Technical Document: Single-Cavity, Multi-Cavity, and Precision Test Molds
Test molds are core equipment for material R&D, product performance verification, and production process optimization. Their structural design and precision control directly determine the consistency and accuracy of test samples, which in turn affect the reliability of subsequent material performance tests (e.g., tensile, bending, impact, thermal deformation). As the most widely used types in the industry, single-cavity, multi-cavity, and precision test molds adapt to scenarios with different R&D stages, production scales, and precision requirements, playing an irreplaceable role in plastics, rubber, composite materials, metal powder injection molding, and other fields. This document systematically elaborates on the core technical content of the three types of molds from structural characteristics, key parameters, application scenarios, and technical trends, providing references for industrial applications.
I. Single-Cavity Test Mold
Structural Design and Core Technical ParametersSingle-cavity test molds adhere to the core design concept of "precise adaptation and rapid commissioning," consisting of mold core, mold sleeve, gating system, cooling/heating system, and guiding and positioning mechanism. Cavity structures strictly comply with industry standards such as ASTM, ISO, and GB/T, with common sample types including standard tensile bars (e.g., ISO 527-2 Type 1A), bending samples (ISO 178), and impact samples (ISO 180). Key technical parameters: cavity dimensional tolerance controlled at ±0.01mm, cavity surface roughness Ra≤0.8μm, heating system temperature fluctuation ±2℃, cooling system cooling rate 0.5-5℃/min, and guiding mechanism with ball guide pillars and bushes achieving positioning accuracy ≤0.005mm.
Application Scenarios and Production AdaptabilitySingle-cavity test molds are mainly suitable for early R&D stages, small-batch verification, and special material testing. In new material formula R&D, mold cores can be quickly replaced to prepare samples of different specifications, with commissioning cycles shortened to 2-4 hours. For heat-sensitive materials (e.g., PVC, PA66) or high-performance composites (e.g., carbon fiber-reinforced PEEK), the single-cavity structure avoids molding defects caused by uneven runner flow in multi-cavity molds, improving sample qualification rate. These molds are compatible with small and medium-sized injection molding machines (clamping force 50-150T) and vulcanizers, weighing ≤50kg for easy manual handling and installation. Modular design reduces the replacement cost of wearing parts (e.g., mold cores, sprue bushings) by 30% and shortens maintenance cycles to 1-2 days, meeting the high-frequency commissioning needs in R&D.
Technical Optimization TrendsCurrent technical upgrades of single-cavity test molds focus on "flexibility" and "intelligence." For flexibility, quick-change mold core structures are adopted, with core replacement time ≤30 minutes via locating pins and buckles for rapid switching of multi-specification samples. For intelligence, temperature and pressure sensors are integrated to real-time monitor internal cavity temperature (accuracy ±0.5℃) and molding pressure (accuracy ±0.1MPa), with data synchronized to production management systems for process traceability and optimization.
II. Multi-Cavity Test Mold
Cavity Layout and Synchronization ControlMulti-cavity test molds focus on "efficient mass production and consistency control," with cavity layouts in parallel or matrix designs, commonly available in 2-cavity, 4-cavity, 8-cavity configurations, and expandable up to 16 cavities. Layout design follows the runner balance principle, with main and branch runners of equal length and cross-section to ensure cavity filling time difference ≤5%. Synchronization control is achieved through three key points: hot runner systems with nozzle temperature fluctuation ±1℃ to avoid uneven filling due to melt cooling; independent cavity venting mechanisms with vent gap 0.01-0.02mm for consistent venting efficiency; and cavity dimensional consistency control with inter-cavity deviation ≤0.02mm and sample weight deviation RSD ≤3% to meet data comparability requirements for batch testing.
Core Advantages and Application Scenarios for Batch TestingMulti-cavity test molds offer core advantages in efficiency improvement and cost control. Compared with single-cavity molds, 4-cavity molds increase sample output efficiency by 3-4 times, 8-cavity molds by 6-7 times, and reduce unit sample production cost by 20%-40%. Mass-produced samples have higher consistency, reducing test data dispersion and improving the reliability of material performance evaluation. Application scenarios include pilot-scale batch verification, multi-batch process comparison tests, and large-scale material performance testing. In scenarios such as automotive component material verification and electronic device housing material selection, hundreds or thousands of standard samples are required for fatigue and environmental aging tests, where multi-cavity molds significantly shorten test cycles. These molds are compatible with medium and large injection molding machines (clamping force 150-300T), supporting continuous production with daily capacity up to thousands of pieces.
Key Technical Breakthroughs and Development DirectionsRecent technical breakthroughs of multi-cavity test molds focus on "precision temperature control" and "intelligent monitoring." Precision temperature control adopts zone-controlled hot runner systems, allowing independent temperature adjustment of each cavity nozzle to adapt to melt flow characteristics. Intelligent monitoring integrates cavity pressure and displacement sensors to real-time feed back filling status, with automatic alarms when inter-cavity filling difference exceeds 5% to avoid batch production of unqualified samples. Development trends include modular cavity design for adjustable cavity quantity to improve mold reusability, and integration of digital twin technology for 3D modeling and simulation to optimize runner layout and temperature control parameters, shortening commissioning cycles by over 30%.
III. Precision Test Mold
High-Precision Implementation Path and Core IndicatorsPrecision test molds target high-end material R&D and high-demand performance testing, focusing on "micron-level precision and super-high quality." High precision is achieved through full-process control: mold cores are processed via CNC grinding + EDM, with machining accuracy up to ±0.003mm and cavity profile tolerance ≤0.005mm; surface treatment adopts nitriding (hardness ≥HRC60) or diamond coating (thickness 3-5μm), resulting in surface roughness Ra≤0.2μm to ensure scratch-free and non-sticking samples. Core technical indicators: dimensional tolerance ±0.005mm, geometric tolerance ≤0.003mm, sample thickness uniformity ≤0.01mm, and thermal stability ≤0.002mm/℃ (within -40℃-120℃). High-precision guiding mechanisms and locating pins ensure mold clamping repeatability ≤0.002mm, avoiding sample defects caused by clamping deviation.
Core Application Scenarios and Material AdaptabilityPrecision test molds are mainly used for high-end material verification and precision component performance testing, typical scenarios including aerospace composites (e.g., carbon fiber-reinforced epoxy resin), electronic-grade engineering plastics (e.g., LCP, PPSU), and medical-grade materials (e.g., implantable PEEK). These materials demand extreme sample dimensional accuracy and surface quality—for example, dimensional deviation exceeding 0.01mm in tensile strength test samples of aerospace composites may lead to test result deviation over 5%, affecting material selection. Material adaptability covers high-temperature molding materials (molding temperature ≤350℃), high-viscosity materials, and micro-nano structured samples, supporting micro-runner design (runner diameter ≥0.5mm) and preparation of ultra-thin samples with minimum thickness 0.1mm for microelectronics and medical device testing.
Technical Trends and Industry AdaptabilityTechnical trends of precision test molds focus on "ultra-precision machining" and "digital empowerment." Ultra-precision machining uses nano-level equipment (machining accuracy ≤0.001mm) for precise molding of micro-nano cavity structures. Digital empowerment integrates CAD/CAE/CAM technology to realize full-process digital control from design and simulation to manufacturing, reducing human errors. Intelligent monitoring is upgraded with laser displacement sensors and infrared thermometers for real-time monitoring of sample dimensional changes and temperature distribution, with data sampling frequency ≥100Hz for precise process optimization. Industry adaptability drives development towards "customization" and "multi-material compatibility," optimizing mold structures for specific material molding characteristics and adapting to testing needs of materials from thermoplastics to ceramic matrix composites, supporting high-end product R&D and performance breakthroughs.
