PET Preform Mold Design Guide

Begin with the latest controlled preform drawing or an identified sample. Record the target weight, PET resin grade, color or additives, bottle application and the drawing revision used for quotation. These inputs define the part shot, visible requirements and the reference for later inspection. If any value is provisional, label it as an assumption and name who must approve the final value before the mold definition is released.

• Reference one current drawing revision
• Record weight and material basis
• Separate approved data from assumptions

Use the complete neck-finish drawing together with the intended cap, pump or lid information. Review thread, sealing surface, tamper feature, support or transfer ring and downstream handling as one interface package. A familiar neck name identifies a family, but the controlled revision and actual closure establish compatibility and the neck-component acceptance checks.

• Match neck and closure revisions
• Identify seal and tamper interfaces
• Define closure-fit evidence

Translate required saleable output into candidate cavity counts using the same approved preform and operating basis. Compare total shot, stack spacing, mold width and height, runner routing, cooling access and replaceable-component access for each candidate. The selected count is the supported layout that fits the intended machine and maintenance plan, not simply the largest number in a catalog.

• Use one output basis
• Show proposed stack spacing
• Check mold envelope and service access

The runner review identifies manifold and nozzle arrangement, heating and sensing zones, valve-gate actuation, connectors, controller responsibility and critical service parts. The proposal should show how the system relates to the cavity layout and approved preform. Trial records then provide the project-specific basis for reviewing gate condition and fill behavior without relying on an unsupported general performance promise.

• Define zones and interfaces
• State actuation and controller scope
• List critical runner spares

Review cooling passages around the core, cavity and neck components together with inlet and outlet arrangement, circuit identification and the buyer's available water temperature, pressure and flow. Cycle discussion must state the resin, part, machine and utility conditions used. A drawing and recorded trial basis make cooling changes traceable when temperature or dimensional variation appears.

• Map and identify circuits
• Record plant-water conditions
• Tie cycle evidence to stated conditions

Plan how samples will be identified by cavity and compared for the agreed weight, gate, appearance and selected dimensions. The review should distinguish runner or process imbalance from isolated component or cooling issues. Acceptance sampling, measurement methods and decision limits come from the approved project specification rather than an invented universal tolerance.

• Keep samples cavity-traceable
• Use agreed measurement methods
• Assign action for outlying cavities

Compare the proposed mold with the exact injection unit, total shot and plasticizing basis, platen and tie-bar space, mold-height range, opening movement, take-out clearance, hot-runner controls and plant utilities. Record adapters or buyer-supplied work in an interface schedule so the mold configuration and installation plan use the same machine data before order approval.

• Use the exact machine configuration
• Check physical and injection fit
• Assign every control and utility interface

Define the trial machine, PET resin, approved drawing revision and recorded operating condition before samples are produced. Identify the required full-cavity sample set, measurement and visual checks, trial images or video, corrective-action record and shipment-release documents. The commercial agreement should state who performs each check and what evidence closes an open acceptance point.

• Freeze the trial basis
• Identify samples and inspection records
• Close corrective actions before release