I. Difference between precision grade and processing standard
C5 grade ball screw bearing housings belong to precision grade, corresponding to ISO P5 tolerance, hole diameter tolerance ±0.005mm, and more stringent form and position tolerance (such as perpendicularity ≤0.01mm/100mm), applicable to high-precision equipment.
C7 level for the general level, corresponding to ISO P7 tolerance, aperture tolerance ± 0.01mm, shape and position tolerance requirements are low (such as perpendicularity ≤ 0.02mm/100mm), applicable to general industrial equipment.
Second, the targeted differences in application scenarios
Typical applications of C5 ball screw bearing block:
It is mainly used in scenarios with extremely high requirements for precision and stability. For example, the spindle part of CNC machine tools, need to withstand more than 10,000 revolutions / minutes of high speed, and at the same time to ensure that the radial runout when the tool rotates ≤ 0.005 mm to ensure that the surface finish of the parts processing; semiconductor equipment drive shaft system, the requirements of low vibration, high-precision positioning (error ≤ 0.01 mm), and need to be coupled with a temperature control system to control the temperature of the bearings.
Common scenarios for C7 class lead screw support bearings:
are mostly used in general-purpose equipment with low to medium speeds (≤3000 rpm) and medium loads. For example, the impeller drive of industrial fans, when the weight of the impeller ≤ 50 kilograms, allowing a certain degree of vibration (vibration speed ≤ 2.8 mm / sec); agricultural machinery, ordinary motors (power ≤ 55 kW) and other scenarios, the installation of low precision requirements, on-site manual assembly to meet the needs of the demand, such as raw material conveyor drive motors in cement factories.
Third, the difference between structural design and materials
Material selection:
C5 grade bearing housing mostly use high-strength cast iron (such as HT300) or alloy cast steel (such as ZG40Cr), high-end scenes will use 7075-T6 aluminum alloy, in order to take into account the strength and lightweight; C7 grade is commonly used in gray cast iron (HT200) or ordinary carbon steel (Q235), the cost is lower.
Structural reinforcement:
C5 grade has more intensive reinforcement design, and some of them will be set with copper alloy bushings in the seat holes to improve wear resistance; C7 grade has a simpler structure, with sparser distribution of reinforcement, and most of them are one-piece cast iron parts.
Seal design:
C5 grade usually adopts double-lip skeleton oil seals with labyrinth seals, with dustproof and waterproof rating up to IP65, which is suitable for clean environments; C7 grade mostly adopts single-lip oil seals or felt seals, with dustproof rating of IP54, which is suitable for dry scenarios.
Installation:
C5 grade needs to be calibrated by laser alignment instrument to ensure the coaxiality ≤ 0.02 mm, often fixed with positioning pins; C7 grade can be manually calibrated (coaxiality ≤ 0.1 mm), and can be fixed with bolts only.
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C7 housings | |
| Material selection | High-strength cast iron (HT300) or alloy cast steel (ZG40Cr), aluminum alloy for some high-end scenes (e.g. 7075-T6) | Gray cast iron (HT200) or ordinary carbon steel (Q235) with lower cost | |
| Structural strengthening | The stiffener design is denser, and the seat hole may have a sleeve structure (e.g., copper alloy bushing) for improved wear resistance | The structure is simple, the stiffeners are sparse, and some of them are one-piece iron castings | |
| Sealed design | Mostly double lip skeleton oil seal + labyrinth seal, dustproof and waterproof grade up to IP65, suitable for clean environment | Single-lip oil seal or felt seal, dust resistant IP54 rating, suitable for dry scenes | |
| Installation: | It needs to be calibrated by a laser alignment instrument (concentricity ≤0.02mm), and it is often fixed with a positioning pin | It can be manually calibrated (concentricity ≤ 0.1mm) and bolted on |
Fourth, the cost and maintenance differences
C5 grade lead screw support bearing due to precision grinding process accounted for more than 40%, the processing cost is higher, the price is usually 2-3 times of the C7 grade; maintenance requires special tools (such as vibration meter, thermal imager), every 500 hours need to test the accuracy, the replacement of bearings should be used to check the seat hole micrometer wear.
C7 class lead screw support bearing mass production cost is lower, casting simple machining can be; maintenance is simple, through visual inspection of oil seal wear, manual grease filling can be, the replacement cycle is up to 1-2 years, suitable for non-critical equipment.
Five, the core principles of selection
according to the demand for precision judgment: if the equipment positioning error needs to be ≤ 0.05 mm or speed> 5000 rpm (such as printing press cylinder), choose C5 level; ordinary power transmission equipment (such as fans, pumps) choose C7 level.
Selection according to the working environment: high temperature (> 120 ℃), high dust scenarios (such as mining machinery), C5 level of sealing and materials are better; room temperature clean environment (such as food production lines), C7 level of cost-effective.
Decision-making by cost budget: Precision equipment (such as medical CT racks) prioritize C5 grade to ensure reliability; general equipment (such as small fans) choose C7 grade to reduce costs.
To summarize, the difference between C5 and C7 bearing housings lies in the balance of "precision, cost and working condition" - the former focuses on precision control, while the latter focuses on economy and practicality, and the selection should be based on the performance of the equipment and the usage scenarios.
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