Start from the application, not only the grade
C7 and C5 mainly describe accuracy grade. Buyers should confirm machine use, travel, speed, load, budget, and lead time before choosing a higher accuracy option.
When C7 is usually enough
C7 rolled ball screws are often suitable for standard equipment, repair replacement, distributor stock, packaging machinery, and general automation where cost and delivery matter.
When to consider C5
If the machine needs higher positioning accuracy, repeatability, and running stability, or if the original drawing specifies C5, discuss a ground ball screw with clear inspection requirements.
- Send diameter, lead, overall length, and thread length.
- Describe machine type, travel, speed, and load.
- Confirm nut type, preload, or backlash requirement.
- Attach support model or end drawing when machining is needed.
Typical buyer situations
This topic usually appears in distributor stocking, repair replacement, machine retrofit, automation projects, and drawing-based purchasing. If a buyer sends only one model number, the supplier cannot judge the real use, packing risk, or whether machining upgrades are needed.
Details to confirm before quotation
To reduce repeated questions, the RFQ should cover product specification, use case, and delivery expectations together. The following points can be copied into the RFQ form or email.
- Purchase purpose: distributor stock, repair replacement, machine project, or sample testing.
- Specification: diameter, lead, overall length, thread length, nut type, and quantity.
- Machining: cut-to-length, end machining, and whether BK/BF, FK/FF, EK/EF, or other supports must be matched.
- Delivery: target quantity, expected lead time, packing, labels, shipping method, and whether shipment photos are required.
Common mistakes
A common mistake is asking only for unit price without application, quantity, or packing details. Another is sending photos without dimensions. This turns quotation into guesswork and can create errors in end machining, nut matching, or long-part shipping.
Next step
If the specification is clear, submit an RFQ directly. If the model or accuracy grade is still uncertain, describe the machine use and old part details so the supplier can recommend a standard part, bar stock, cut-to-length, or end machining route.
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