SFU industrial ball screw and DFU ball screws have significant differences in structure, performance, application and other aspects, the following from the core dimensions to start a comparative analysis:
I. Structural design differences
SFU industrial ball screw: belongs to the standard type of ball screw, the screw shaft and the nut are equipped with a circular arc-shaped raceway, and the ball rolls in the raceway to realize the motion transfer. Nut built-in reverser to guide the ball circulation, common external circulation structure, through the pipe or spiral groove return pipe, so that the ball in the completion of a period of travel back to the starting position, the structure is relatively simple, easy to maintain and manufacture.
DFU Ball Screws: Usually adopts the unique design of internal circulation structure, with the inlay of reverser inside the nut, so that the ball is circulated directly in the nut, without external return pipe. This design makes DFU Ball Screws more compact, the outer diameter of the nut is smaller, occupies less space, and the ball circulation path is short, which reduces the collision and friction when the ball moves.
Comparison of Performance Parameters
Transmission Efficiency: SFU industrial ball screw adopts external circulation design, and there is a certain loss of movement of ball in the process of reflux, and the overall transmission efficiency is about 90%-94%; DFU ball screw reduces the friction between ball and reflux pipeline due to the internal circulation structure, so the transmission efficiency is higher and can reach 92%-96%, which is obvious and can effectively reduce energy consumption in high-speed running condition. It can effectively reduce energy consumption.
Motion accuracy: SFU industrial ball screws are affected by the external circulation structure, which may cause small vibration when the ball is circulating, and the positioning accuracy is generally ±0.01-±0.02mm; DFU ball screws have an internal circulation structure to make the ball movement smoother, and the positioning accuracy can be up to ±0.005-±0.01mm, and the repetition accuracy is higher, which is more suitable for precision machining scenarios that have stringent requirements on accuracy. It is more suitable for precision machining scenarios with strict requirements on accuracy.
Rigidity and loading capacity: SFU industrial ball screw's outer recirculation structure makes its nut size larger and its rigidity better, which can withstand larger radial and axial loads and is suitable for heavy-duty working conditions; DFU ball screws have a compact inner recirculation structure and relatively thinner nut thickness, which makes its rigidity slightly inferior to that of SFU ball screws, but by optimizing the design of the raceway and the way of preloading, some of the models can meet the demand of medium and high loads. However, by optimizing the raceway design and preloading method, some models can also meet the needs of medium and high loads, and the dynamic response speed is faster.
Running noise: SFU industrial ball screw's external circulation ball will produce some collision when it moves in the return pipe, and the running noise is about 60-65dB; DFU ball screw's internal circulation structure makes the ball movement smoother, and the running noise can be controlled at 55-60dB, which is more suitable for noise-sensitive environments, such as medical equipments and electronic manufacturing workshops.
Cost and Maintenance Differences
Manufacturing Costs: SFU industrial ball screws have mature manufacturing process and low production difficulty, which makes the cost relatively controllable and the price of the product friendly; DFU ball screws require higher precision of the reverser and nut machining process due to the internal recirculation structure, which increases the manufacturing cost by about 20%-30% and leads to high selling price of the product.
Maintenance: The external circulation structure of SFU industrial ball screw facilitates the inspection and replacement of ball and return pipe, and the maintenance is relatively convenient, but it is necessary to clean the impurities in the return pipe regularly; the internal circulation structure of DFU ball screw has good sealing, and the ball is not easy to be contaminated by the outside world, and the lubrication cycle can be prolonged by 20%-30%, but in case of a malfunction, it is more difficult to maintain the internal inverters and ball screws, and it is usually necessary to return to the lubrication center. However, in case of failure, the internal reverser and ball screws are difficult to repair and usually need to be returned to the original factory for processing.
Four, the difference between the applicable scene
SFU industrial ball screw: commonly used in automated production lines, ordinary CNC machine tools, packaging machinery and other cost-sensitive, large load but moderate precision requirements of the equipment. For example, in the automated assembly line of automotive parts, SFU screws can carry the weight and inertia of the arm with high rigidity to ensure stable operation.
DFU high precision lead screw: It is suitable for semiconductor lithography, precision coordinate measuring instrument, medical CT equipment and other high-end equipment with high precision, high speed and low noise requirements. In semiconductor lithography, DFU Ball Screws ensure the precise displacement of the wafer platform during the lithography process by virtue of its micron-level positioning accuracy and fast dynamic response, thus ensuring high precision in chip manufacturing.
✅ Precision Manufacturing
SFU screws adopt external loop structure, with positioning accuracy up to ±0.01mm after double nut preload, and the surface roughness of the parts can be optimized up to Ra1.0μm, which meets the general machining requirements. DFU ball screws, by virtue of the internal loop design, have a high positioning accuracy up to ±0.005mm, with surface roughness as low as Ra0.8μm, and the effect of tool life extension is even better, which is suitable for high-precision machining in aerospace and other industries. Precision machining.
✅ In the automated production line
3C high-speed mounting, SFU screw realizes ±0.01mm repetitive positioning with an operating efficiency of 5000 times/hour; DFU ball screw achieves ±0.008mm repetitive positioning accuracy with an efficiency of 6000 times/hour and a higher yield rate. When press-fitting automobile parts, SFU screws can withstand 4000N impact force and DFU ball screws can withstand 5000N, with less wear and 30% higher reliability.
✅ Extreme environment
Under the environment of -55℃~+125℃, SFU screws' low-temperature starting resistance increases by ≤20%, and low-temperature efficiency decreases to 85%; DFU ballscrews' starting resistance increases by ≤15%, and the transmission efficiency maintains above 90%, which is more adaptable to the harsh environment.
✅Medical and food machinery
In medical field, SFU Screws can meet Class 6 cleanliness standard, and DFU Ball Screws can reach Class 5, with higher cleanliness. In food production, SFU screws can be rust-free for 800 hours, and DFU Ball Screws can be corrosion-free for 1000 hours by virtue of the advantage of internal circulation, which is more hygienic and safe.
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