PC-Covestro Makrolon 2805
PC-Covestro Makrolon 2805 is a medium-viscosity, amorphous polycarbonate resin developed by Covestro, equipped with an internal mold release agent for efficient demolding. Boasting a melt volume-flow rate (MVR) of 9.0 cm³/10 min (at 300°C/1.2kg) and extreme mechanical toughness (notched Izod of 85 kJ/m²), this grade is optimized for high-impact structural panels, safety shields, and industrial enclosures requiring high stress-crack resistance. Jucheng Precision, under IATF 16949 and ISO 9001 quality frameworks, specializes in molding Makrolon 2805 to deliver zero-defect parts. Backed by 5-axis CNC-machined S136 tool cavities and 35+ advanced presses, we control thermal stresses and eliminate weld lines, verified by Zeiss CMM inspection.
Makrolon 2805 Mechanical & High-Impact Profile
Makrolon® 2805 is a medium-viscosity, amorphous general purpose polycarbonate resin engineered by Covestro to deliver extreme mechanical toughness, low-temperature ductility, and high creep modulus:
| Mechanical Attribute | Makrolon 2805 Nominal Value | Structural Design Advantage |
|---|---|---|
| Impact Performance | Notched Izod Impact 85 kJ/m² | Features superior rubber-like physical toughness and impact energy absorption compared to lower-viscosity grades, preventing cracks under heavy impacts. |
| Stiffness Modulus | Flexural Strength 97 MPa / Modulus 2400 MPa | Ensures a highly rigid, unbending structure, making it ideal for large-span protective industrial screens and thick-walled panels. |
| Creep Resistance | Tensile Creep Modulus (1000h) 1900 MPa | Demonstrates exceptional resistibility to dimensional elongation and structural sagging under continuous mechanical load. |
Structural Application & Molding Process Compatibility for Makrolon 2805
With intermediate melt viscosity, Makrolon 2805 delivers high melt strength to support robust, load-bearing parts:
| Molding Process | Molding Compatibility & Operational Details |
|---|---|
| Industrial Safety Shields | Excellent. Fully optimized for high-transparency machine safety guards, protective visors, motorcycle windshields, and bulletproof barriers. |
| High-Impact Enclosure Molding | Excellent. Ideal for heavy-duty power tool casings, industrial connector bodies, marine junction boxes, and safety helmet shells. |
| Insert & Valve-Gated Molding | Excellent. Highly compatible with hot-runner valve gates to optimize structural weld lines, preventing stress cracking near encapsulated metal bushings. |
PC-Covestro Makrolon 2805 Tooling & Flow Mark Mitigation Guide
Molding a medium-viscosity resin like Makrolon 2805 requires careful runner design to prevent flow marks, alongside rigorous desiccant drying to protect mechanical strength:
- Optimizing High Melt Viscosity (Runner Design): Because 2805 has a lower melt flow (MVR 9.0) than high-flow grades, cold flow marks and “blush” can easily occur near gates. Jucheng’s tooling division uses 5-axis CNC machines to cut generous, rounded runners and wide valve gates to ensure smooth, unhindered material delivery.
- Desiccant Drying & Splay Prevention: Wet polycarbonate is highly susceptible to hydrolytic polymer chain fracture, destroying impact strength and causing splay or silver streaks. We dry raw resin in desiccant hopper dryers at 120°C (248°F) for 3–4 hours, keeping moisture strictly below 0.02%.
- Melt and Mold Temperature Control: Processing barrel temperatures are maintained between 280°C and 320°C (536°F to 608°F). Mold temperatures are kept at 80°C to 110°C (176°F to 230°F) to ensure maximum gloss and reduce residual internal molding stresses.
- Isotropic Low Shrinkage: Makrolon 2805 exhibits low and highly uniform shrinkage (0.6% to 0.8%). We machine balanced, conformal cooling circuits directly into core blocks to speed up heat dissipation, further reducing cycle times and preventing thermal warpage.
Key Application Fields for PC-Covestro Makrolon 2805
- Industrial & Mechanical Safety: Large transparent machine safety guards, high-impact factory partition screens, protective helmet shells, and optical visors.
- Automotive & Heavy Equipment: Tractor cabin window glass, motorcycle windshields, automotive ambient light pipes, and heavy-duty external structural panels.
- Electrical Infrastructure: Heavy-duty high-voltage circuit breaker housings, outdoor electrical meter housings, dynamic switch boxes, and LED panel housings.
Properties
| Density | 1.2 g/cm³ |
| Melt Volume-Flow Rate (MVR) (300°C/1.2kg) | 9 cm³/10min |
| Tensile Modulus | 2,400 MPa |
| Yield Stress | 66 MPa |
| Yield Strain | 6.2 % |
| Nominal Strain at Break | >50 % |
| Strain at Break | 115 - 130 % |
| Flexural Modulus | 2,400 MPa |
| Flexural Strength | 97 MPa |
| Izod Notched Impact Strength (23°C, 3.2mm) | 85 |
| Charpy Notched Impact Strength (23°C, 3mm) | 75 kJ/m² |
| Tensile Creep Modulus (1000h) | 1,900 MPa |
| Glass Transition Temperature (Tg) | 145 °C |
| Vicat Softening Point (50N, 50°C/hr) | 144 °C |
| Heat Deflection Temperature (HDT @ 0.45 MPa) | 137 °C |
| Heat Deflection Temperature (HDT @ 1.80 MPa) | 125 °C |
| Linear Mold Shrinkage | 0.60 - 0.80 % |
| Flammability Rating (0.8mm) | UL 94 V-2 Class |
| Maximum Part Size | 1000 x 800 mm |
| Minimum Part Size | 1 x 1 mm |