KRAIBURG TPE Enhances Injection Molding Efficiency

Imagine your brilliantly designed product being compromised by injection molding defects—this represents a significant manufacturing setback. Injection molding serves as the critical process for plastic part production, where material selection and precise process parameters determine success. This comprehensive guide explores the application of KRAIBURG TPE materials in injection molding to achieve optimal results.

KRAIBURG TPE (thermoplastic elastomer) materials have gained prominence for their exceptional performance and versatile applications. Compared to conventional thermoplastics, TPE combines rubber-like elasticity with plastic processability, making it ideal for diverse applications. These materials typically come in free-flowing granule form, facilitating processing on standard injection molding machines.

Standard thermoplastic injection molding machines generally suffice for processing KRAIBURG TPE materials. However, optimal performance requires specific screw design considerations. An ideal three-zone screw should feature at least a 2:1 compression ratio and minimum 20:1 length-to-diameter (L/D) ratio. This configuration ensures thorough material mixing and homogeneity during melting and plasticization, enhancing final product quality.

Both open and closed nozzles can process KRAIBURG TPE materials, though closed nozzles typically offer superior process control. Closed nozzles effectively prevent material drooling and stringing, improving production efficiency and product quality. Additionally, they enable precise control over injection volume and speed, further optimizing the molding process.

THERMOLAST® K series materials generally tolerate extended residence times, providing processing flexibility. However, practical operations should minimize barrel residence time, particularly in hot runner systems. Excessive residence time may cause material degradation and performance deterioration. Operators should carefully balance material characteristics with process requirements.

Hot runner systems play a crucial role in maintaining uniform melt temperature and pressure to the cavity, enhancing product quality and production efficiency. Poorly designed systems may cause material stagnation and degradation. System volume should not exceed 1-3 times the shot volume—excessive volume increases degradation risk through prolonged residence time.

These parameters critically influence molding quality. Appropriate settings ensure complete cavity filling with excellent surface finish and dimensional accuracy. Optimal parameters vary according to part design, gate location, and material structural viscosity. Higher structural viscosity typically requires faster injection speeds to achieve proper filling, particularly for thin-walled components.

A progressive injection approach optimizes filling. Initial machine startup should use medium speed without packing pressure. Starting from half the calculated shot volume, operators can incrementally increase by 10% until complete cavity filling occurs. Injection profiling further enhances filling by adjusting speed and pressure according to part geometry requirements.

The packing phase compensates for material shrinkage during cooling, preventing sink marks and warpage. Proper packing time and pressure settings prove critical—excessive pressure causes overpacking and internal stress, while insufficient pressure fails to compensate shrinkage. A methodical approach involves setting packing pressure at 40-60% of switchover pressure, then incrementally increasing packing time while monitoring part weight. Weight stabilization indicates the solidification point, concluding the packing phase. Subsequent evaluations may justify higher pressures or packing profiles.

The residual melt cushion—remaining material at the screw tip after packing—ensures effective pressure transmission to the cavity for shrinkage compensation. However, excessive cushion size wastes material and extends cycle time. Optimal cushion size ranges between 10-15% of screw diameter.

KRAIBURG TPE materials offer extensive possibilities for injection molding applications. Through proper machine selection, optimized screw design, precise parameter control, and effective residual melt management, manufacturers can fully leverage these materials to produce high-performance, reliable plastic components.

• Mold Design: Critical factors include material shrinkage rate, cooling rate, and venting requirements
• Cooling Systems: Uniform cooling minimizes warpage and distortion
• Ejection: Proper ejection methods prevent part damage during demolding
• Material Storage: Store in dry, cool conditions away from direct sunlight
• Safety: Follow all safety protocols including proper ventilation and PPE

• Typical processing temperatures: 160°C to 240°C (material-specific)
• Bubble prevention: Material drying, reduced injection speed, improved venting
• Surface finish improvement: Polish mold surfaces, optimize parameters, select higher-flow materials

Initial production of automotive interior parts using KRAIBURG TPE encountered warpage issues. Investigation revealed inadequate cooling system design and improper packing pressure. Corrective measures included cooling system optimization for uniform temperature distribution and packing pressure adjustment, ultimately resolving quality issues and improving production efficiency.

The growing emphasis on sustainability drives development of bio-based TPE materials. Advancements in smart manufacturing continue to enhance injection molding through increased automation and process intelligence, promising improved efficiency and product quality.