Which is better between hard rail and linear rail in CNC machining center?
Posted by Admin
Generally, if the CNC machining center is used to make products, it will buy the line rail. If it is used to process the mold, then buy the hard rail. The precision of the line rail is higher than that of the hard rail, but the hard rail CNC machining center is more robust and durable.
Hard Track Features
The benefits of hard rail cnc machining center:
1. Able to accept larger loads, suitable for roughing machine tools with large tool volume and large feed.
2. Due to the large contact area of the guide rail, the operation of the machine tool is more stable, and it is suitable for machine tools with high requirements for machine tool oscillation, such as grinding machines.
Disadvantages of hard rail cnc machining center:
1. The material is not uniform. Because it is generally cast, so casting defects such as sand inclusion, air holes, and looseness are likely to occur in the material. If these defects exist on the guide rail surface, it will have a very unfortunate impact on the service life of the guide rail and the accuracy of the machine tool. .
2. It is difficult to process. Because this type of guide rail is generally connected with the main components of the machine tool such as base, column, worktable, slider, etc., in the process of processing, its shape and position, roughness and excess requirements are required. The aging treatment, quenching treatment and other processes are difficult to control, and then the processing quality of the parts cannot meet the requirements of the equipment.
3. The equipment is difficult. The word "equipment" means that it needs to be assembled and equipped, and the process of matching is a process of combining skills and physical strength, which cannot be completed by ordinary workers. The relative number of skills required , The equipment and workers who have a proper grasp of the overall accuracy of the machine tool are adjusted, and at the same time, they also need to be equipped with a shovel, a flat ruler, a square ruler, a square ruler, a dial indicator, a dial indicator and other corresponding tools.
4. The service life is not long. This can only be relatively speaking. Under the same maintenance and use conditions, the service life of a wide range of hard rails is less than that of the linear rails, which is related to their movement methods. A great relationship, the hard rail is sliding and colliding, while the line rail is rolling and colliding. From the perspective of the resistance, the resistance of the hard rail is far greater than that of the line rail, especially In the case of insufficient smoothness, the resistance of the hard track is even worse.
5. The repair cost is too high. The repair of the hard rail is far greater than the repair of the line rail in terms of difficulty and repair cost. Assuming that the shovel allowance is lacking, it may involve dispersing all the large parts of the machine tool. , re-do quenching treatment and machining, or even re-cast the large piece, and the wire gauge only needs to replace the corresponding wire rail, which basically will not greatly affect the use of the relevant large piece.
6. The operating speed of the machine tool is low, and the hard rail generally cannot accept too fast operating speed due to its movement method and the accepted resistance force, which is definitely contrary to the current processing concept. In particular, many factory workers do not have the corresponding maintenance knowledge of machine tools. In many cases, they only know how to use machine tools, but largely ignore the maintenance of machine tools. The maintenance of machine tool tracks is the top priority. Once the track is not smooth enough, It will cause track burnout or wear transition, which is a serious damage to the accuracy of the machine tool.
The benefits of line rail cnc machining center
1. The cnc machining center is simple and convenient, and high-quality equipment can be completed with a little practice. Because the precision of the CNC machining center machine tool is very high, the degree of accuracy determines the accuracy of the transmission arrangement. The transmission arrangement is generally composed of a wire rail and a screw rod, that is to say, the accuracy of the wire rail and the screw rod itself determines the accuracy of the machine tool, while the wire rail And the lead screw generally exists in the form of standard parts, you only need to select the corresponding precision provided by the manufacturer, and generally there will be no major problems.
2. There is a lot of room for selection, whether it is from the structure method of the rail or the accuracy level, the smooth method or the load-bearing capacity, the processing method to the working speed and other parameters can be selected, you can choose according to the specific situation of the machine tool you plan, Arbitrarily configure the type of track you need.
3. The operation speed is fast. Now many machine tools operate extremely fast, especially the idle speed. This is largely due to the credit of the line rail. Due to the rolling and conflicting operation method and high-precision processing, it is truly guaranteed. The accuracy and stability of the high-speed operation of the machine tool greatly improve the processing power and processing accuracy.
4. High machining accuracy. As a standard product, both the material and the processing method have entered a benign and controllable scale. Therefore, most of the machine tools in the field of finishing use high-precision line The rail is used as a machine tool guide, which also greatly ensures the machining accuracy of the machine tool. The Nanjing technology, the Hanjiang line rail, Taiwan has the Shangyin line rail, the German Rexroth company, Japan has the THK line rail, etc. , These brands are extremely rich and meet the needs of the shopping malls for various requirements of the rails. Personally, I like to use the Japanese THK, which is stable in function and precise in workmanship, but the price is on the high side.
5. The service life is long. Because the working method of the line rail is rolling interference, the steel ball in the slider drives the movement of the feeding part through rolling on the track. The resistance received by this rolling interference is smaller than that of the hard rail. Therefore, whether it is the transmission power or the service life, the wire rail should be much more ideal than the hard rail.
6. The repair cost is low. Whether it is in terms of repair cost or repair convenience, the line rail has its natural advantages and convenience. Because as a standard part, the replacement method of the line rail is the same as replacing a screw. Yes, of course there are some recovery adjustments in accuracy, but for a hard track, it's really convenient.
7. The delivery cycle is short, and the general delivery cycle of line rails can be completed within half a month, unless you choose foreign brands, such as Rexroth and THK. In fact, these two brands also have corresponding processing plants in China. , as long as the type of rail you choose is not very biased, basically the delivery period of about half a month can still be guaranteed, and the rail of Taiwan Shangyin can even achieve a one-week delivery period, but The same hard track does not have such a good time to control the talent. If the action is relatively large, such as recasting, the cycle may be more than a few months.
Disadvantages of wire rails
1. The carrying capacity is relatively small. This relatively small size is only for hard rails. In fact, after some structural planning of the line rails of many large factories, the carrying capacity has been greatly improved. Of course, it is relatively hard. In terms of the carrying capacity of the rail, it is still relatively small.
2. The stability is relatively weak compared to the hard rail, such as the ability to resist oscillation, etc., but I still want to emphasize that this weakness is relative to the hard rail. In fact, the stability of many line rails is also It's done very well, as long as the equipment you plan is not overly special, and generally can meet the needs.
3. Special attention should be paid to the maintenance of the line rail during transportation and equipment. As a standard part, its unique structural characteristics make it in an embarrassing situation where it is relatively easy to be damaged, such as slender shape and lead to line The rigidity of the rail is lacking, and it is easy to bend and deform when it is kneaded, and then lead to the loss of accuracy; for example, because it is a steel part, if no anti-rust treatment is done, it will come into contact with water or other solvents during transportation and equipment. Phenomena such as rust and corrosion easily occur, and then lead to loss of accuracy.