Up-cut and climb milling

The Shed - - Milling -

For ef­fi­cient cut­ting, the cut­ting edge must ar­rive at the work­piece first. If not, it may still cut but ex­ces­sive heat will be pro­duced by the tool rub­bing. In ‘up-cut’ milling (or con­ven­tional milling) the tool starts at the bot­tom and cuts up­wards. The cut­ting edge rubs mo­men­tar­ily un­til it bites into the cut, which is no prob­lem when the cut­ter is sharp. When the cut­ter dulls, the cut­ting edge rubs more. This be­comes ev­i­dent in the re­sult­ing poor sur­face fin­ish.

In ‘climb’ milling, the cut­ter is try­ing to climb over or along the work­piece. As the cut­ting edge takes a full cut straight away, there is no rub­bing and a bet­ter sur­face fin­ish re­sults. The size of the swarf chip is the same by both meth­ods.

To get the ben­e­fits of climb milling you need higher spin­dle power and a very rigid set-up for your ma­chine, com­po­nent, and tool hold­ing. Un­less your ma­chine is fit­ted with ball screws or back­lash elim­i­na­tors, you will have to up-cut mill. If you try to climb mill, the tool will con­tin­u­ally grab the work­piece as it takes up the back­lash in the ma­chine lead screw as you feed the ta­ble. This will re­sult in a poor fin­ish or dam­age to the work­piece and pos­si­bly chip­ping of the cut­ting edges or break­age of the cut­ting tool.

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