With the development of modern high-tech industries, especially the IT industry, the emerging manufacturing industry represented by the computer industry, its parts are increasingly developing in the direction of small size, light weight and high precision, and the use of special materials is also increasing. This kind of processing demand characterized by “small, precise and difficult” is a new challenge to the manufacturing industry and is called “swiss lathe machining“. In recent years, the development momentum has been very rapid. In the U.S., tool and equipment manufacturers serving this process have seen sales increase by 50% in two years. It should be noted that this development trend is not only a challenge to the machine tool industry, but also a new opportunity. This article is centered on Swiss cutting technology and comprehensively introduces the application of Swiss cutting tools and processing technology by some foreign tool companies.
Nowadays, the vast number of parts processing factories have become accustomed to the bad news about the manufacturing industry that has been coming: such as declining sales, laid-off employees, and increased foreign competition. However, in the field of precision manufacturing, the situation is diametrically opposite: the operation of processing plants is showing strong momentum. Some people claim that this phenomenon is an irreversible development trend in the metal cutting and cnc swiss machining industry. These trends include: a wide variety of small parts, precision tool technology and “mass production to order”. In response to this demand, Swiss cutting technology has been developed. The most important thing for this type of tool and manufacturing technology is to highlight a “small” word.
It is not sufficient to describe such processing with strict tolerances. Steve Barani, foreman of remco swiss, said: “Inaccurate tools cannot be used in this kind of machining. For example, a tolerance of 0.125mm is not enough.” The company’s president, Vince Robisch, believes that a tolerance of 0.125mm is not enough. To illustrate his point of view, President Robisch introduced a miniature screw with a diameter of 1.575mm as an example. The screw was made of beryllium bronze bar. When turning the screw, the tool should be close to the guide sleeve, and the distance should not exceed 0.508～0.635mm, otherwise the material will be bent. Robisch believes that the Swiss turning method is the only method for machining small parts, and other types of machine tools are not competent.
This processing has the following two characteristics:
- (1) With fixed guide sleeve;
- (2) There is an axially movable front center seat.
The difference with ordinary lathes is that the movement of the Swiss-type machining lathe along the z-axis is performed by the workpiece, and the tool moves radially along the x-axis. In addition to the structural shape of the tool and workpiece, an important aspect of maintaining accuracy is that the contact of the tool/workpiece should be as close as possible to the machine tool guide sleeve, which is generally 0.635 to 1.016 mm. The specific size depends on the diameter of the workpiece. If the diameter is small, the distance should be shorter. President Robisch believes that in the processing, the fixed guide bush and the tool next to it-the tool must never be far away from the guide bush. When these two conditions are combined, high accuracy can be achieved. The headstock of the machine tool moves back and forth with the bar stock, so that the workpiece is cut by the cutter.
Zouhanpin, president of PTJ Manufacturing, pointed out that on the one hand, the guide bush is essential for Swiss machining, but on the other hand, it also brings a lot of problems. This is due to changes in the aspect ratio of the workpiece. This phenomenon is particularly prominent when using shaped bars (such as square and hexagonal cross sections). When the shaped bar is running in the guide bush, the unevenness of turning is more serious than the fixed head frame type machine tool without guide bush. Choice of mechanical and CNC machine tools Swiss-type machining machine tools can be divided into two types of cam and CNC. Cam-type machine tools can be subdivided into two types: one is a common type “workpiece rotating type”, and the other is a “workpiece fixed type”, a screw feed lathe with tools rotating around the workpiece. At PTJ, the number of rotating cam machine tools for workpieces is far more than expensive swiss CNC machine tools, and the number is about 4:1. At the same time, like many Swiss processing plants, PTJ tends to use special tools and special cams. The company’s president David claimed that we do not use off-the-shelf general-purpose knives. When we receive an order for a new part, we will design special knives that will only serve this part. After completing the task, save the tool. Next time when similar parts need to be processed, there is no need to redesign the tool, and the user does not have to pay for the tool. The PTJ manufacturing company believes that the cam-type manufacturing process is still very suitable and has vitality because the manufacturing of a group of cams using the old process 20 years ago is neither accurate nor expensive. Today’s cams are designed with special software and processed on CNC machine tools, which is both accurate and economical. It can be said that CNC technology improves the functions of cam machine tools. Dave Branvold, the foreman of bay swiss manufacturing company, pointed out that in addition to the small size, the characteristics of Swiss machining tools also need a larger clearance angle to reduce the cutting pressure and prevent the tool from bearing excessive friction. Otherwise, the bar stock may get stuck in the guide sleeve. The second feature of this tool is the need for a positive rake angle. Until recently, people did not use indexable inserts because the above requirements could not be met, which forced the processing plant to grind suitable inserts by using carbide blanks. Now, due to the improvement of the structural performance of indexable inserts, the use has been increasing. The situation mentioned by branvold is not an individual phenomenon in Swiss processing. Many processing plants believe that the easiest way is to use brazed carbide tools to grind out the proper angle by themselves. Branvold, Robisch and Cox manufacturing companies all emphasized that they need special tools for machining. ptj manufacturing company believes that our knives are specially ground for specific purposes. david wills, technical manager of stellram tools company, understands the above situation. He said: “We have always been in contact with this processing field. As a professional factory from Europe, our advantage is in small turning. The company has always sought to help users in the appropriate field: if the user is in other tools Suppliers can’t solve the problem, and we are willing to cooperate with them to provide services. Our R&D department will help them improve quality and shorten working hours.”