Tolerance Grades a Toolroom Signs under DIN 16742
DIN 16742 defines nine tolerance grades based on resin shrinkage variance, requiring toolmakers to split tool-bound and parting-line tolerances during sign-off.
DP2 Non Tool Bound
Meaning
Injection mold tolerance categories define dimensional variations across movable parting lines, side actions, and sliding core mechanisms. Classifications marked as dp2 non tool bound apply mid-tier dimensional limits to part features created by two or more moving tool components. Dynamic factors such as clamping force drift and thermal growth of tool slides alter these dimensions during normal press operation.
Material suppliers provide baseline shrinkage estimates, but machine mechanical stability governs the final variance.
Parting Mechanics
Clamping pressure fluctuations directly expand or contract the parting line gap during injection. Operating under dp2 non tool bound parameters requires consistent hydraulic or electric clamp tonnage to minimize parting line deflection. Wear on guide pins and taper locks increases mechanical play between mold halves over time.
Moulders adjust clamp force to balance tool venting against flash formation.
Material Elasticity
Thermal history during cooling influences how much plastic expands across moving tool splits. Utilizing dp2 non tool bound criteria requires precise control over coolant flow rates and barrel temperature profiles. Amorphous polymers like polycarbonate exhibit more predictable post-mould contraction across parting lines than semi-crystalline materials.
High injection pressures can push mold components apart, altering cross-parting line measurements.
Process Boundary
Tool maintenance schedules must account for wear on sliding mechanisms and parting surfaces. Evaluating dp2 non tool bound dimensions involves tracking part thickness variations across multiple production lots. Secondary machining operations become necessary if mechanical tool wear exceeds specified tolerance bands.
Consistent press control maintains dimensional compliance over prolonged manufacturing runs.