How to use 45 or 90 degree face milling cutter?

In some working conditions, workers may face to a problem which degree face mills shall choose? 45 or 90 degree? Of course, it’s better to have both 45 and 90 degree facemills but what are the conditions for each one?

Usually, your cutting tool supplier will suggest the 45 degree face mill is a better bet for general purpose face-milling. 

Below we would like to discuss about those face mills:

The arguments may appeared on those working condition for choosing the 45 are:

– Cutting forces are better balanced so that axial and radial forces are about even. Lowering the radial forces for purpose of more balanced with axial can not only enhance the surface finish, it’s also kinder to your spindle bearings.

– Cut entry and exit are better behaved–less shock, less tendency to break out.

– The 45 degree cutting edge is better for demanding cuts.

– The chip thinning effect is at work and leads to higher feed rates.

– The 45’s tend to have less tendency to chatter as well.

At one time, octagonal face mills were at war with the 45 degree face mills for supremacy. The octagonal inserts have more edges, so you can rotate the insert if one gets chipped. But, tooling costs are usually only about 3 percent of the manufacturing cost, so the greater efficiency of the 45’s eventually won out. Lately, you can get some face mills that use a 45 degree insert that’s double sided, so we have the best of both worlds since these inserts now have 8 edges like the octagonal inserts.

Here’s a 45 degree lead facemill slogging right through a weld–they are a little tougher than 90 degree face mills!

Is there never a case where the 90 degree face mill is a better choice?

It’s biggest advantage is it can cut a square shoulder. In addition, 90 degree face mills are generally a little more compact, with a smaller body diameter, and they can reach a greater maximum depth of cut.

I keep a 2″ diameter 90 degree facemill in my shop as well as a 3″ Glacern FM45 45 degree face mill. The FM45 sees a lot more use for sure.

One last thought about face mills–they’re horsepower hogs. Don’t try to use too large a face mill on your machine. I’ve stalled the spindle of my mill running my 3″ pretty easily.

The text selecte from CNC cook book