Injection molding filter cartridge

Filter Cartridge Molding / Multi-stack Disc Water Filter Element Injection Molding

Processing Capabilities for PP Filter Cartridge

Item	Detailed Capabilities
Material (Housing/Cage)	PP (Polypropylene), Nylon (PA6/PA66), ABS, or custom engineering plastics
Material (Filter Media)	PP
Disc Diameter	5–500 mm (custom sizes available)
Cartridge Outer Diameter	50–300 mm (custom sizes available)
Cartridge Length	5" to 40" (127–1016 mm), custom lengths available
Shapes	Cylindrical, pleated, multi-layered, conical, or fully custom designs
Filtration Accuracy	1–1000 μm (nominal or absolute rating)
Structure	Single layer, multiple layers, pleated, or composite structures with inner core and outer cage support
Frame Style	Insert molding, ultrasonic welding, heat staking, or snap-fit assembly
Connection Types	Threaded (BSP, NPT, Metric), bayonet, push-fit, flange, or custom connections
Port Size	1/4" to 4" (DN8–DN100), custom sizes available
Pressure Rating	0.6–1.6 MPa (6–16 bar), depending on material and design
Temperature Range	-40°C to 120°C (depending on housing material)
Sealing Method	O-ring, gasket, end-cap over-molding, or integrated seal
Assembly	Complete PP filter cartridge assembly including outer cage, inner core, filter media, end caps, and seals
Surface Finish	Smooth, textured, or custom finishes available
Color	Black, white, grey, blue, or custom colors matched to customer requirements
Processing Tolerance	Diameter tolerance ±0.1mm, Length tolerance ±0.5mm
Certifications	ISO9001, ROHS, CE, food-grade options available
Applications	Water treatment, RO pre-filtration, chemical processing, pharmaceutical, food & beverage, HVAC, marine, and industrial fluid filtration

Manufacturing Process of PP Filter Cartridge

1. Raw Material Preparation

Select high-quality polypropylene (PP) pellets based on application requirements (filtration accuracy, chemical compatibility, temperature resistance). The raw material is dried and pre-conditioned to remove moisture, ensuring optimal molding performance.

2. Injection Molding of Outer Cage & Inner Core

Precision injection molding produces the outer protective cage and inner support core. The mold uses a balanced runner system to ensure uniform filling and minimal warpage. Process parameters (melt temperature, injection pressure, cooling time) are strictly controlled to achieve dimensional accuracy and structural integrity. The cage ribs and slots are molded to precise tolerances to ensure proper media support and fluid flow.

3. End Cap Molding

The top and bottom end caps are injection molded with integrated sealing features (O-ring grooves, threaded connections, or bayonet fittings). End caps are designed to screw into the filter housing and provide a leak-proof seal with the housing.

4. Seal & Gasket Installation

O-rings, gaskets, or integrated over-molded seals are installed at all critical connection points (end caps, threaded ports) to ensure a leak-proof assembly. Seal materials are selected for compatibility with the intended fluid and operating temperature.

5. Final Assembly

Assemble the complete PP filter cartridge by inserting the media-core assembly into the outer cage, securing the end caps, and tightening all connections. Each unit is checked for proper fit, alignment, and dimensional accuracy.

6. Quality Control & Testing

Every batch undergoes rigorous quality inspection, including:

• Dimensional verification (outer diameter, length, port size)
• Pressure testing (leak-proof performance at rated pressure)
• Filtration accuracy testing (micron rating verification)
• Bonding strength testing (end cap to media)
• Visual inspection for defects (flash, warpage, discoloration)

Manufacturing Challenges & Countermeasures for PP Filter Cartridges

1. Cage Deformation & Warpage

Item	Description
Challenge	The outer cage and inner core (thin ribs and slots) tend to warp or deform during cooling, affecting dimensional accuracy and fit with end caps.
Root Cause	Uneven wall thickness between ribs and rings; inconsistent cooling rates; insufficient packing pressure; high injection speed causing turbulent flow.
Countermeasure	Optimize mold design with balanced cooling channels; use CAE simulation to predict and correct shrinkage; increase packing pressure and time; adjust gate location to ensure uniform flow; use gradual cooling profile.

2. End Cap Bonding Failure

Item	Description
Challenge	The end caps may detach from the filter media, causing bypass leakage and filtration failure.
Root Cause	Contaminated media surface; insufficient melt temperature; low bonding pressure; incompatible materials; smooth media edge with no mechanical anchoring.
Countermeasure	Pre-clean media with ultrasonic or plasma treatment; increase melt temperature and bonding pressure; design mechanical anchors (grooves, ribs, or perforations); use compatible materials for end caps and media.

3. Internal Stress & Cracking

Item	Description
Challenge	Molded parts (cage, core, end caps) may develop internal stress, leading to cracks or premature failure under pressure.
Root Cause	Rapid cooling; excessive packing pressure; sharp corners or abrupt wall thickness transitions; insufficient material drying.
Countermeasure	Optimize cooling profile (gradual cooling); reduce packing pressure; design generous fillets and smooth transitions; pre-dry material thoroughly; post-mold annealing to relieve stress.

4. Seal Installation & Leakage

Item	Description
Challenge	Improper seal installation or damaged O-rings can cause leakage at end caps or threaded connections.
Root Cause	Dimensional deviation of mating parts; damaged O-rings; insufficient torque during assembly; incompatible seal material.
Countermeasure	Maintain tight dimensional tolerances; inspect O-rings before installation; use torque-controlled assembly tools; select seal material compatible with the fluid and temperature.

Our Workflow

A transparent, step-by-step process from design to delivery — tailored for PP filter cartridges.

Stage 1: R&D Support

We support customer R&D for PP filter cartridge applications. Create the files or improve the design if needed (UG, SolidWorks, ProE, AutoCAD, etc.). We help optimize cage geometry, core structure, end cap design, port size, thread type, and sealing design for your specific fluid filtration requirements.

Stage 2: Mold Process

Mold design (DFM report) → check/approve → approved → make mold → produce sample → sample confirmed → check final mold quality ready to export.
Includes outer cage mold, inner core mold, end cap mold, thread inserts design.

Stage 3: Sample Modification

If the first sample does not meet the customer's requirements (e.g., pressure rating, thread fit, sealing performance, filtration accuracy, or pleat integrity), we can modify the mold to meet them.

Stage 4: Sample Delivery

Produce the customer's requested quantity of PP filter cartridge samples, with free shipping.

Stage 5: Final Delivery

Deliver goods by sea or air; we can accommodate special requirements based on customer demands.
Packaging options are available to protect cartridges from damage, deformation, and contamination during transport.

Why Choose Yixing Technology?

Partner with a trusted leader in precision PP filter cartridge manufacturing.

20+ Years Experience
We have successfully produced more than 1500 new injection molds and parts since 2006.
Extensive experience in molding outer cages, inner cores, end caps, threaded connections, and assembling PP melt-blown, pleated, and mesh filter cartridges.

ISO9001 Certificated
Strict quality control system, providing ROHS/CE certification for your peace of mind.
We inspect each PP filter cartridge batch for dimensional accuracy, thread quality, pressure resistance, sealing performance, bonding strength, and filtration efficiency.

One Stop Service
We provide more value-added operations to simplify your supply chain from design to delivery.
From cage and core injection molding and media die-cutting to pleating, end cap bonding, assembly, pressure testing, and global shipping — all under one roof.