Three-Station Rotary Injection Mold Positioning Calibration Specification Introduction

Three-station rotary injection molds are widely applied in multi-color molding, insert embedding, and alternating forming production, relying on precise rotation, positioning, and locking of the rotary table to realize synchronous multi-process molding. Compared with conventional two-plate and three-plate molds, three-station molds impose extremely high requirements on rotary table parallelism, coaxiality, positioning accuracy, and mold clamping clearance. Minor positioning deviation will directly trigger product dislocation, flash, part crushing, incomplete filling, dimensional out-of-tolerance, and even severe mold collision accidents. To unify standard procedures for processing, assembly, trial molding, and mass production calibration, and standardize positioning and correction operations of three-station rotary molds, this technical specification is formulated.

I. Basic Assembly Precision Calibration Standard for Rotary Tables

The rotary table serves as the core moving component of three-station molds, and its assembly precision determines the molding consistency of the entire mold. After rotary table machining, benchmark leveling calibration is implemented first to ensure the flatness and parallelism of the rotary table meet tolerance standards for three-station molds. The reference surface of the rotary table shall be fully ground, with flatness tolerance controlled within 0.01mm, free of high points, edge collapse, and machining textures.

During assembly, the parallelism between the rotary table and moving plate is strictly calibrated, with the height difference error of four corners not exceeding 0.015mm, to prevent uneven mold clamping stress caused by height deviation during rotation. The central bearing position and rotary shaft sleeve of the rotary table undergo matching grinding, with fitting clearance maintained at 0.01mm to 0.02mm. Excessive clearance leads to shaking during rotation, while insufficient clearance causes jamming and delayed rotation positioning.

All fixing screws are tightened evenly in diagonal multiple passes to avoid micro-deformation of the rotary table from one-sided locking. After assembly completion, manually rotate the rotary table to verify smooth movement without jams, shaking, or abnormal collision noise; only stable operation qualifies the mold for positioning mechanism calibration.

II. Precision Position Locking Mechanism Calibration Standard

Three-station molds adopt positioning pins, positioning cones, locking blocks, and mechanical clamping to achieve precise station alignment, forming the core focus of calibration work. Each station corresponds to an independent positioning structure, and the positioning depth, angle, and taper of the three stations must be completely consistent.

The conical fitting surface of positioning cones shall achieve over 90% uniform contact, eliminating one-sided contact and idle clearance. Positioning pins shall slide smoothly without jamming or offset, and the lateral shaking volume of the rotary table after full positioning shall not exceed 0.01mm. Mechanical locking blocks shall fully close with unified locking stroke calibration, and the locking depth error of the three stations is strictly limited within 0.02mm.

For common defects including slight dislocation, offset, and mold clamping deviation of rotary tables, the shim adjustment method is adopted to correct station deviation by increasing or decreasing the thickness of positioning shims, ensuring uniform height of cavity centers and flat parting lines of the three stations. Forcible hard locking and violent alignment are prohibited, which will deform positioning structures and cause permanent precision failure.

III. Coaxiality and Equal-Angle Station Calibration Standard

Three-station molds adopt a 120° equal-angle three-station structure, and angle deviation is the primary inducement of molding dislocation. Calibration uses dial indicators, angle gauges, and height gauges for precision measurement and adjustment.

First, calibrate the central coaxiality of the rotary table; the coaxial error between the rotary center and mold main center shall be ≤0.015mm, eliminating accumulated offset errors from eccentric rotation. Second, calibrate the 120° equal division angle, with the angle error of three stations not exceeding ±0.02°. Excessive angle deviation directly results in multi-color product offset, sealing dislocation, and assembly dimensional defects.

Measure the cavity center distance, ejection center, and gate center station by station to guarantee fully symmetric structure and consistent stress of the three stations. If offset occurs in a single station, fine-tune the position of positioning cones and holes to unify the reference of the three stations, ensuring complete coincidence of cavity positions after each station switching rotation.

IV. Parting Line and Mold Clamping Clearance Calibration Standard

Three-station rotary molds often face inconsistent tightness of mold clamping across stations, incomplete compression of parting lines, and local flash, requiring unified mold clamping calibration standards.

Before mold clamping, inspect the flatness of all station parting lines, removing protrusions, iron filings, and foreign objects. Red lead compound fitting inspection is adopted to check the bonding rate of parting lines, requiring uniform full-surface contact without local idle clearance and partial crushing. The overall mold clamping clearance is uniform, with the clearance error of three stations controlled within 0.01mm, eliminating the defect of one tight station and two loose stations or vice versa.

Focus on calibrating the edge of the rotary table, insert joints, and positioning gaps to prevent displacement, shifting, and material overflow under high-pressure injection. After mold clamping, manually inspect smooth coordination of all guide pins and guide sleeves without eccentric wear and mold jamming risks, ensuring stable alternating high-speed production.

V. Dynamic Rotation and In-Place Signal Calibration Standard

Beyond static precision calibration, three-station rotary molds must complete dynamic operation calibration to adapt to automated machine production.

The rotary table rotates at uniform speed with stable start and stop, free of jitter and inertial overshoot. After each rotation in place, mechanical positioning and electronic induction signals are matched synchronously; the induction distance of sensors is uniformly calibrated to eliminate signal delay, false alarms, and missing signals. The system accurately identifies the current station after station switching, eradicating hidden dangers including station disorder, repeated positioning, and dislocation mold clamping.

Continuous no-load rotation for 50 cycles without deviation, jamming, or signal abnormalities qualifies the mold for trial molding production.

VI. Re-Inspection and Maintenance Standard for Positioning During Trial Molding and Mass Production

Complete re-inspection of rotary table positioning is mandatory after initial trial molding, mold modification, and long shutdown restarts. During trial molding, observe product dislocation, flash, thickness deviation, and uneven sealing of three stations; immediately shut down to fine-tune positioning structures once single-station defects appear.

During mass production, regularly calibrate rotary table parallelism, positioning clearance, and locking precision, cleaning iron filings and oil stains from positioning grooves to maintain tight fitting of positioning structures. Precision re-inspection is conducted every 30 days to prevent station offset and precision attenuation caused by long-term rotational wear.

Conclusion

The core of three-station rotary injection mold positioning calibration lies in flatness leveling, equal-angle calibration, gap-free positioning locking, precise coaxiality, and stable dynamic operation. As the core mechanism for alternating multi-station molding, the static assembly precision and dynamic alignment accuracy of rotary tables directly determine product yield and mold safety coefficient. Strict implementation of this calibration specification thoroughly resolves common three-station mold defects including dislocation, offset, flash, and crushing, significantly improving the stability and consistency of multi-color and multi-station injection production while extending mold service life, applicable to processing assembly, acceptance debugging, and daily maintenance of all three-station rotary injection molds.