Mold design is the key bridge connecting product creativity and mass production. A rigorous evaluation can prevent 80% of mold testing failures. This article focuses on non-tabular key technical logic and provides in-depth analysis based on pain points in industrial scenarios.
A medical device company experienced a 37% scrap rate due to sudden changes in wall thickness (1.5mm → 4mm) in connecting components.
Main wall thickness to rib thickness ratio ≤ 2:1 (e.g., when the main wall thickness is 2mm for PC material, the rib thickness must be ≤ 1mm)
Use a gradual slope for thick-walled transition zones (thickness increase per millimeter must not exceed 30%)
A car grille part with surface etching (VDI 3400 standard) failed to add compensation draft angles, resulting in ejection damage.
For every 0.01mm increase in texture depth, the draft angle must be increased by an additional 0.5°
Deep cavity structures (>50mm) require two-stage draft angles: 3° at the entrance → 5° at the bottom
A certain drone housing used an edge gate, with the weld line running through the stress zone:
High-appearance-requirement parts: prioritize hot runner needle valve gates (to eliminate flow marks)
Glass-fiber reinforced materials: Avoid point gates (fiber breakage leads to strength degradation)
A mold temperature difference of 5°C can increase the warpage of an automotive lamp cover by 0.8mm:
Cooling channels in critical areas must be within 12mm of the cavity surface
Independent temperature control for moving and fixed mold water (e.g., fixed mold at 40°C / moving mold at 60°C to balance shrinkage.
A connector mold made of S136 steel for producing PPS + 40% glass fiber parts experienced severe gate erosion after 230,000 mold cycles:
Materials with over 30% glass fiber content must use powder metallurgy steel (e.g., ASP23)
Corrosive materials (e.g., PVC) require nitrogen-containing stainless steel (e.g., STAVAX ESR)
A slanting ejector pin in an appliance mold broke, requiring disassembly of the entire mold frame for removal:
Moving parts must be designed modularly (replaceable within 30 minutes)
Install sensors on the ejector plate to monitor reset status
Fill pressure red line: Exceeding 85% of the injection molding machine's max pressure requires immediate modification of the gate system
Melt front temperature: A drop exceeding 15°C indicates a risk of stagnation
Air pocket location: If air pockets appear on assembly or exterior surfaces, add additional venting
A smartphone frame developed burn marks due to insufficient venting at the end of the rib:
Vent slot depth = material viscosity coefficient × 0.03 (e.g., 0.025 mm for ABS)
1 mm vent perimeter required per 100 mm² cavity area
A daily-use product mold experienced a 28% cycle time increase due to uneven cooling:
If cooling time accounts for over 60% of the cycle, the cooling channel layout must be reoptimized
Each 10 mm increase in ejection stroke adds 0.7 seconds to mold opening/closing time
HASCO standard mold bases reduce machining costs by 40%
Standardized ejector pin specifications reduce spare parts inventory by 70%
Original Design Defects:
Side gates caused uneven fiber orientation
Insufficient core cooling resulted in deformation exceeding tolerance by 0.5mm
Insufficient venting at the parting line caused burning
Modification Plan:
Converted to a valve-type hot runner with three-point injection
Embedding beryllium copper inserts to accelerate core cooling
Adding 12 venting grooves with a depth of 0.015mm
Results: Deformation ≤0.08mm, yield rate increased from 65% to 98%
Flow Balance: Does the melt front arrive at the end simultaneously?
Thermal Management: Is the temperature difference between the moving and fixed mold halves controlled within a reasonable range?
Demolding Risk: Do all undercuts have corresponding mechanical solutions?
Disaster Prevention: Is there an automatic shutdown mechanism for mold pressure/temperature control abnormalities?
Cost Anchor: Can standard parts replace custom parts?
Industry adage: An excellent mold is not designed; it is “forged” through systematic evaluation. Each evaluation is a preemptive battle against mass production failures. Companies that lose the evaluation battle will eventually bleed out in the workshop.
