Contents Covered by DFM Evaluation for Injection Mold Projects
DFM review is a pre-mold evaluation process to identify molding risks, reduce mold revision and defective parts. It connects product structure, molding process, mold design and mass production adaption.
Product structure feasibility assessment
Check draft angle of side walls, ribs and cylinders. Polished and textured surfaces require larger draft to prevent dragging marks. Review wall thickness uniformity, predict sink mark and short shot risk. Evaluate undercut structure and judge whether lifter or slide mechanism is required. Check sharp corners, holes, bosses and ribs to avoid stress concentration and filling defects.
Raw material forming characteristic matching
Assess shrinkage rate, fluidity, heat deformation temperature and moisture absorption property. Glass-filled resin is checked for floating fiber and wear risk, crystalline plastic for directional shrinkage difference. Evaluate shear sensitivity to prevent material degradation near gates.
Gating and venting system review
Confirm gate type and injection point, evaluate melt impact and weld line position. Weld lines should not fall on force and appearance key areas. Check runner balance for multi-cavity molds. Arrange vents at flow ends, weld line positions and deep blind cavities to avoid burning and air traps.
Cooling system layout review
Check channel distance from cavity surface, channel spacing and baffle design. Thick wall and gate zones need priority cooling to reduce warpage and long cycle time. Tiny cores are evaluated for conformal cooling or beryllium copper heat conduction.
Ejection and demolding plan
Estimate packing force, arrange ejector pins, blocks and lifters away from appearance and stress whitening zones. Check synchronization, interference risk and air ejection structure for sticky soft plastic parts.
Parting line and sealing design
Arrange parting lines on non-appearance areas. Evaluate sealing width and structure, predict flash risk for high-pressure thin-wall molding. Check fitting difficulty for step parting surfaces.
Tolerance and dimension chain evaluation
Split shrinkage tolerance, machining tolerance and assembly accumulated tolerance. Differentiate critical functional dimensions and general appearance dimensions. Strict tolerances are communicated for relaxation or mold compensation adjustment.
Machining, assembly and maintenance assessment
Assess machining difficulty of narrow slots and thin steel. Review insert splitting plan for convenient replacement. Check guide structure alignment and disassembly convenience. Hot runner molds review nozzle layout and maintenance space.
Mass production and safety assessment
Verify injection machine tonnage, tie bar space and opening stroke. Check automatic dropping or robot picking interference. Evaluate long-term wear and surface treatment for high-wear zones. Prepare standardized spare parts.
Cost and cycle assessment
Record modification risk cost, compare different schemes and output DFM risk list and improvement suggestions as the basis of drawing revision and mold finalization.
