Swiss Type Automatic Lathe SB-16R/20R type G Newly Released

SB Series Equipped with Guide Bush/Non-Guide Bush Switching Function

Star Micronics has developed SB-16R/20R type G for a maximum machining diameter of φ16mm and φ20mm each as renewed Swiss type automatic lathes (Note 1) in the SB series. These models will be launched in June, 2014 and are designed for the machining of parts mainly used in the automobile, information & communication equipment and medical care industries.

Since the release of the initial model, SB-16, in 2003, a total of more than 6,000 units in the SB series has been sold. The SB series is a best-selling model for Star. The SB-16R/20 type G with a 7-axis control function enables switching between the guide bush type and non-guide bush type (Note 2). When handling motor shafts and other long parts, the guide bush type is able to function as a steady rest for the material to regulate the material deflection. On the other hand, the non-guide bush type can be used for nuts and other short parts. By minimizing the length of residual materials, the material cost can be reduced and the best machining for the parts is achieved.

The gang-type tool post employs a Star original slanted slide guideway structure (Note 3), as in the conventional SB series, to enhance the machine rigidity and achieve continuous machining with stable accuracy.

The NC unit has a variety of help functions, such as an alarm help function to monitor alarm contents on the NC screen. In addition, a swing-type operation panel enables machining at an optimum position to improve operator’s control and workability.

Features of SB-16R/20R type G

• Either the guide bush type or the non-guide bush type can be selected according to the total length of parts to machined.
• There are four options available for power tools to be mounted on the gang-type tool post: a 4-spindle-type cross drill unit, 5-spindle-type cross drill unit, 5-spindle-type cartridge cross drill unit and 5-spindle high-speed-type cartridge cross drill unit.
• When the 5-spindle-type or 5-spindle high-speed-type cartridge cross drill unit is mounted, a variety of tool units can be combined at three cartridge positions.
• The 4-spindle-type unit especially designed for back working is able to readily accommodate a tool rotation drive unit. This enhances functions of complex machining, including eccentric hole drilling, slotting, etc. on the rear end.
• The main spindle incorporates a built-in motor to achieve improved indexing accuracy.
• Both the main spindle and sub spindle are equipped with the C-axis control function as standard equipment.

Major Specifications

NOTE 1: Swiss-type automatic lathe

The Swiss-type automatic lathe was devised as watch component processing machinery in Switzerland in 1870s. Known as a “sliding head-type automatic lathe” as well, it has remarkable characteristics of high-precision cutting of components with longer length compared with the diameter.
In general, if long and narrow parts are processed with a general-purpose lathe, flexure will occur on the workpiece, making finishing with the correct dimensions impossible. The Swiss-type automatic lathe utilizes a guide bush to function as a material steady rest. The tool, positioned at a certain distance from the guide bush, gives a cutting motion only the direction of outside diameter. This allows the workpiece to be cut accurately with no flexure. As for axial motion, the headstock, rather than the tailstock, moves while clamping a workpiece.

NOTE 2: Non-Guide Bush Type

This is a sliding head-type automatic lathe which is designed based on the Swiss-type automatic lathe with a guide bush dismounted. Without a guide bush, it is not best suited for machining narrow and long parts. If the workpiece is short and does not deflect without using a guide bush, however, such a material can be handled effectively.
With the Swiss-type automatic lathe, the rear side of the bar material needs to be handled as waste as a portion equivalent to the size of the guide bush structure which functions as a material steady rest cannot be machined. The non-guide bush type reduces the wastes from materials to about 1/3 in length compared to the waste made by the guide bush type.

NOTE 3: Slanted slide guideway structure

The machine main body base and the tool post are slanted and each sliding surface is in a trapezoidal shape, called a dovetail structure. This structure allows each sliding surface to come into contact with its entire plane to improve the machine rigidity. The ball screw center and the cutting point are close to each other to reduce a load (moment load) applied in the direction of torsion caused by cutting resistance.