Mold design is the core link connecting product design and mass manufacturing, and its design principles need to strike a balance between functionality, economy and manufacturability. The following are the core principles and specific practical points of mold design:

First, the principle of functional priority
Accurately reproduce product designs

Cavity size should include material shrinkage compensation (e.g. ABS shrinkage 0.5%-0.7%)

Tolerance control of key features: the appearance surface of electronic products ± 0.02mm, and the structural parts ± 0.05mm
Case: The automobile lamp cover mold is designed with a negative shrinkage rate to offset the shrinkage of PC material molding

Reliable release mechanism

Demoulding slope design: the appearance surface is 1°~3°, and the internal structure is 0.5°~1°

Ejection system layout: the diameter of the ejector pin is ≥ φ2mm, and the spacing is not more than 50mm
Example: Medical catheter mold is demolded with pneumatic ejection and silicone soft top combination

Second, the principle of structural rationality
Optimized design of parting surface

Preferential selection of plane parting (to reduce the difficulty of machining)

Normal continuity during surface parting (avoid flash)
Tesla window trim molds use 3D laser scanning to determine the optimal parting line

Balance between rigidity and lightweight

Calculation of template thickness: L=(0.12~0.15)× mold width

Weight reduction design: digging weight reduction groove in non-bearing area (depth≤ 1/3 of plate thickness)
The mold of the 900T injection molding machine adopts a grid-like stiffener design, which reduces the weight by 15%

3. The principle of manufacturability
Process constraints Design countermeasures
CNC Machining Limitations: Avoiding Inner Right Angles (R≥0.5mm)
EDM Gap Electrode scaling compensation 0.1-0.3mm/uniside
Polishing accessibility deep cavity inclination angle ≥ 30°
Case: The high-gloss cosmetic cap mold uses mirror spark pattern processing instead of manual polishing

4. the principle of economy
Cost control strategy

Standardization of formwork (Longji LKM standard series)

Insert design: SKD61 inserts for vulnerable areas (reduce costs)
Through modular design, the mold cost of a home appliance panel is reduced by 40%

Optimization of mass production efficiency

Hot runner system selection: needle valve type control multi-cavity balancing

Cooling system design: the conformal cooling channel is 8-12mm away from the profile
The automobile bumper mold adopts a variable pitch cooling channel, and the molding cycle is shortened by 18%

5. The principle of maintainability
Designed for quick repairs

Alignment pin standardization (DME standard)

Quick-change consumables (e.g. spring pre-assembly modules)
The ejector pin system for medical consumables can be quickly changed in 15 minutes

Condition monitoring interface

Set the mounting position for the ejector pin reset sensor

Reserved Mold Temperature Monitoring Point (Type K Thermocouple Interface)
Smart molds use IoT sensors to provide early warning of wear

6. Principles of safety compliance
Machinery safety protection

Moving parts guard (clearance ≤ 6mm)

The cylinder system is equipped with a mechanical locking device

Industry norms are complied with

Medical molds meet ISO 13485 cleanliness standards

Food-grade molds are FDA 21 CFR certified

7. Forward-looking design principles
Modular expansion design

Reserved cavity expansion interface (e.g. phone case mold 1 1→ 2 2)

Standardized hot runner interface (Husky standard)

Intelligent upgrade preparation

Embed the mold identity RFID chip

Setting up the data acquisition interface (OPC UA protocol)

Key design balance points
The golden ratio of precision and cost
Automotive LED lens mold: mirror EDM processing (Ra0.05μm) in key optical areas, and ordinary spark pattern in non-optical areas (30% cost reduction)

The game of life and weight
The heavy-duty mold adopts a double-layer steel plate welded structure, which achieves lightweight under the premise of ensuring a life of 1,000,000 times

The essence of mold design is to find the optimal solution under constraints, and modern design needs to integrate topology optimization algorithms (such as Altair OptiStruct) and process knowledge bases (such as Progressive Die Wizard). Excellent designers should have the ability to feed CAE analysis data (mold flow analysis, structural stress) into design iteration in real time, and realize closed-loop design on platforms such as UG/NX. With the maturity of 3D printing conformal waterway technology, traditional design rules are being redefined.