I am not a machinist, we did not use a lot of end mills. I was in the cabinet making / woodworking / mill work, store fixture, and Trade Show exhibit business. We used machining centers and table routers. Different kind of tooling for different material... Mostly hardwood, MDF, and different types of plastics. When cutting stencils out of 1/16" PVC I would rout slots about 1/8" deep in a sheet of MDF the same pattern as the stencil to catch the chips... The 1/16" PVC was laid on the MDF held down with vacuum pulling through the MDF, using 1/6" plastic-cut down-cut bits to help hold the the PVC to the table. An up-cut would tend to lift the small part parts off the table.
We would also use down-cut bits on veneer-ply to prevent chipping or splintering...
Note: They are call plastic-cut as the geometry of the bits are especially designed for cutting plastic. They have this geometry down to a science... Every material cuts different and have router bits with different geometry.
MDF is porous, you can pull a vacuum through it for holding down materials...