Verticalmilling machine diagram

When two or more parallel vertical surfaces are machined at a single cut, the operation is called straddle milling. Straddle milling is accomplished by mounting two side milling cutters on the same arbor, set apart at an exact spacing. Two sides of the workpiece are machined simultaneously and final width dimensions are exactly controlled.

Straddle milling has many useful applications introduction machining. Parallel slots of equal depth can be milled by using straddle mills of equal diameters. Figure 8-29 illustrates a typical example of straddle milling. In this case a hexagon is being cut, but the same operation may be applied to cutting squares or splines on the end of a cylindrical workpiece. The workpiece is usually mounted between centers in the indexing fixture or mounted vertically in a swivel vise. The two side milling cutters are separated by spacers, washers, and shims so that the distance between the cutting teeth of each cutter is exactly equal to the width of the workpiece area required. When cutting a square by this method, two opposite sides of the square are cut, and then the spindle of the indexing fixture or the swivel vise is rotated 90°, and the other two sides of the workpiece are straddle milled.

Milling is a Substractive machining process that uses many machine toolsets to efficiently precision-cut a variety of materials (such as metals, plastics, or wood) into a defined geometrical part. Milling machines rapidly produce end-use parts by adopting 3- or 5-axis processes. Metal parts offer greater finishing choices, while machined plastic parts are completed as-milled and expose visible tool marks. While 3-axis machining is one of the most widely used techniques for part fabrication, its rudimentary simplicity limits it to parts that are not too deep; likewise, there are restrictions when machining a deeper part with narrow cavities. These limitations can lead to an inadequate finish as well as high labor costs. One advantage of 3-axis machining is its low cost. As the need for more sophisticated parts has emerged, 5-axis machining can work a part from five sides in a single operation, making it highly suitable for deeper parts originating from more rigid materials. It also ensures higher precision and rapidity while reducing tool vibration. Although 5-axis machining is faster, it does require a longer preparation time. The 1980s ushered in widespread utilization of Computer Numerical Control (CNC) milling in machine shops, eventually enabling hobbyists, artisans, and designers to access the technology. This has led to extensive industry application in jewelry, printed circuit boards, firearm parts, and fine art manufacturing. Today, CNC Pocket Milling is one of the most widely used operations in machining. CAD/CAM programming software enables machinists to machine away large amounts of material before finishing the part. Because this process maximizes the bulk of material removal, the aerospace and shipyard industries use it extensively. Consequentially, CNC gave rise to the transformation of milling machines into machining centers comprised of automatic tool changers, tool magazines or carousels, CNC control, coolant systems, and enclosures. These centers fall into two categories: Vertical Machining Centers (VMCs) or Horizontal Machining Centers (HMCs).