If you’ve ever worked with industrial filtration systems, you know that not all filters are created equal.
Two of the most widely used types in factories and process lines today are the String Wound Filter Cartridge and the PP Melt-Blown Filter Cartridge.
At first glance, they might look similar — both are tubular filters designed to remove impurities from liquids.
But in real use, they behave quite differently depending on the liquid type, pressure, and filtration precision required.
1. What Exactly Is a String Wound Filter Cartridge?
A String Wound Filter Cartridge is produced by tightly winding a fiber yarn — usually cotton, polypropylene, or glass fiber — around a central core.
The result is a dense, layered structure that traps larger particles near the surface and finer ones deeper inside.
This type of filter is well-known for its strong mechanical strength and long lifespan, especially when used in applications involving high viscosity liquids or high pressure.
Typical Features:
- Excellent dirt-holding capacity and long service cycle
- Handles thicker or more contaminated liquids effectively
- Can be made from cotton or polypropylene yarns
- Works well under higher pressure without collapsing
- Widely used in plating, chemical, and water filtration lines
From our own experience with PCB process systems, the string wound type performs better where durability matters more than micron precision.
2. What About the PP Melt-Blown Filter Cartridge?
The PP Melt-Blown Filter is made from 100% polypropylene using a thermal melting and high-speed blowing process.
This creates a continuous fiber structure with uniform pore sizes and no adhesives — making it both clean and highly efficient.
Because of its smooth and compact texture, this type is more often used where fine filtration and purity are critical.
Typical Features:
- Consistent filtration accuracy (from 1μm to 100μm)
- Made from food-grade polypropylene
- Excellent chemical resistance and cleanliness
- Ideal for RO pre-filtration and electronic manufacturing
- Lightweight, cost-effective, and easy to replace
In fact, many PCB factories choose melt-blown filters for rinsing and final cleaning tanks, where precision is key.
3. A Quick Comparison
| Category | String Wound Filter | PP Melt-Blown Filter |
| Material | Cotton / PP yarn | 100% Polypropylene |
| Structure | Wound layers (gradient density) | Melt-blown fiber structure |
| Precision | 5–100 μm | 1–100 μm |
| Strength | Excellent under high pressure | Moderate |
| Best Use | High-viscosity or dirty liquids | High-purity or clean liquids |
| Applications | Chemical, plating, water | PCB, RO, electronics |
| Cost | Slightly higher | Lower, economical |
4. How to Choose Between Them
From a practical point of view, the choice depends on your process type:
✅ Go with String Wound Filters if you:
- Handle thicker liquids or plating solutions
- Need higher mechanical strength
- Want longer intervals between filter changes
✅ Go with PP Melt-Blown Filters if you:
- Need high-precision filtration (1–10 μm range)
- Handle ultrapure water or electronic-grade liquids
- Want a cost-effective, clean option for daily use
In some cases, factories even use both types — string wound filters for pre-filtration and melt-blown ones for final polishing.
5. Our Perspective
At Shenzhen Qixingyuan Machinery Parts Co., Ltd., we’ve supplied both wound and melt-blown filter cartridges for years to PCB and chemical manufacturers worldwide.
Our team has tested these filters under different process conditions, and we’ve seen how choosing the right one can significantly extend equipment life and reduce maintenance downtime.
We provide:
- Consistent quality from our own production facility
- Competitive pricing with short lead times
- Custom specifications for different process lines
If you’d like to test which filter suits your system best, we’d be happy to send samples or discuss your current setup.
📞 Contact us today to get technical support or a customized filtration solution.
