Fixed-Headstock Automatic Lathe SK-51 Newly Released

A fixed-headstock automatic lathe for large diameter machining to complement the product lineup

Star Micronics Co., Ltd. has developed SK-51, a new model of the fixed-headstock automatic lathe (Note 1) following the introduction of SG-42 in 2011. Having the maximum machining diameter of 51 mm -the largest in our lineup- the new model aims to serve large diameter machining needs for such industries as automotive and construction. The product is scheduled to launch in July 2019.

The SK-51 is equipped with two spindles, each for front and back machining. Along with its multiple tool posts, it is constructed for optimized processing of large workpieces of complex shape. What is being released this time are two types, Type A, and Type D.

Type A is the version which has two 12-stationed turret-type tool posts with each and all the stations capable of mounting a power tool unit to enable the same level of multi-processing on both the front and back sides. Type D is the model of the highest end which has a total of three tool posts consisting of two 12-stationed turret-type tool posts and one 4-stationed turret-type tool post with B-axis control to enable even more diverse processes such as slant machining or simultaneous 5-axis processing. The modular design approach applied to this model is expected to extend further to the future product lineup to meet a variety of needs from the market.

The slanted bed design employed by the machine base reduces the distance from the front side of the machine to the spindles while the wide opening sliding door of the cutting chamber provides easy access to the spindles and the tool posts. The NC system is equipped with the program check function by 3D simulation before actual cutting. Also, the touch type control panel with the large display can be swiveled to improve the workability and operability of the operator.

With the upcoming launch of the SK-51, the company aims to expand the sales in the fixed-headstock automatic lathe segment to increase the share in the machine tool market along with the existing Swiss-type automatic lathe series (Note 2).

Features of SK-51

[High Functionalities]

• Type A is equipped with two 12-stationed turret-type tool posts with 3-axis (X/Y/Z) control. Each and all stations can be mounted with a power tool unit such as milling or front-drilling unit.
• Type D has a total of three tool posts consisting of two 12-stationed turret-type tool posts and one 4-stationed turret-type tool post with B-axis control to enable even more diverse processes.
• The 4-stationed turret-type tool post with B-axis control is capable of simultaneous 5-axis processing on both the front and back sides.
• Main and sub spindles can be mounted with optional power chuck for added flexibility in multi-processing of the cast or forged workpieces.

[High Rigidity and Accuracy]

• The slide of the X-axis of each tool post adopts the square type slide guideway structure to ensure the rigidity of the post.
• The power tool of the 12-stationed turret-type tool post is designed with one position drive mechanism which reduces heat generation to minimize the dimensional change.
• The model comes with the highly accurate and flexible thermal displacement correcting system based on the thermal data fed from multiple locations of the machine.

[Workability and Operability]

• Adoption of slanted bed design for the machine base reduces the distance from the front side of the machine to the spindles for improved workability for the operator.
• The door of the cutting chamber slides wide open to the operator’s knee zone to offer ample space for setups and other works.
• The NC system is equipped with the program checking function by 3D simulation to verify the program prior to the actual machining.
• The swing type control panel mounted with a large (15-inch) touch panel display enhances operability.

NOTE 1: Fixed-Headstock Automatic Lathe

Unlike the sliding head-type (Swiss-type) automatic lathe which has the headstock move along the axial direction with the workpiece clamped, the fixed-headstock automatic lathe is constructed to have the tool post move along the axial direction like general-purpose lathes.
In the fixed-headstock automatic lathe, the workpiece is clamped at its tail with its full length exposed. This structure is unsuitable for the processing of thin and long workpieces due to the material flexure by the processing load, but suitable for the processing of thick and short workpieces that do not flex. The other benefit is that the fixed-headstock lathes can reduce the stock waste to optimize the use of raw material while the sliding head-type lathes cannot avoid the length of guide bush to remain unprocessed as stock waste.

NOTE 2: 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.