If a ball nut develops abnormal noise, uneven running torque, excessive backlash, ball loss or visible damage during the warranty period, stop operating the machine and preserve the product in its current condition. Continuing to run or disassembling the ball nut may increase the damage and make the original cause more difficult to identify.
A warranty request cannot be evaluated from a short description such as "the nut is broken." The supplier normally needs the order information, product identification, operating conditions, installation details, photos, videos and a description of when the problem first appeared.
What to Do Immediately After Finding a Ball Nut Problem
- Stop the machine safely.
Do not continue running the ball screw to see whether the noise, vibration or resistance disappears. Continued operation can damage the raceways, balls, return system and support bearings. - Record the symptom before changing anything.
Take a clear video showing the complete ball screw assembly, movement direction, sound and the position where the problem occurs. - Do not disassemble the ball nut without instructions.
Removing the nut from the screw shaft without a suitable transfer sleeve can cause the balls to fall out. Do not open the return tube or end cap, replace balls or adjust preload before the supplier reviews the problem. - Preserve all components.
Keep any loose balls, seals, return components, broken pieces, labels and original packaging. Do not clean away all lubricant or metal debris before photographing the condition. - Check for an immediate external cause.
Without dismantling the ball nut, inspect whether the screw is visibly bent, contaminated, dry, misaligned or damaged by impact. - Contact the original supplier.
Send the order information and technical evidence together rather than sending only a general complaint.
Information Required for a Ball Nut Warranty Evaluation
Providing complete information at the beginning helps the supplier identify whether remote troubleshooting is possible or whether the product must be returned for inspection.
| Required Information | What to Provide | Why It Is Needed |
|---|---|---|
| Order identification | Order number, invoice, purchase date and quantity | Confirms the supplied product and applicable order terms |
| Product identification | Complete ball nut or ball screw model, diameter, lead and accuracy grade | Identifies the structure, load rating and original configuration |
| Problem description | Noise, resistance, backlash, ball loss, seal damage, cracking or other symptom | Defines the failure mode that must be investigated |
| Time of occurrence | Before installation, during initial testing or after a period of operation | Helps distinguish delivery damage, installation problems and operating wear |
| Photos | Complete assembly, name or model label, damaged area, lubricant and surrounding structure | Shows physical condition and installation arrangement |
| Video | Slow manual rotation or safe low-speed movement with original sound | Shows whether the problem is continuous, periodic or position-dependent |
| Operating conditions | Load, speed, acceleration, duty cycle, stroke and installation direction | Checks whether the application is within the selected configuration |
| Installation information | Support units, alignment method, nut-housing mounting and coupling arrangement | Helps identify misalignment, forced assembly or support problems |
| Lubrication record | Lubricant type, amount, application method and relubrication interval | Checks for insufficient, incompatible or contaminated lubrication |
| Changes or repairs | Any disassembly, ball replacement, preload adjustment or machine modification | Confirms whether the original product condition has changed |
Common Causes That Must Be Distinguished
The same operating symptom can have several possible causes. For example, high running torque may come from the ball nut itself, but it can also be created by an incorrectly aligned bearing support, a distorted nut housing or contamination on the screw raceway.
| Observed Symptom | Possible Product-Related Cause | Possible Installation or Operating Cause |
|---|---|---|
| High or uneven torque | Raceway defect, incorrect internal fit or damaged return component | Misalignment, bent screw, forced nut housing, contamination or unsuitable lubricant |
| Abnormal noise | Damaged balls, return-system problem or surface defect | Insufficient lubrication, chips, excessive speed, support-bearing noise or coupling misalignment |
| Excessive backlash | Incorrect clearance, preload loss or premature internal wear | Loose mounting bolts, support-bearing clearance, coupling movement or overload wear |
| Balls have fallen out | Return component or retaining structure damage | Nut removed without a transfer sleeve or return component opened during disassembly |
| Pitting or rapid wear | Material, hardness or raceway-quality issue | Overload, impact, inadequate lubrication, contamination or unsuitable operating environment |
| Flange or nut-body damage | Material or manufacturing defect | Uneven bolt tightening, incorrect mounting face, collision or external load |
This comparison is used for initial diagnosis only. The actual cause should not be concluded from one photograph or symptom without checking the complete assembly and operating history.
How a Ball Nut Warranty Issue Is Evaluated
DLY ball screw products are generally supplied with a 12-month warranty, subject to the confirmed product, order documents and agreed terms. A report submitted during the warranty period still requires technical evaluation; it does not automatically establish that the product has a manufacturing defect.
A practical evaluation normally follows these steps:
- Order verification: Confirm the supplied model, quantity, delivery date and original technical requirements.
- Remote evidence review: Review photos, videos, drawings, operating conditions and maintenance records.
- Initial troubleshooting: Check whether the symptom may come from alignment, support bearings, lubrication, contamination, mounting or control settings.
- Return decision: If the cause cannot be confirmed remotely, determine whether the ball screw or nut assembly should be returned for inspection.
- Product inspection: Depending on the problem, inspect appearance, ball circulation, running torque, backlash, raceway condition and relevant dimensions.
- Cause assessment: Compare the inspection findings with the original product specification and the recorded application conditions.
- Resolution: Communicate the available repair, replacement, technical correction or other handling method according to the confirmed cause and order terms.
Customers should wait for return instructions before shipping. Returning only the ball nut may be insufficient when the problem could involve the matching screw shaft, support units or installation alignment.
How to Reduce Warranty Claim Delays
- Use the original order number in the email subject.
- Send original photos and videos rather than compressed screenshots.
- Show both the damaged area and the complete machine installation.
- State the problem in measurable terms where possible, such as backlash, torque, running hours or the position where resistance occurs.
- Explain whether the symptom existed before installation or developed during use.
- Do not remove balls, polish the raceway or replace internal components before receiving instructions.
- Keep the screw shaft and nut as a matched assembly when their original matching condition may affect inspection.
- Do not ship the product until the return address, scope and packaging method are confirmed.
Before installation, buyers can also perform an incoming inspection of the model, flange, seals, lubrication condition and rotational smoothness. See How to Check Ball Screw Nut Quality Before Installation for a practical inspection guide.
For a DLY ball nut or SFU ball screw issue, send the order number, complete model, photos, video, operating conditions, installation drawing and lubrication record for evaluation.
Email: dlyexport2@dlybearing.com | WhatsApp: +86 166 0578 8856
