Electrical Discharge Machining (EDM)

EDM, or electrical discharge machining, is capable of machining complex shapes in hard materials. The process includes an electrode and a workpiece, both submerged in dielectric fluid. Electrical current flows between the workpiece and electrode, repeatedly creating tiny plasma zones that instantaneously melt and remove the material. The electrode in EDM takes different forms. Wire EDM machines use a thin wire to cut. Ram EDM machines, or “die sinkers,” use electrodes that are custom machined into 3D shapes. The EDM process produces a cavity in the part that is the opposite or female version of the “male” electrode form. Similar to the ram EDM machine is the small-hole EDM machine, or “hole popper.” On this machine, the electrode is a cylinder used to machine a hole.

Grinding Equipment

Grinding is a machining process that takes a very light “cut” using abrasive media—typically an abrasive grinding wheel. Grinding wheels with different grit sizes achieve rougher or finer grinding passes, according to the needs of the application. When precise accuracy and/or surface finish are required, grinding is often used as a finishing process after some other metalworking operation. Grinding is also an effective process for machining workpiece materials that are too hard for milling or turning. Grinders for round parts include cylindrical and centerless grinders. Grinders for flat surfaces are called surface grinders. Form grinders move the work and/or the wheel in various axes to grind surfaces that are precisely contoured. Grinders used to create and sharpen cutting tools are called tool & cutter grinders.

Laser-Waterjet

Laser cutting is a method of cutting material using the energy of a highly concentrated beam of light. The beam of light is generated by a high-power laser, using optics to direct the beam to the workpiece. The laser beam melts, burns or vaporizes a very narrow slit through the material. Laser cutters are often applied to flat sheets or to formed pieces or tubes. Laser technology can also be used for welding, cladding, vapor deposition, engraving, trimming, annealing, heat treating and hardening.

Waterjet is a method of cutting material that uses the energy of highly pressurized water. Under as much as 90,000 psi, a fine stream of water passes through a nozzle with a very small orifice. The force of the water stream is sufficient to penetrate and cut softer materials. To cut harder, denser materials, an abrasive powder (usually garnet) is introduced into the stream.

CNC Machining Centers & Milling Machines

The term “machining center” describes almost any CNC milling and drilling machine that includes an automatic toolchanger and a table that clamps the workpiece in place. On a machining center, the tool rotates, but the work does not. The orientation of the spindle is the most fundamental defining characteristic of a CNC machining center. Vertical machining centers (VMCs) generally favor precision while horizontal machining centers (HMCs) generally favor production—but these are loose generalizations, and plenty of machining centers break out of them. Another common machining center type is the 5 axis machining center, which is able to pivot the tool and/or the part in order to mill and drill at various orientations.

5 Axis CNC Machining Centers

Besides the linear axes X, Y and Z, 5 Axis Machining Centers also move in two rotary axes, often identified as A and B axis. The rotary axes tilt the tool with respect to the part. Physically, it can be either the tool that tilts or the part that tilts. True 5 axis CNC machining uses these axes to smoothly follow a contoured surface. This type of machining has long been important in the aerospace industry, where machined parts follow the aerodynamic forms of aircraft. Some machines move the rotary axes only to position the tool or work outside of the cut. A machine capable of this “3+2” machining often can reach all of the machined features of the part in a single setup.

Horizontal Machining Centers (HMCs)

A horizontal machining center (HMC) is a machining center with its spindle in a horizontal orientation. This machining center design favors uninterrupted production work. One reason for this is that the horizontal orientation encourages chips to fall away, so they don’t have to be cleared from the table. More significantly, the horizontal design allows a two-pallet workchanger to be incorporated into a space-efficient machine. To save time, work can be loaded on one pallet of an horizontal machining center while machining occurs on the other pallet.

Vertical Machining Centers (VMCs)

CNC vertical machining centers (VMCs) remain machine shop staples. These milling machines have vertically oriented spindles that approach workpieces mounted on their table from above and commonly perform 2.5- or 3-axis machining operations. They are less costly than horizontal machining centers (HMCs), which makes them attractive to small job shops as well as larger machining operations. In addition, the performance of these machines has increased over the years, leveraging technologies such as high-speed spindles and advanced CNC capabilities (including conversational control programming). Ancillary equipment is also available to increase the flexibility and capability of these machines, including spindle speeders, angle heads, tool- and part-probes, quick-change workholding devices, and rotary indexers to enable four- or five-axis machining work.

Turning Machines

“Turning” defines the work that is traditionally done on a lathe. “Turning centers” is a term sometimes applied to machines with secondary spindles and/or rotating tools for milling and drilling. Another term, “turn/mill or multitasking” describes machines that can be thought of as being just as capable at milling and drilling as they are at turning. Lathes, turning centers and turn-mill machines can have horizontal or vertical spindles, with horizontal being most common. Machines with a vertical spindle are generally called a vertical turret lathe, or VTL. If the workpiece is held from above by the vertical spindle, then this type of turning machine is generally called an inverted vertical lathe.

Turn/Mill & Multitasking Machines

Turn/Mill Machines are capable of both rotating-workpiece operations (turning) and rotating-tool operations such milling and cross-drilling. The machine is typically recognizable as a horizontal or vertical lathe, with spindles for milling and drilling simply available at some or all of the tool positions. A part requiring a variety of operations can be machined in one setup, particularly if a subspindle allows the part to be passed from one spindle to another during machining. More recently introduced turn/mill machines depart from the lathe design into something much more like a hybrid machine—combining a lathe’s chucks and spindles with the travels and milling power of a machining center.