Application fields:
Paper and printing machine rolls, steel mill rolls and rolls journals, pump and motor shafts, gearbox shafts, hydraulic piston rods, and sealing surfaces of rotating equipment.
Technical principles and processes:
The part is degreased, masked and grit blasted, then pre-machined where the wear is deep. Coating is applied by atmospheric plasma spray (APS) with powder selected for the duty, alternatively HVOF for carbide layers. The part is finish ground and polished on a cylindrical grinder, with roundness, hardness and coating thickness recorded.
Coating performance:
- Restores dimension from a few hundredths up to several millimetres
- Coating options: alumina and chrome oxide ceramic, WC carbide, Ni-based alloys
- Finish ground and polished, Ra 0.4 or better where required
- Micro-hardness from 700 HV (ceramic) to 1400 HV (carbide)
- Dimensional and hardness report supplied with every part
辊类与轴类等离子喷涂修复：针对磨损、拉伤、腐蚀导致的尺寸超差，用等离子喷涂恢复尺寸并附加陶瓷或碳化钨耐磨层，磨削至图纸公差。
Restoration capability
| Item | Capability |
|---|---|
| Diameter range | 20 mm to 1,500 mm |
| Face length | Up to 6,000 mm |
| Build-up per setup | 0.10-1.00 mm (plasma), up to 3 mm with arc spray base |
| Coating options | NiAl bond + Al2O3, Cr2O3, WC-Co, stainless |
| Finish | Cylindrical grinding to Ra 0.1-0.8, runout under 0.02 mm |
| Balancing | ISO 1940 G2.5 on request |
Restoration sequence
Incoming inspection and hardness check → strip any previous coating or chrome → straighten if required → rough grind to clean, true surface → degrease and grit blast → bond coat → spray build-up → slow cool → cylindrical grind → polish → runout and thickness report.
Where restoration beats replacement
A 4 m paper machine roll or a forged mill roll is a long-lead, high-value component. Restoring 0.3 mm of worn diameter costs a small fraction of replacement and typically takes one to two weeks instead of three months. The limit is the substrate: if the roll is cracked, corroded through the coating zone, or below minimum wall thickness, replacement is the only responsible answer - and we will say so rather than coat a part that will fail.
Frequently asked questions
How much diameter can be restored?
Up to 1 mm per side with plasma ceramic on a sound substrate, more if an arc sprayed build-up layer is used underneath. Beyond that the economics usually favour a new roll body.
Will the roll keep its original hardness?
The substrate hardness is unchanged - the coating is applied cold. The surface hardness becomes that of the coating, typically 900-1,300 HV depending on material.
Can you match the original surface finish?
Yes. We measure the incoming Ra and reproduce it, from Ra 0.1 for seal surfaces to Ra 0.8 for web contact.
Further reading: 5 signs rolls need recoating.
