to more like 10 minutes which I don't think is unachievable ,
Please could any one help with this so I can get the time down on this .
Thanks in advance
I think you'd be better off taking as deep a cut as possible and you should generally use a 4 or 5 tooth cutter for steel. There is a way you can calculate exactly but you need to know a few specifics of your machine and the tool. The motor torque curve, ballscrew lead etc and the tool manufacturer will have a datasheet with the chipload etc. The most important thing is chip load, which is how much each tooth cuts per revolution.
You can figure it out by trial and error though, this is a good video series that will explain it all for you.
Ring Cutwell and speak to technical they are very helpful and will advise based off that cutter/tips.
If your not aware S355 is Low carbon steel with hardness between 470-630mpa (BHN 135-190) which is often used in calculating cutting data.
Really you have the wrong tool for the Job and like Rufe says 4 or more flutes would be better for this material.
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