When you receive new linear guide rails, it is common to see some oil film on the surface, traces from the packaging or even minor scratches on non-critical areas. Many users worry that this means the product is “used" or “defective". From an engineering perspective, however, these phenomena usually come from normal rust-prevention and handling processes, rather than quality problems.

Linear guides are high-precision steel components. Once the rail and raceway surfaces are exposed to air and moisture without protection, they may rust or oxidize, which will shorten service life and affect running accuracy.

To avoid this, a uniform anti-rust oil film is applied before shipment. This protective layer helps the guides withstand long-distance sea or air transportation, humidity changes and minor vibration or friction during handling.

If a linear guide arrives completely dry and oil-free, that is actually a risk signal: it may have been stored or handled without sufficient protection and could be more likely to rust.

The small scratches or rub marks you may notice are usually located on the side faces of the rail, the top chamfer or other non-sliding surfaces. They are typically caused by:

• Light contact with inner packaging materials during transportation;
• Slight rubbing between non-critical surfaces of rails in batch packing.

The real functional areas of a linear guide – the running surface of the rail and the raceways – are specially protected during production and packing. These key surfaces are kept free from damage to ensure precision and smooth movement.

Linear guides are industrial components rather than consumer gift items. The primary design goal of the packaging is to protect precision surfaces and dimensions, not to keep the outer carton flawless. As a result, it is normal to see:

• Compression marks on the outer box after stacking and transport;
• Tape marks, label marks or slight deformation of the carton;
• Imprints from foam, separators or shrink film on the product surface.

As long as the inner protection and oil film are intact, these marks do not affect the performance or service life of the linear guide rails.

If you feel there is too much oil on the outside and it affects handling, you may:

• Use a clean, soft, non-woven cloth;
• Gently wipe the external surfaces of the rail and block;
• Optionally use a neutral cleaner on non-functional surfaces before installation.

This will remove excess oil without harming the basic rust-preventive film. After cleaning, you can re-apply grease or oil according to your own lubrication standard and operating conditions.

If the guides will be directly installed into finished machines for sale and visible to your end users, you may have higher cosmetic requirements. In this case, please inform us in advance, for example:

• “Clean appearance required",
• “Less oil on visible surfaces",
• “Extra cleaning before packing".

Based on your request, we can add extra steps such as manual surface cleaning or additional dust protection film on visible areas, while still keeping adequate rust prevention for long-distance shipment.

The following conditions are not normal and should be treated as damaged goods:

• Deep dents, obvious impact marks or broken edges on the rail;
• Visible damage on the running surface or raceway area;
• Deformation on mounting surfaces or mounting holes that affects alignment or installation.

If you encounter any of the above, please:

• Take clear photos of the damaged area and the product label or marking;
• Record the arrival date and packaging condition;
• Send the information to your sales contact or customer service team.

After confirmation, a replacement or other proper solution can be arranged to avoid impact on your production schedule.

For linear guides, what really matters is not whether the surface looks like a perfectly polished gadget, but whether:

• The movement is smooth and free from sticking or abnormal noise;
• The rail and raceway surfaces are intact and well protected;
• The mounting dimensions and precision are within tolerance for your application.

With proper rust-prevention oil and standard industrial packaging, a small amount of oil film or minor marks on non-functional surfaces is normal and does not indicate poor quality. If you have any questions after receiving the goods, please feel free to contact us. We are always willing to help you check and solve any issues so that you can use every linear guide with confidence.