The load-bearing capacity of the rack and pinion is stronger than that of the ball screw and can work under high loads and heavy loads. The rack and pinion can carry a maximum load of 15-20 tons.
The positioning accuracy of the rack relative to the ball screw is not so high.
The rack and pinion design may compromise the overall accuracy of the machine. Factory-produced gears cannot produce the resolution or tolerances of ball bearings. This is why when you look at any industrial machinery, you will find that the most critical axis (Z-axis) has a ball screw.
Recirculating ball bearings can be used in all linear guide systems and are trusted technology from high-end CNC router machines to high-end aerospace and metalworking router centers. Your CNC router should have the same technology so that you can work with the most advanced and accurate system.
The moving speed of the rack and pinion is not as fast as the ball screw.
Ball screws can move quickly, but in simple terms, rack and pinion systems can usually provide greater linear speeds, usually with large amplitudes. If you want to shorten the cycle time, the limitations of the ball screw will only get worse as the length increases.
There are requirements for the rack and pinion installation, clearance must be reserved, and reverse gear gauges are required for installation.
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Rack wear needs to be compensated, and ball screw wear needs to be adjusted.
The ball screw system improves the level of wear. The ball screw on the table of our CNC router machine consists of a sealed bearing and many recirculating ball bearings, which are evenly distributed and continuously lubricated when passing through the channel design.
Rack and pinion do not have this technology, but the gear meshes with the track without lubrication (metal-to-metal contact). You must manually apply grease to the track, otherwise, you will be contaminated by dust, dirt, and other debris when cutting. This reduces lubrication and increases the wear of the gears and their tracks. As time goes by, the gear/rack starts to wear and the tooth pitch further increases (increased clearance), which ultimately changes the overall accuracy of the table. This is caused by the rack and pinion system having to stop at the same point (teeth) over and over again. Our ball screw design does not have this problem, because many of the ball bearings of the ball screw have an unlimited number of contact surfaces that can be parked on.
The rack is easier to manufacture than the ball screw.
Rack-and-pinion is cheaper than ball screws. Generally, it is economical to choose a rack and screw for precision.
As the length increases and the requirements for force increase, precision ball screws become more and more expensive, especially when custom end machining or modification of the nut is required, or when the size needs to be increased to reduce tension or buckling force.
On the other hand, the rack and pinion can provide a high level of positioning accuracy at a relatively reasonable cost. The complexity of manufacturing components is much lower, and longer performance can be more reliable.
Since almost every ball screw application requires a custom length and end finishing, the lead time can be very long. It is not uncommon to spend weeks to tens of weeks to obtain a customized ball screw assembly.
On the other hand, rack and pinion systems can usually be delivered from stock components, and only the last piece of the rack in the system needs to be simply cut.
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