Technical Specification and Application Guide for Single-Cavity and Multi-Cavity Specimen Test Molds
Definition and Core Functions: Specimen test molds are key equipment in material performance testing. They precisely simulate actual production molding processes to produce test specimens complying with ISO, GB, and other international and domestic authoritative standards, providing a standardized foundation for testing key indicators such as tensile strength, impact toughness, and bending performance.Single-cavity specimen test molds produce one standard specimen per injection molding cycle with a simple structure. Multi-cavity specimen test molds can simultaneously produce two or more specimens of the same specification, among which 4-cavity and 8-cavity configurations are most widely used in industrial testing.Both types of molds must strictly control the dimensional accuracy and surface quality of specimens to avoid distorted test data caused by sample defects, which could affect material evaluation and product R&D decisions.
Industry Applications and Technical Trends: With the rapid iteration of high-end manufacturing fields such as new energy vehicles, aerospace, and consumer electronics, the market has higher requirements for material performance testing accuracy and efficiency, leading to a continuous increase in demand for specimen test molds.Current industry technology development focuses on three directions:First, precision control advances toward the micron level to meet the high-precision testing needs of special materials;second, modular design becomes mainstream, enabling rapid switching of tests for different specification specimens through replaceable components to improve mold versatility;third, intelligent upgrading accelerates, integrating sensors for temperature, pressure, etc., to achieve real-time monitoring and data tracing of key molding parameters, facilitating the in-depth integration of intelligent manufacturing systems.
I. Structural Design and Core Parameters
Basic Structural Composition: Both types of molds consist of core components including mold bases, cavities, cores, cooling systems, and runner systems. The material and design rationality of each component directly affect specimen quality.Mold bases are mostly made of cast iron or aluminum alloy. Due to its lightweight advantage, aluminum alloy's application ratio in small and medium-batch testing scenarios is gradually increasing;as key components directly contacting molten materials, cavities and cores are preferably made of S136H stainless steel or H13 tool steel, which have excellent wear resistance and corrosion resistance. After fine polishing, their surface roughness can reach Ra≤0.2μm, effectively reducing surface scratches and defects on specimens.Cooling systems need to be designed with runner layouts based on the thermal performance characteristics of test materials to ensure uniform cooling of specimens during molding and avoid internal stress or deformation caused by temperature gradients.
Specialized Design for Single-Cavity Molds: Leveraging their simple structure, single-cavity molds excel in parameter stability control.Their cavity dimensions strictly follow standard specimen specifications, adopting submarine gates or pin gates to reduce the impact of gate marks on specimen performance.In terms of molding process parameters, precise regulation of holding pressure and cooling time further ensures specimen curing quality, making them particularly suitable for high-precision testing scenarios sensitive to parameter fluctuations, such as testing of aerospace special alloy materials and medical polymer materials.
Specialized Design for Multi-Cavity Molds: The core design challenge of multi-cavity molds is solving the synchronization problem of each cavity.To ensure uniform filling of each cavity with molten materials, a balanced runner system is adopted, and the cavity spacing is controlled within a reasonable range to ensure uniform heat dissipation;high-precision temperature control systems are equipped to effectively avoid specimen dimensional deviations caused by temperature fluctuations.In addition, some high-end multi-cavity molds support flexible switching between 2 to 16 cavities. By replacing cavity modules, they meet different batch testing needs and significantly improve testing efficiency in large-scale production scenarios.
II. Performance Comparison and Scenario Adaptation
Core Performance Differences: In terms of precision, single-cavity molds have better specimen dimensional repeatability due to more uniform force, better meeting high-precision testing needs;while multi-cavity molds have significant advantages in mass production efficiency, the increase in cavity quantity raises the difficulty of parameter regulation, resulting in slightly lower dimensional repeatability than single-cavity molds.In terms of maintenance costs, single-cavity molds have fewer components, lower failure rates, and longer maintenance cycles;multi-cavity molds require regular calibration of cavity synchronization, leading to relatively higher maintenance frequency.
Typical Application Scenarios: Single-cavity molds are mainly suitable for small-batch, high-precision testing needs, such as R&D testing of special materials in the aerospace field and performance verification of medical rubber products;at the initial stage of material R&D, they can quickly adjust process parameters to provide accurate data support for formula optimization.Multi-cavity molds are widely used in quality control links of mass-produced products such as auto parts and consumer electronics, such as batch testing of auto sealant materials and performance screening of mobile phone shell materials;while ensuring testing quality, they can effectively reduce the manufacturing cost per specimen.
Selection Principles: Mold selection needs to comprehensively consider three core factors: production batch, precision requirements, and cost budget.When the daily test specimen volume is small and precision requirements are strict, single-cavity molds are preferred;when the test volume is large and precision requirements are within the conventional range, multi-cavity molds are more economical.In addition, mold selection should be based on the characteristics of test materials. For composite materials with poor fluidity (such as glass fiber-reinforced plastics), single-cavity or small-cavity molds are recommended to avoid specimen scrap caused by uneven filling.
III. Manufacturing and Usage Specifications
Manufacturing Process Requirements: Mold processing uses precision CNC equipment throughout to ensure cavity dimensional accuracy and assembly precision;during the assembly of key components, professional positioning tools are used to ensure the fit between cavities and cores, avoiding flash caused by gaps.For multi-cavity molds, strict runner balance tests are required before delivery to ensure the filling time difference of each cavity is controlled within a reasonable range;simultaneously, the cavity surface is nitrided to reach a hardness of HRC58-62, significantly extending the mold service life.
Operation and Maintenance Specifications: The specimen preparation environment must meet strict temperature, humidity, and cleanliness standards to avoid environmental factors affecting specimen quality;the raw material preprocessing link is crucial, and the drying temperature and time for different materials must strictly follow industry specifications. For example, PA materials need to be dried at a specific temperature for a certain period to ensure the moisture content meets the standard.In daily maintenance, the residual material on the cavity surface should be cleaned daily, the smoothness of the cooling system checked weekly, and the temperature and pressure control systems calibrated monthly;if the mold is out of service for more than 72 hours, anti-rust oil should be applied to the cavity surface for protection.
Quality Control Points: All specimens must be inspected after molding, with key dimensions measured using high-precision measuring tools;appearance inspection should reject samples with defects such as bubbles, flash, and cracks. For notched specimens, the notch area should be carefully checked with a magnifying glass to ensure no microcracks.At least 3 parallel samples should be prepared for each test item to ensure the repeatability of test data meets industry standards;meanwhile, a complete batch record file should be established, detailing mold parameters, raw material information, test results, etc., with a retention period of no less than 2 years to facilitate subsequent quality tracing and problem troubleshooting.
