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Do not correct a blow molding defect from appearance alone. Contain the suspect parts, record the first failing cycle and compare the process with an approved baseline. Decide whether the fault follows one side, one cavity, one mold, one resin lot or the entire machine. Check utilities, actual temperatures, parison behavior, mold closing, blow air and cooling before changing a recipe. Change one variable at a time, mold enough cycles to reach a stable condition, and verify the result with part weight, wall measurements and the required functional test.

Good extrusion blow molding mold design begins with the finished part and acceptance tests. The tool designer then sets the parting line, pinch-off and flash pockets; positions vents and cooling circuits; defines neck and blow-pin interfaces; selects inserts and mold material; and checks mold width, height, thickness, opening and clamp requirements against the machine. Freeze the mold only after the machine supplier, mold maker and buyer approve the same drawing and trial conditions.

Build the plan around the actual machine manual and production conditions. Inspect safety systems, leaks, oil level and temperature, air and water conditions, extrusion stability, tooling, lubrication, electrical cabinets, sensors and alarm history. Record trends and plan corrective work before a small change becomes unplanned downtime.

Ask for the project-specific utility sheet and general arrangement drawing. Confirm connected electrical load, expected operating load, voltage and frequency, compressed-air pressure and flow, cooling-water pressure, temperature, flow and quality, drainage, machine weight, floor loading, ceiling height, lifting access, exhaust, material handling, and downstream equipment.

Start troubleshooting by recording the alarm, operating mode and current machine position. Compare set values with actual feedback, then check the relevant input, output and permissive conditions. Reset only after the cause is understood and the area is safe.

A parison controller varies die-gap opening through the extrusion cycle. The profile must match part geometry, resin behavior, parison length, blow timing, tooling zero and span, and—on an accumulator machine—the accumulator position. Change one variable at a time and verify the molded part.