PS-Sabic HIPS 638
PS-Sabic HIPS 638 is a high-impact polystyrene (HIPS) grade manufactured by SABIC, revered for its outstanding structural toughness, excellent stiffness, and controlled melt flow (MFI 8.0 g/10 min). Polymerized with rubber-modified polybutadiene domains dispersed inside a rigid polystyrene matrix, this opaque resin is the global standard for heavy-duty appliance parts, structural toys, and electronic enclosures. At Jucheng Precision, an ISO 9001 and IATF 16949 certified manufacturer, we specialize in molding HIPS 638 without surface defects. Utilizing our 25+ in-house 5-axis CNC tooling, we optimize gate sizes and packer profiles to prevent sink marks on heavy structural ribs, delivering pristine components verified by Zeiss CMM inspection.
SABIC HIPS 638 Structural Impact & Toughness Profile
SABIC® HIPS 638 is an opaque, rubber-modified high-impact polystyrene designed to deliver balanced tensile strength, easy flow, and exceptional mechanical stiffness:
| Mechanical Attribute | SABIC HIPS 638 Specs | Engineering Advantage for Molded Parts |
|---|---|---|
| Rubber Toughening | Elastomer-Modified Phase Matrix | Incorporates chemically bonded polybutadiene rubber domains, absorbing mechanical impact and preventing brittle stress fractures in structural enclosures. |
| Structural Rigidity | Tensile Modulus 2150 MPa | Maintains robust load-bearing stiffness, preventing dynamic bending or deformation in heavy-duty appliance components. |
| Flow Performance | MFR 8.0 g/10 min (200°C x 5kg) | Ensures a highly uniform melt flow under moderate shear, facilitating fast cycles in multi-cavity hot runner systems. |
Process Compatibility and Mold Setup for SABIC 638
SABIC HIPS 638 processes consistently across various high-volume injection molding configurations:
| Molding Process | Process Suitability & Operational Details |
|---|---|
| Structural Housing Molding | Excellent. Fully optimized for structural home appliance back covers, electronic enclosures, cosmetic displays, and printer trays. |
| Toy & Furniture Molding | Excellent. Supports molding of thick-walled structural toys, snap-fit components, and rigid furniture brackets requiring high durability. |
| Thin-Wall Packaging | Good. Allows high-pressure injection into thin-walled industrial storage trays and dynamic product containers with reduced cycle times. |
PS-Sabic HIPS 638 Tooling & Sink Mark Mitigation Guide
Molding an amorphous impact-modified grade like HIPS 638 requires careful gate sizing and pressure profiling to prevent cosmetic sink marks and gate blush:
- Mitigating Rib and Boss Sink Marks: HIPS has a low mold shrinkage rate (0.4% to 0.7%), but thick structural ribs can still pull material away during cooling, creating visible sink marks. Jucheng’s tooling division uses Moldflow software to optimize gate placement and designs rib thicknesses to be 50% to 60% of the adjacent wall.
- Tool Steel Selection & Finish: To achieve a pristine satin matte or glossy finish, we construct mold cavities from premium S136 stainless steel hardened to 48–52 HRC. This keeps parting lines razor-sharp and prevents rapid gate erosion.
- Scientific Injection Profiling: Processing melt temperatures are maintained between 190°C and 240°C (374°F to 464°F). Mold temperatures are kept at 35°C to 55°C (95°F–131°F). Slower injection speeds and progressive pack pressures are applied to avoid shear stress near gates.
- Ejection and Draft Optimization: Because HIPS 638 is highly rigid, deep structural ribs require polished draft angles (minimum 1.5°). We utilize broad ejector pins or stripper bars to prevent part stress and ejection drag marks.
Key Application Fields for PS-Sabic HIPS 638
- Home Appliances: Refrigerator interior components, dynamic door panels, washing machine control trims, air conditioner covers, and vacuum cleaner shells.
- Toys & Children’s Goods: Rigid building block components, durable toy vehicle chassis, play set structures, and children’s study table accessories.
- Industrial & Electronic Casings: Desktop printer trays, computer monitor back housings, industrial equipment control bezels, and secondary storage bins.
Properties
| Density | 1.04 g/cm³ |
| Melt Mass-Flow Rate (MFR) (200°C/5.0kg) | 8.0 g/10 min |
| Tensile Strength at Yield | 22.0 MPa |
| Tensile Elongation at Break | 45 % |
| Tensile Modulus | 2,150 MPa |
| Flexural Strength | 41.0 MPa |
| Flexural Modulus | 2,150 MPa |
| Izod Impact Strength (Notched, 23°C) | 140 J/m |
| Rockwell Hardness (L-Scale) | 60 - |
| Vicat Softening Point | 95.0 °C |
| Heat Deflection Temperature (HDT @ 455 kPa) | 93.0 °C |
| Linear Mold Shrinkage | 0.40 - 0.70 % |
| Flammability Rating | UL 94 HB - |
| Maximum Part Size | 1000 x 800 mm |
| Minimum Part Size | 1 x 1 mm |