It should be no surprise that Citizen, the famous producer of watches, is also a leading manufacturer of Swiss machining systems, since Swiss machines were developed to fabricate the small, intricate components of timepieces. While watch components remain a big Swiss machining market, the machines have evolved into systems of choice for a range of tiny precision metal parts.
With their penetration into various markets, Swiss machine makers are adding features to make metalworking operations more productive. Citizen, for example, has been promoting the Cincom L20X automatic CNC lathe, which incorporates numerous operations, on the trade show circuit. “The objective is to find more ways to implant processes in the machine and eliminate secondary and tertiary finishing operations,” says Andrew Shufelt III, an application engineer at Marubeni Citizen-Cincom Inc., of Agawam, Mass., a distributor of Citizen’s Cincom line of Swiss machines.
The Cincom L20X, which holds 39 tools, features a Y2 axis that permits simultaneous front and back machining using a back tool post and an opposite tool post. The back tool post capacity has been expanded from previous versions. It contains eight tools (two rows of four), and machines complex features on the back spindle. The opposite tool post holds six tools (two rows of three).
Also included are pinch-turning and pinch-milling operations, achieved by the simultaneous use of the back tool post and opposite tool post. A whirling attachment can be added for one-step production of threaded parts up to 0.5 in diameter.
The tool posts have overlapping operations that move synchronously to reduce downtime: one tool post begins an operation before the other fully retracts.
Similarly, during tool replacement or thread cutting an axis movement begins before a previous axis movement ends, which also reduces machining time.
Citizen, in fact, maintains that operators can achieve significant cycle-time reductions on parts depending on machine setup, tool selection, and operation.
There are two spindles and three rotary tools on the machine. The front spindle runs at 10,000 rpm, and has a maximum machining length of 200 mm. (Maximum machining diameter is 20 mm.) The back spindle runs at 8,000 rpm. The gang rotary tool spindle and back tool-post rotary tool spindle each turns at a maximum 5,000 rpm, while the front rotary tool spindle operates at a maximum 7,500 rpm.
The machine can be set up in different tooling configurations, and operators have access to a range of end-face rotary and cross-rotary tools, which increases the complexity of shapes they can machine. Shufelt says engraving is a machining option on parts up to 32 mm.
The unit has direct spindle indexing, which also saves time by categorizing the location where the rotating axis decelerates and stops as the zero point. The unit is designed to minimize vibrations from acceleration and deceleration of cutting tools.
The Cincom L20X also contains an integral bar loader, which Shufelt says acts as a ninth axis.
The machine uses a Mitsubishi Meldas control.