The hottest Swiss cutting technology and its appli

2022-08-12
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Swiss cutting technology and its application

with the development of modern high-tech industry, 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 processing demand characterized by "small, precise and difficult" is a new challenge to the manufacturing industry, which is called "Swiss processing", and its development momentum is very rapid in recent years. In the United States, the sales of tool and equipment manufacturers serving this kind of processing increased 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. Focusing on Swiss cutting technology, this paper comprehensively introduces the application of Swiss cutting tools and processing technology by some foreign tool companies

nowadays, the majority of parts processing plants have become accustomed to the continuous bad news about the manufacturing industry: such as declining sales, layoffs, increased external competition, and so on. However, in the field of precision manufacturing, the situation is quite the opposite: the operation of processing plants shows a strong momentum. Some people claim that this phenomenon is an irreversible development trend of metal cutting and processing 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

for this type of tools and manufacturing technology, the most important thing is to highlight the word "small". It is not enough to describe this kind of machining only with strict tolerance. Steve Barani, the foreman of Remco Swiss, said, "inaccurate tools cannot be used in this kind of processing. For example, a tolerance of 0.125mm is not enough." Vince robisch, President of the company, believes that a tolerance of 0.125mm is completely unacceptable

to illustrate his point, President robisch introduced a micro screw with a diameter of 1.575mm. The screw is made of beryllium bronze rod. 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 way to process small parts, and other types of machine tools are not competent. This processing has the following two characteristics: (1) there is a fixed guide sleeve; (2) There is an axially movable front apex seat. Different from the ordinary lathe, the Swiss machining lathe moves along the Z axis by the workpiece, and the cutter 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 to the guide sleeve of the machine tool as possible, generally 0.635 ~ 1.016mm. The specific size depends on the diameter of the workpiece. When the diameter is small, the distance should be shorter

robisch president believes that during processing, the fixed guide sleeve and the tool close behind it -- the tool must not be far away from the guide sleeve. When these two conditions are combined, high accuracy can be achieved. The head frame of the machine tool moves back and forth with the bar, so that the workpiece can be cut by the tool

Bill Cox, President of Cox manufacturing company, pointed out that on the one hand, the guide sleeve is very important for Swiss processing, but on the other hand, it also brings many problems. This is due to the change of the length diameter ratio of the workpiece. This phenomenon is particularly prominent when using shaped bar materials (such as square and hexagonal sections). When the formed bar is running in the guide sleeve, the non-uniformity of turning is more serious than that of the fixed head frame machine tool without guide sleeve

selection of mechanical and numerical control machine tools

Swiss machine tools for machining can be divided into cam type and numerical control type. Cam type machine tools can be subdivided into two types: one is the ordinary "workpiece rotating type", and the other is the "workpiece fixed type", which is a screw feed type lathe in which the tool rotates around the workpiece

in Remco company, the number of workpiece rotary cam machine tools is far more than expensive CNC machine tools, and the number is about 4:1. At the same time, like many Swiss processing plants, Remco tends to use special tools and special cams. Robisch, the president of the company, said that we do not use ready-made general tools. When we receive an order for a new part, we design special tools, which only serve this part. After completing the task, save the tool. The next time similar parts need to be processed, there is no need to redesign the tool, and users do not have to pay for the tool

Cox manufacturing company believes that the reason why the cam manufacturing process is still very applicable and viable is that 20 years ago, manufacturing a group of cams with the old process was 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 function of cam machine tools

dave branvold, the foreman of bay Swiss manufacturing company, pointed out that the characteristics of Swiss machining tools, in addition to being small, also need to have a large back angle to reduce the cutting pressure, so that the tool will not bear too much friction. Otherwise, the bar may get stuck in the guide sleeve. The second feature of this tool is the need for a positive rake angle. Until recent years, people did not use indexable blades because they could not meet the above requirements, which forced processing plants to grind suitable blades with cemented carbide blanks by themselves. Now, due to the improvement of the structure and performance of indexable blades, 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 cemented carbide tools to grind a suitable angle by themselves. Branvold, robisch and Cox manufacturing companies all stressed that they need special tools in processing. Cox manufacturing company believes that our cutting tools are specially ground for specific purposes

David wills, technical manager of stellam tools, understands the above situation. He said, "we have always maintained contact with this processing field. As a professional factory from Europe, our advantage is in small-scale turning processing. The company has been seeking to help users in appropriate fields: if users can't solve problems in other tool suppliers, we are willing to cooperate with them and provide services. Our R & D department will help them improve quality and shorten working hours."

for tool suppliers, the strongest growth of Swiss tools is in the field of NC machining. The difference between numerical control machine tools and cam type machine tools in Swiss machining is that coated indexable blades are mainly used as cutting tools. Cox manufacturing company claims that in Swiss CNC machining, we mostly use indexable blades

Dick reiling, President of micro mathematics, pointed out that he did not think that one day all craftsmen engaged in Swiss processing would stop making their own knives. But he admitted that we are trying to use indexable tools as much as possible. Although they are expensive, they are easy to replace after tool wear, with little labor loss

the market is growing

what force makes Swiss processing continue to grow? David wills, technical manager of stellam tools, believes that this is the development of Swiss processing driven by the high-tech industry. With the development of small size and light weight of parts, the use of unconventional materials is also increasing, and the accuracy requirements are also very high. Some Swiss processing equipment suppliers said that their business volume has increased by 45-50% in the past two years, while any other machine tool supplier is unlikely to achieve a 50% growth in two years

Raymond Koontz, vice president of centary tools and design, agrees. He believes that the demand in the high-tech field, especially the demand for precision stainless steel parts in the computer industry, is one of the biggest reasons for the growth of Swiss processing

for example, on a two-way contact switch, two parts can be used as representatives of many parts made by Swiss processing. One is the titanium alloy plug-in for the root channel, and the other is the steel needle valve of the hydraulic system. They are characterized by thin, long and precise parts. The inner diameter tolerance is required to be 0.01mm, and the outer diameter tolerance is required to be 0.0076mm

in factories equipped with Swiss screw lathes, the batch production of the above similar parts is 1000 ~ 500000, sometimes larger. The working time of a single piece is as low as 6.5 seconds. This Swiss processing is generally carried out in specialized factories, and 90% of the allowance is usually cut off at the first cutting. The advantage of this is that it can maintain concentricity in the processing of long workpieces, and omit finishing processes such as grinding

however, there are conditions for the quality of Swiss processing to reach a high level: first, the workpiece blanks and bars should be round and uniform. If the bar material has deviation, it will be reflected on the workpiece. Therefore, the copper, steel and stainless steel bars produced according to Swiss quality standards have tightened tolerances and meet the requirements of uniformity. However, cold drawn bars with Swiss quality standards are not available from stock. The roundness of ordinary cold drawn steel can be ensured by adding a surface removal grinding process. In this way, the cost will increase by 15% - 20%

lombord Swiss screw is a Swiss style processing plant. It turns red copper, brass, phosphor bronze, aluminum, lead containing steel, easy cutting steel, 300 and 400 series stainless steel and nickel chromium molybdenum alloy (8620s), etc. Bernie Seewald, President of the company, found that the tool life changes with the workpiece finish requirements, and the impact of material changes is greater. For example, when a tool is used to process the same parts, it can cut 2000 pieces when the material is stainless steel, 3000 ~ 4000 pieces when the material is easy to cut red copper, and 20000 ~ 50000 pieces when the material is brass. Seewald said, "because 303 and 416 series stainless steel are difficult to cut, we use carpenter project70 series stainless steel, which is relatively easy to cut. The tool is generally micro 100 cemented carbide brazing tool, and the angle is polished with diamond grinding wheel. In addition, it is also because in most states, the content returned by Google should better meet the needs of users, and the indexable blade with tin coating is used."

the service life of the tool is also related to the structural design of the workpiece. For example, when machining right angle shoulders and corners, the tool life is lower than when machining rounded corners. For machining right angle parts of some materials, the tool life is only 1000 pieces

since the motorized feed of Swiss machining is left-hand, all kinds of tools, including drill bits and reamers, must be left cutting. This makes the cutting tool an unconventional variety. For example, the left cutting reamer has no stable spot supply, and the user factory has to make it by itself

in Swiss machining, we must also pay attention to the interaction between tools and workpieces, and between workpieces and machine tools. For example, although using the built-in guide sleeve of the collet in machining is helpful to turning long parts, the influence of thermal expansion becomes a problem when machining small-diameter parts because the thermal conductivity of the cutting area is limited. Therefore, the cutting speed should be limited so as not to generate too much heat and weld the workpiece into the guide sleeve. For example, when machining parts with a diameter of 3.175mm and a length of 50.8mm, the cutting speed must be below 27.4m/min

in Swiss machining, although new machine tools are CNC, it is estimated that the integration of convex Izumi aiming system and multi material machining system wheel machine tools still account for 60 ~ 70%. Even CNC machine tools are used to process small parts. Generally, the maximum diameter of bars is not more than 31.75mm. Too large bar material will cause difficulty in loading and unloading. For example, the blank with a diameter of 50.8mm and a length of 3658mm is difficult to load and unload due to its bulkiness. in addition

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