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Milling machines are commonly used in metalworking operations. This could be in the tool room or a high speed production line. Milling machines use complex, multi-tooth rotary cutters to make compound cuts. There are four standard types of milling machines. They are the bed type, column and knee, horizontal, and vertical milling machines.  This sheet describes the procedure for using a vertical milling machine to drill a hole and slot to make a key way. For other operations ask your instructor or refer to one of the many texts available. (The picture to the left is a thumbnail of a larger version.)

Controls: The controls on the vertical milling machine in the materials processing laboratory consist of the following:

• A magnetic power switch that must be reset if the power in the laboratory is interrupted. 
• A spindle break so that the spindle nut can be loosened to take the collet out of the chuck.
• A quill feed handle to manually feed the cutter into the stock.
• A quill lock to lock the cutter in place.
• A longitudinal feed screw handle to move the stock into the cutter on an x-axis.
• A cross feed screw handle to move the stock into the cutter on a y-axis.
• A knee height adjustment screw to position the depth of the cut.
• A high and low speed clutch knob.
• A back gear control knob.
• A power feed engagement knob.
• A manual feed knob.
• A feed control knob.
• A quill feed selector knob.
• A draw bar knob.

Operation (Drilling): Milling is the operation during which the stock is moved into the cutter on an x, y or z-axis to remove stock. All the operations that are described on this sheet are using a manual feed.  Refer to the following illustrations.

1. Select the proper cutting bit.
2. Place the bit in the spindle and make sure that the bit is at a right angle to the table.
3. Tighten the spindle using the nut on the top of the milling machine.
4. Place the stock in the vise and lock it in place.
5. Make sure that the vise is tight and holding the material securely by hitting the handle with a rubber mallet.
6. Position the cutter at the starting point.
7. Place a spot of cutting oil on the spot that is to be cut.
8. Select the right cutting speed, rpm, and rate of feed for the job.
9. Cut the stock using the cross feed or longitudinal feed controls.
10. Turn off the machine before removing the stock.

Potential hazards: Because of the rapid spinning motion of the milling cutter, the following hazards exist.

• Any body contact with the moving cutter will cause severe injury. 
• Clothing or other articles that contact the moving cutter could become entangled and pull the operator into the cutter. 
• The work piece can come loose from the vise if it is not tightened properly and do damage to the cutter and the operator.
• Small pieces of metal chips can be thrown out at the operator. 
• The operator could slip and fall into the cutter. 
• The cutter and the worker piece can become very hot.

• Be sure to perform only operations you know how to do safely. 
• Always wear safety glasses. 
• Never wear cloths or other articles that dangle and could catch on the cutter. 
• Be sure to have firm footing. 
• Check the machine to make sure it is in good working order. 
• Wipe up any oil that is on the floor around the machine.
• Be certain that the table is clean and dry before making a setup.
• Always make sure that work holding devices such as a vise, angle plate, dividing head, or tail stock are fastened tightly to the table.
• Select the right kind of cutter for the job.
• Make sure that the machine is turned off when putting in a cutter.
• Always make sure that the arbor, cutter, and collars are clean before mounting them in the spindle.
• Use a rag to handle sharp cutters.
• Use a rubber hammer to set the work piece in the vise securely.
• Be certain that the vise or other holding devices clear the arbor and the overarm supports.
• Select the proper cutting speed, rpm, and rate of feed for the job.
• Disengage the control handles when using automatic feeds.
• Keep hands away from the revolving cutter at all times.
• Clear chips away from the cutter with a brush.
• Release any automatic feeds after the job is complete.
• Do not allow unauthorized persons within the safety zone of the machine.
• Clean and wipe the machine when the job is finished.
• Never touch the metal chips with your fingers.

Feeds and speeds chart for the verticle milling machine

References:

Johnson, Harold V. (1973). Technical Metals. Chas A. Bennett Co., Inc. Peoria, Illinois.

Repp, Victor E. (1994). Metalwork: Technology and Practice. Glencoe Macmillan/McGraw-Hill. New York, New York. 9th edition.