Information on How to Operate a Milling Machine

Milling machines use drills as well as end mills to cut material.

Milling machines are used in machine shops to fabricate parts using raw materials of various types including steel, aluminum, graphite, plastic and wood. To machine the material properly, you must know how to operate the milling machine and use its many features. With a little practice and hands-on experience, you can operate a milling machine to make a part based on a blueprint.

Things You'll Need

• Wrench
• Vise or fixture
• Raw material
• Dial indicator

Instructions

1. Turn the machine on and run the spindle to distribute the oil and lubricate the moving parts. Sometimes milling machines can sit idle for days or longer, so they should be run at about 1,000 rotations per minute (rpm) to lubricate and prevent any workload damage. Maintain the rpms for at least 10 minutes for proper lubrication and turn the spindle off before working near it to prevent injury.

2. Insert the tool you will use for milling, which can be an end mill, drill or other milling machine tool. Loosen the draw bar at the top of the spindle head and place a new collet or tool in an existing collet and tighten the draw bar with a wrench while holding the spindle lock. If you have trouble doing that, place the gear handle in between gears to lock the spindle so you can use both hands.

3. Turn the spindle on and adjust the speed based on the tool diameter as well as the material you will be cutting. Slower speeds are great for steels and harder material as well as tools over 1 inch in diameter. Fast speeds are useful for aluminum, wood or plastic or small drills and end mills. Never adjust the speed control with the spindle off as you may break the drive belt when you turn it on after an adjustment.

4. Place a vise or fixture on the work table and tram it to make sure it is straight. Place a dial indicator and holder on the spindle and place the tip on the front edge of the vise or fixture. Move it in the X-axis direction, back and forth. Look for needle movement, which indicates that the fixture or vise is not straight, and make the necessary adjustments to the vise or fixture until the needle does not move across the entire length.

5. Place the raw material in the vise or fixture and set the zero based on the dimensions in the print. Some mill users use one corner of the part while others set the center as the zero point. You can reset the traverse micrometer wheels to zero to make accurate cuts in the raw material.

References

• American Machine Tools: How to Use a Milling Machine