Design Standards for Precision Injection Molds
2026-04-15 15:42:54
Precision Injection Molds
Precision injection molds are used to produce high‑precision plastic parts for electronics, medical devices, optics and automotive industries. Such molds require extremely high dimensional accuracy, stability, surface quality and service life. The design must follow strict standards to ensure consistent part quality in mass production. This article summarizes the complete design standards for precision injection molds.
Precision Control StandardsPrecision control is the core of precision mold design. Cavity and core tolerances reach IT3–IT5 level, and mold dimension tolerance is controlled to 1/3 to 1/5 of the part tolerance. Template flatness, parallelism and perpendicularity must be strictly controlled. Guide pillar and bushing matching accuracy reaches H5/g4 or higher, with very small clearance.
Repeat positioning accuracy is less than 0.01mm to ensure consistent product size. Mold deformation under injection force must be controlled within 0.002mm to avoid size deviation. All design and processing must be based on micron‑level precision to meet the requirements of high‑precision parts.
Structure Design Standards
The mold structure must be stable and rigid to reduce deformation under high pressure. Parting surface design should be simple and reliable to avoid flash and poor matching. Sliders and lifters require precise matching clearance to ensure smooth movement and accurate positioning.
Wear compensation should be reserved for long‑term production. The mold should be easy to disassemble, maintain and inspect. Reasonable support and reinforcement structures help improve overall rigidity and stability. The structure design directly affects the service life and precision stability of the mold.
Molding System Design StandardsThe molding system includes gate, runner and cavity. Gate size and location should be optimized for balanced filling and low pressure loss. Runner system should be designed to minimize pressure loss and ensure uniform flow. Hot runner temperature control accuracy must reach ±0.5℃.
Cavity surface roughness must be controlled below Ra0.8μm, and optical parts require Ra0.2μm or higher. Proper draft angle helps avoid sticking and scratching. The molding system directly determines filling effect, surface quality and dimensional stability.
Cooling System Design StandardsUniform and conformal cooling channels are essential for precision molds. Water channel diameter and distance should be reasonably designed to ensure uniform heat dissipation. Mold temperature difference must be controlled within ±2℃ to avoid warpage and size deviation.
High heat transfer efficiency helps stabilize molding cycle and improve productivity. Reasonable cooling design can effectively reduce internal stress and improve dimensional stability. The cooling system is one of the key factors affecting precision and efficiency.
Guidance and Positioning Standards
High‑precision guidance and positioning systems are essential for precision molds. Four or more sets of high‑precision guide pillars should be used to ensure stable movement. Centering and positioning structures such as tapered locks help improve positioning accuracy.
Anti‑wear and anti‑collision designs extend service life. Accurate matching with the injection machine nozzle ensures stable injection. The guidance system directly affects the repeat accuracy and service life of the mold.
Material and Heat Treatment StandardsCavity and core materials such as S136, H13 and NAK80 should have high hardness, wear resistance and corrosion resistance, with hardness after heat treatment reaching HRC48–54. Guide components should be made of hardened steel with hardness HRC58–62.
The mold base usually uses P20 with hardness HRC28–32. Materials must be free of defects, and heat treatment must ensure uniform hardness without deformation or cracks. Material selection and heat treatment are fundamental to the stability and life of precision molds.
ConclusionPrecision injection mold design is a comprehensive system involving precision, structure, materials, processing and process. Strict compliance with design standards ensures high precision, stability and long service life, providing a solid foundation for high‑quality plastic parts.
