Core Inspection Items for Injection Mold DFM Analysis

DFM manufacturability analysis is a necessary pre-development review for injection molds. It effectively identifies unreasonable product structures and potential molding risks before mold opening, avoids massive mold modifications after processing, shortens project cycle and improves mass production yield. Standard DFM inspection covers structural rationality, molding feasibility, mold mechanism, cooling ejection and machining practicability, forming systematic core verification items.

1. Wall Thickness and Rib Structure Inspection

Wall thickness uniformity is the primary inspection standard. The conventional wall thickness of plastic parts is controlled between 0.8mm and 3mm, and the thickness difference of the same part shall not exceed 20% to prevent shrinkage depressions, bubbles and deformation. The thickness of reinforcing ribs is controlled at 0.5 to 0.7 times the main wall thickness with rounded transition at the root to avoid accumulated material shrinkage. Excessively high and thin ribs are optimized to prevent incomplete filling and cracking. Thick-wall areas greater than 3mm are hollowed out to reduce cooling time and internal vacuum defects. The wall thickness of screw columns and positioning bosses keeps uniform with the main body to ensure structural stability.

2. Demolding Draft and Fillet Structure Inspection

Sufficient demolding draft is the key to avoid product scratching and whitening. The draft angle of high-gloss and textured appearance surfaces is increased according to grain depth, while the minimum draft of inner non-appearance surfaces is guaranteed above 0.5°. All sharp corners are optimized with rounded corners to reduce stress concentration and improve melt fluidity. For undercut positions requiring slides and lifters, the moving space and structural feasibility are verified in advance. The penetrating matching surface reserves standard draft to prevent long-term wear and flash generation of mold parts.

3. Hole Position, Boss and Buckle Structure Inspection

The depth-diameter ratio of blind holes is standardized to avoid slender insert pin breakage. The structural strength of screw bosses is checked, and anti-shrinkage grooves and anti-rotation structures are optimized to prevent column cracking and thread slipping during assembly. The elasticity and assembly allowance of buckles are verified to avoid fracture or loose clamping. The assembly clearance of positioning stops is reasonably reserved to ensure precise fitting of finished products. For embedded metal parts, the wrapping thickness and anti-offset structure are checked to prevent injection molding deviation.

4. Appearance and Molding Defect Risk Prediction

DFM analysis accurately predicts weld line positions, air trap areas and shrinkage risk points. The scheme of adjusting glue inlet position is adopted to transfer weld lines to non-key appearance areas. For closed grooves and deep rib areas prone to trapped air, exhaust structure layout is reserved in advance. For asymmetric structures easy to warp, wall thickness balance and reinforcing rib optimization are proposed to control deformation. The process feasibility of mirror surface, texture and spray-free appearance is verified to avoid demolding whitening and uneven texture.

5. Gating System and Mold Cavity Layout Inspection

According to product appearance and structural characteristics, reasonable gate types and feeding positions are selected. Appearance parts adopt hidden gates to avoid surface traces. The flow channel balance is optimized to ensure uniform filling and stable injection pressure. For large-area flat parts, multi-point feeding is matched to reduce warpage deformation. The sealing distance around the gate is checked to prevent high-pressure flash, and hot runner feasibility is evaluated for high-precision appearance parts.

6. Mold Mechanism, Cooling and Ejection Inspection

The moving stroke and interference of slides and lifters are fully checked to ensure stable undercut demolding. The layout of cooling water channels is standardized to keep uniform cooling distance and reduce product shrinkage difference. The ejection position is reasonably arranged to avoid top whitening and top deformation. Key deep cavity and thin-wall structures are equipped with targeted waterway optimization and auxiliary ejection schemes to improve molding qualification rate and production stability.