TF COMBO BAG (Thermally Formed Combo Bag)

TF Combo Bag is a one-piece thermoformed integrated fiberglass filter and flow control bag, specially engineered for high-standard molten aluminum purification used in permanent mold casting, gravity die casting, and vertical DC billet casting.

Unlike traditional manually sewn filter bags, the TF Combo Bag adopts full hot-press integral molding technology. There are no sewing threads, stitching gaps or loose fiber residues on the whole bag body. The bag is impregnated with imported high-temperature smokeless phenolic resin and treated by high-pressure carbonization. This treatment delivers permanent shape fixation, excellent high-temperature rigidity, oxidation resistance, and ultra-low smoke emission during aluminum pouring.

1. Raw Material Composition & Grade Standard

● Base material: Premium alkali-free E-glass fiber woven fabric with low iron content

● Double-layer composite construction:

      1. Outer layer: Thick high-tensile fiberglass mesh for large slag interception and structural support

      2. Inner layer: Fine uniform mesh for deep filtration of micro inclusions

● Impregnating agent: Low-smoke flame-retardant modified phenolic resin, casting grade compliant with European standards

● Production workflow: Dipping → high-temperature drying → high-pressure thermoforming → secondary carbonization curing → final hardening

● The formulation strictly controls iron content and volatile substances. It brings no secondary contamination to molten aluminum, with no black smoke, strange odors or fiber shedding under high casting temperatures.

2. Core Physical & High-Temperature Performance Parameters

● Maximum continuous working temperature: 1000°C

● Instant temperature resistance: up to 1150°C

● High-temperature rigidity retention: maintains shape for 90–120 minutes in molten aluminum at 720–760°C

● Tensile strength (dry and hot state): ≥8.5 kg per strand, no deformation or expansion under long-term scouring of molten metal

● Filtration precision range: 5μm–50μm

● Standard mesh aperture: 1.5×1.5mm / 2.0×2.0mm / 2.5×2.5mm

● Liquid permeability: consistent flux, no localized clogging and stable flow rate of molten aluminum

● Combustion property: low smoke, non-flammable, no dripping residues

3. Structural Design Principle: Combo Multi-Function Integration

The term "Combo" stands for three core functions combined within one single product:

● Filtration: Double-layer gradient filtration removes alumina slag, oxide films, suspended particles and tiny non-metallic inclusions.

● Flow stabilization: Integrated cavity structure eliminates liquid turbulence, splashing and swirling flow of molten aluminum.

● Diversion & distribution: Optimized internal channels enable even mold filling, balance temperature differences and improve the consistency of finished castings.

The seamless monolithic structure completely solves common defects found in traditional sewn bags: thread shedding, floating fibers and slag leakage through stitching gaps.

4. Key Advantages Over Traditional Sewn Filter Bags

1. Zero inclusion-related defects:

Without sewing threads or loose fibers, threads will not break under high heat.

It fundamentally prevents thread residues from mixing into molten aluminum, which causes pinholes, slag holes and blowholes in wheel hubs and castings.

2. Sustained three-dimensional rigidity at high temperature:

Conventional soft sewn bags soften, expand, sag or deform once exposed to hot aluminum liquid, resulting in unstable flow and sudden slag leakage.

TF thermoformed bags retain their full 3D shape throughout the whole casting cycle.

3. Ultra-low smoke and eco-friendly pourin:

Formulated with low-volatility carbonized resin.

It generates almost no smoke or pungent odor during pouring and meets EU environmental standards for manufacturing workshops.

4. No preheating required for higher efficiency:

Great thermal shock resistance. It can be installed and used directly without preheating, reducing process steps and shortening casting cycle time.

Uniform flow and suppressed oxidation.

It restrains liquid turbulence and reduces secondary oxide slag formation, greatly improving casting surface finish and internal compactness.

5. Industrial Application Scenarios:

● Gravity casting of aluminum alloy automotive wheel hubs

● Casting of automotive engine blocks, cylinder heads and aluminum brackets

● Vertical DC casting of aluminum billets, round bars and flat ingots

● Low-pressure die casting and precision aluminum casting

● High-end aluminum profiles and semi-finished aerospace aluminum castings

6. Customization Capability

● Full-size customization: inch and metric dimensions to match customer launders and molds

● Custom mesh density and double-layer matching ratio

● Custom diversion nozzles, bottom holes and side hole structures

● Custom hardness and rigidity holding time

● OEM logo printing and neutral export packaging

● Reinforced high-temperature version available for long-cycle casting

7. Quality Certification & Industrial Standards

Compliant with international casting industry specifications:

✅ISO 9001 Quality Management System

✅ISO 14001 Environmental Management System

✅ISO 45001 Occupational Health and Safety Management System

✅All raw materials are tested with MSDS safety data sheets

TF COMBO BAG FAQ

1: What is a TF Combo Bag?

TF Combo Bag (Thermally Formed Combo Bag) is a one-piece thermoformed fiberglass filter bag for molten aluminum. It combines filtration, flow stabilization and diversion in one unit. Unlike sewn filter bags, it is seamless and thread-free.

2: What temperature can the TF Combo Bag withstand?

Continuous working temperature reaches 1000°C. It can withstand instantaneous peaks up to 1150°C. It maintains its rigid shape for 90–120 minutes under normal aluminum casting temperature (720–760°C).

3: What are the main differences between TF Combo Bag and traditional sewn filter bags?

The biggest difference is the one-piece hot-press forming without sewing threads. Sewn bags carry risks of loose threads, fiber shedding and bag collapse at high temperature. TF Combo Bag eliminates thread contamination, retains full shape during pouring, produces low smoke and requires no preheating.

4: Do I need to preheat the TF Combo Bag before casting?

No preheating is required. The product features excellent thermal shock resistance. Install it into the launder directly before pouring molten aluminum, which saves production time.

5: What mesh sizes are available? Can I customize the mesh?

Standard mesh: 1.5×1.5 mm, 2.0×2.0 mm, 2.5×2.5 mm. Custom mesh density, double-layer fabric matching and aperture specifications are available upon request.

6: What casting applications is the TF Combo Bag suitable for?

It is widely used for aluminum alloy wheel hubs, engine blocks, cylinder heads, aluminum billets, flat ingots and precision aluminum castings. It fits gravity casting, low-pressure casting and vertical DC semi-continuous casting.

7: Can the dimensions and structure be customized?

Yes. We can customize overall dimensions (metric or inch), diversion nozzles, bottom holes and side holes. OEM logo printing and neutral export packaging are supported. Reinforced high-temperature versions for long-cycle casting are also available.

8: What certifications do you provide?

Our products are certified with ISO9001, ISO14001, ISO45001. MSDS documents for raw materials can be supplied for customer inspection.

9: Will the bag collapse or deform during long pouring cycles?

Under normal casting temperature 720–760°C, the TF Combo Bag maintains stable 3D rigidity for 90–120 minutes. It will not sag, expand or collapse during the full casting cycle.

10: Does the TF Combo Bag generate heavy smoke when pouring aluminum?

No. It adopts low-volatility modified phenolic resin. Only minimal smoke is released during pouring, without pungent odor, complying with EU workshop environmental requirements.

11: What causes pinholes and slag holes in aluminum castings? Can TF Combo Bag help solve this?

Pinholes and slag holes often come from oxide inclusions and loose fibers/threads from sewn filter bags. TF Combo Bag is seamless and thread-free, greatly reducing inclusion defects and improving casting yield.

12: Can it directly replace existing sewn filter bags on our production line?

Yes. It can be directly installed to replace conventional sewn filter bags with no modification needed to your current launder system.