MicroGroup, part of TE Connectivity, offers both vertical and horizontal milling solutions, with 3-, 4- and 5-axis capability. Most milling applications begin with solid stock material, from which features are added such as holes, corners, radii, grooves, contours and profiles. The individual features can be held to very tight tolerances, as well as the relationships of features to each other.
The vertical mill utilizes a spindle orientated vertically to the surface that is being machined. The spindle holds cutting tools that rotate at 6,000 to 30,000 rpm depending on the machine’s capability. The workpiece being machined is normally held in vise jaws or custom fixtures designed for a specific part.
The basic vertical mill is configured to machine in 3 axes (X & Y axis perpendicular to the spindle and the Z axis in line with the spindle axis). Vertical mills with a 4th axis capability have an additional axis that rotates perpendicular to the spindle axis, usually in line with the X-axis. Machines with a 5th axis capability have an additional axis that rotates perpendicular to the 4th axis.
The multi-axis capability allows features to be machined at any angle within the part and also provides capability for machining complex contours into part surface. In many cases, this multi-axis capability allows complex parts to be machined in one operation–significantly reducing the variation between critical machined features, reducing lead-time and minimizing costs.
The horizontal mill has its spindle oriented horizontally to the surface being machined. The machine has a built in rotary axis, which is perpendicular to the spindle (called a universal table) that provides a 4th axis machining capability. The rotary table holds the material to be machined in fixtures that are located on large mounting blocks (often called tombstones). There are normally several tombstones per machine, allowing a large number of parts to be placed onto the fixtures and run during one machining cycle. This is one of the reasons why the horizontal mill lends itself to high volume production applications where multiple parts can be run at one time, making it a more cost effective alternative to vertical milling in some applications. The horizontal mill also allows the loading and unloading of the tombstones to be done offline utilizing a pallet changing system, eliminating the machine downtime associated with that task.