Work holding devices securely and accurately position workpieces on a milling table. Vises are the most common devices used in milling.

The light coat of rust preventative such as Boeshield T-9 or LPS-3 is recommended prior to mounting. Parallel alignment of the fixed vise to the X-axis is accomplished with a dial test indicator. This vise is out of alignment by 4 thousandths of an inch per 6 inches. With the bolts partially tightened, the vise can be manually bumped into near perfect alignment. Some vises can be mounted lengthwise along the table or sideways for holding workpieces vertically.

Parallels are used to elevate the workpiece giving clearance for side milling and through-hole drilling. Thin parallels as well as wavy parallels are used for thinner workpieces. Jaw plates in the outboard positions of the vise jaws allows clamping of large plates. Double-station vises hold 2 workpieces for added productivity.

Vee blocks hold cylindrical workpieces and can quickly and accurately locate the Y-axis center. The v-block can also hold round bars vertically or other work holding devices such as collet chucks. A vise can be held within another vise as demonstrated with this sine vise.

Step clamps are easily adjustable in height for mounting workpieces directly to the T-slot table. Care should be taken to ensure the clamp is parallel to the surface of the table and not tilted. The possibilities are limitless. In this example, a lathe chuck is used to hold a large tubular steel workpiece.

CNC Mill Operation - Produced by Glacern Machine Tools - A Crash Course - Chapter 3

A Vertical Machining Center (VMC) is an automated CNC milling machine. Various tools can be held in the cartridge spindle. A pull stud is threaded into the back of each tool holder. An electronically actuated drawbar interfaces with the pull stud to quickly release the tool from the spindle, or to firmly secure the tool in the tapered spindle socket. This method of tool retention offers high reliability making it ideal for use with automatic tool changers.

The electrical cabinet mounted to the back of the machine contains most of the electronic components. The control panel provides a user interface for various operations. When set to automatic mode, the machine reads programs stored in memory. Programs typically contain many lines or blocks of code, and each block contains instructions for various machining operations.

With the machine in MDI (Manual Data Input) mode, blocks of code are written one by one on the keypad, often for setup and diagnostic purposes. S100 M03 rotates the spindle in the forward direction at 100 RPM. S5000 speeds up the spindle to 5000 RPM. M05 stops the spindle. Replacing M03 with M04 rotates the spindle in the reverse direction. Electronic hand wheels called Manual Pulse Generators (MPG) are used to manually position the machine table or spindle to exact locations.

An MPG mounted to a Control Pendant allows the operator to get closer to the machine for a better view. Jog and Rapid buttons are used for quick rough positioning of the table and spindle.

Coolant pumps can be activated with the keypad or with an M08 code. Water-soluble coolant is used to remove heat and clear chips - as well as periodic machine washdowns. Chips are removed by conveyors; auger type, flat-belt type or both.