In the production of medical devices (e.g., catheters, syringes, implantable housings, connectors), the stability and surface cleanliness of injection‐molding tools are extremely critical. In traditional processes, to prevent the molten polymers (such as PC, PEEK, TPU, PMMA) from sticking to the mold during high-temperature, high‐pressure injection molding, mold release agents or surface lubricants are typically needed.

As part of production, it is usually required to pass the ISO 10993 series of biocompatibility testing. If the release agents (commonly silicone oils, waxes, or fluorocarbon compounds) remain on the product surface, three major risks may occur:

• Impact on cytotoxicity (cell toxicity) test results;
• Interference with sterilization procedures (such as EtO or γ-irradiation);
• Abnormal drug adsorption or release from devices in contact with drugs (especially hazardous).

Therefore, in medical manufacturing, release agents are considered as a potential contaminant, which may cause regulatory/verificative failures or post-processing issues. Relying on release agents in production will affect cleanliness control, GMP/QMS traceability, and the final product’s biocompatibility.

However, release agents tend to volatilize or oxidize under high temperature, and may contaminate the surface of medical parts — affecting subsequent sterilization, packaging, or even the safety of drug contact surfaces.
Power-Micro International has introduced a microparticle anti-adhesion surface modification technology, combined with IF-WS₂ (inorganic fullerene-like tungsten disulfide) nano-coating, to create a molding tool surface that does not require mold release agents (release-agent-free). This technology maintains extremely high cleanliness while effectively preventing high‐temperature resin adhesion, extending mold life and reducing production/maintenance costs.

◆ Practical Risks: Process Control Under GMP/QMS

Medical devices must comply with ISO 13485 and 21 CFR Part 820 (FDA QSR), requiring all materials and auxiliaries in contact with the product to be traceable, controlled, and non-impacting to product safety. Typical problems with release agents include:

• They cannot be fully removed and easily remain on tool or product surfaces;

• Aerosol or silicone-based release agents are harder to control in terms of coating thickness and uniformity;

• They increase complexity and cost for clean‐room and pre‐sterilization processing.

• Thus, from the design stage, mold-release-free processes are recommended to reduce downstream risks and verification burden.

◆ If You Can’t Use Release Agents, What Can Production Engineers Do?

Engineers often ask: “If no release agent can be used, how should the injection mold be designed and processed?” We recommend adopting (or combining) the following strategies:

1. Increase draft angle: Within acceptable product tolerances, increase the demoulding angle to reduce mechanical stick-in and adhesion contact area.
2. Control injection parameters (mold temperature, melt temperature, hold pressure): Strictly adjust to avoid excessive shrinking causing jamming or surface adhesion, and optimize with temperature curves and fill-time control.
3. Use self-lubricating resins: Use specialty resins containing PTFE or siloxane copolymers (supplied by e.g., Asahi Kasei in Japan) to reduce melt-to-mold interface adhesion tendency.
4. Optimize venting and ejection structure: For example, improve gas release valve layout, ejector-pin configuration and vent groove design to avoid gas entrapment in cavities causing burn marks or local adhesion.
5. Mold maintenance and cleaning procedures: Regular polishing, ultrasonic cleaning of cavities; prohibit use of oil-based or high-residue detergents; use no‐residue cleaners or higher-grade cleaning process when necessary.
6. Clean-room grade control: Production environment is recommended Class 10000 (ISO 7) or better, with strict access and gowning procedures to prevent contamination.

◆ Technical Principle – Microparticle Surface Modification & IF-WS₂ Anti-Adhesion Coating

• Micro-Particle Surface Modification

Using high-pressure spraying of nano/alloy micro‐particles combined with high‐pressure gas jets or mechanical impact on the mold surface, a nano‐plastic deformation layer is formed. This layer generates high residual compressive stress, increases mold surface hardness and crack resistance, while reducing surface energy — thereby lowering polymer melt wettability. This means that when the resin contacts the mold, its wettability is reduced and adhesion is less likely.

• Anti‐Adhesion IF-WS₂ Coating

IF-WS₂ (Inorganic Fullerene-like Tungsten Disulfide) is a spherical nano-structured material, featuring a low friction coefficient (µ ≈ 0.03–0.05) and excellent thermal stability (> 600 °C). Through electrochemical exfoliation and conformal deposition, a dense solid-lubricant film is formed on the mold surface, offering self-lubrication and withstanding high-pressure, high-temperature cycles of injection molding. It has a very low friction coefficient (approx µ = 0.03–0.06), high temperature stability (resistant to >300–600 °C depending on system), low surface energy, suppressing chemical bonding or mechanical adhesion between metal and resin. This coating contains no organic silicone or fluorinated components, and fully conforms to ISO 10993 / USP Class VI biocompatibility standards — applicable for molds producing medical implants, catheter connectors, single-use disposables, etc.

◆Implants & Invasive Devices

Applicable examples: silicone breast-implant shells, artificial joint housings, pacemaker housings, etc — these products have the highest biocompatibility demands and cannot accept any release-agent residues. Adopting this technology enables release-agent-free production, reduces biocompatibility risk and simplifies validations.

◆Ophthalmic & Oral Contact Devices

Applicable examples: contact-lens molds, orthokeratology lens carriers, oral devices. Surface cleanliness and optical quality are critical; the IF-WS₂ coating and microparticle substrate are ultra-thin and smooth, and do not affect the optical forming performance of transparent materials.

◆Drug-Contact Devices & Disposables

Applicable examples: syringes, injection devices, drug-delivery devices. Avoiding release agents reduces drug adsorption risk and ensures dosage and efficacy consistency. Using microparticles + IF-WS₂ can reduce surface residue to extremely low levels.

◆Drug-Contact Devices & Disposables

Applicable examples: syringes, injection devices, drug-delivery devices. Avoiding release agents reduces drug adsorption risk and ensures dosage and efficacy consistency. Using microparticles + IF-WS₂ can reduce surface residue to extremely low levels.

◆Performance Data

• Residue amount: Polymer residue on cavity surfaces reduced by approximately 90–95%.
• Surface roughness: After treatment still maintains the smoothing level required for molding (coating thickness typically 200–400 nm, not affecting tolerance).
• Yield/Maintenance: Defect rate significantly reduced; mold cleaning frequency reduced from weekly to monthly; mold life increased ~2–3× (depending on material and application).

◆Technical Advantages & Limitations

Applied in automotive, aerospace, and 3C product casings, combining light weight with rigidity.

Item	Technical Advantages	Possible Limitations
Anti-adhesion	Release-agent-free, achieving release-free production	Longer surface-treatment time, stricter pre-treatment
Biocompatibility	Reduced contamination risk, beneficial for ISO10993 validation	Requires testing/verification of biocompatibility materials
Process stability	Reduces downtime, increases automation feasibility	Higher initial equipment investment / process calibration cost
Compatibility	Can be used in composite with nitriding, PVD etc	Subject to mold size (e.g., ≤1000×1000 mm) or broadcast/coverage limitations

 Q&A

Q1：Will the IF-WS₂ coating change mold tolerance ?

No. The coating thickness is typically 200–400 nm, so the effect on cavity tolerance is negligible.

Q2：Will this technology affect optical properties of transparent materials (e.g., PC/PMMA)？

No. The treated surface still maintains optical-grade forming characteristics.

Q3：Does the material comply with ISO 10993 / USP Class VI？

The coating can use formulations that conform to ISO 10993 / USP Class VI, but third-party test reports are required for verification.

Q4：Can it be combined with existing PVD or nitriding layers？

Yes. Microparticle modification + IF-WS₂ can serve as underlayer or surface overlay, forming composite protection structures.

Q5：What is the expected lifespan and maintenance interval？

Most case studies show mold life extended 2–3×, and cleaning/maintenance intervals significantly lengthened (e.g., from weekly to monthly).

Q6：Are there constraints on treated area or size？

Due to equipment and process limitations, the maximum treatment area may be limited (commonly ≤1000×1000 mm); large molds may need zonal treatment or outsourcing.

Q7：What is the pay-back period of implementation cost？

Depending on production volume and downtime cost difference, the investment can typically be recouped in 12-36 months (needs project-specific calculation).

• Compared to release agents: Release agents are simple but leave residues and contaminate verification process; microparticle + IF-WS₂ offer long-term stable, residue-free solution.
• Compared to PVD / DLC / Nitriding: PVD/DLC offer hardness, nitriding improves wear‐resistance, but may be less effective for anti-adhesion or lubrication than IF-WS₂; this technology can serve as reinforcement or alternative depending on application.

This technology, with microparticle surface modification + IF-WS₂ anti-adhesion coating as the core, enables release-agent-free, low-contamination and highly stable production processes for medical injection molds. It improves yield, extends mold life, and reduces verification and sterilization risk.
If you would like to evaluate the feasibility of retro-fitting your existing molds, or request a technical report and third-party biocompatibility test data, please contact Power-Micro International for technical support and application evaluation.

Power Micro International Company offers comprehensive surface-engineering and anti-adhesion solutions to eliminate soldering/erosion defects and enhance productivity.

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