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Milling machine
A milling machine removes material from a work piece
by rotating a cutting tool (cutter) and moving it into the
work piece. Milling machines, either vertical or hori-
zontal, are usually used to machine flat and irregularly
shaped surfaces and can be used to drill, bore, and cut
gears, threads, and slots.
The vertical mill, or “column and knee” mill, is the most
common milling machine found in machine shops today.
The general construction of this mill includes the quill,
which moves vertically in the head and contains the
spindle and cutting tools. The knee moves up and down
by sliding parallel to the column. The column holds the
turret, which allows the milling head to be positioned
anywhere above the table. Hand wheels move the work
table to the left and right (X axis), in and out (Y axis), in addition
to moving the knee, saddle, and worktable up and down (Z axis).
Hazard
Serious injuries and entanglement can occur if the operator con-
tacts the rotating cutter. Metal shavings and lubricating/cooling
fluids might also present a risk from the point of operation area.
Material might spin and strike an operator if the material is not
secured to the table.
Injuries can also occur from a projected wrench if it is left in the
spindle.
Solution
Secure the work piece either by clamping it onto the work table or
by clamping it securely in a vise that is clamped tightly to the table.
NOTE: Computer numerical controlled (CNC) mills
are rapidly replacing manually fed machines, mainly
for versatility and production reasons. The increased
automation does not normally require the operator to
move the hand wheels (like the traditional machines)
so operators must always keep their hands away from
the point of operation. A guard or shield that encloses
the cutter head or milling bed may be considered to
protect the operator from the cutting area, flying metal
shavings, and lubricating or cooling fluids.
Make sure the tightening wrench is removed from
the mill.
References
General Industry
Oregon OSHA Division 2/Subdivision O 29 CFR
1910.212 — General Requirements for All Machines
ANSI B11.8 Drilling, Milling, and Boring Machines
Ball State University
In some cases, a shield can provide an operator
protection from the cutter as well as from metal
shavings and metal working fluids.
Vertical “column and knee” mill.
Illinois Institute of Technology
Georgia Tech Research Institute
