PET Preform Mold Design Guide: Key Considerations for Mold Projects

When talking about PET preform mold design, it is helpful to first define the preform you wish to produce, the machinery that will be used and the approved drawings of the same from your design team. This information should be included in the initial enquiry for a final mold proposal.

Bottles and preforms can be designed for our customers and neck rings and cands customized for specific sealing requirements. Additionally, the dimensions and runner layouts of the molds can be designed to match the specific equipment that the purchasing and engineering departments have. Once a preform specification has been established, the discussion can move to the configuration of the mold and then to the approval of drawings and a specific project delivery schedule.

Refer to these review points to prepare your discussion.

Define the Preform and Neck-Finish Requirements

Begin with the proposed preform drawing or an existing sample. Identify which features you want to retain and which you want BJY to review. If the project involves a new preform, ask about BJY’s preform design service as part of the enquiry.

We can customize certain critical features such as neck threads and sealing ring grooves. Please clearly note these features on the drawing package as opposed to listing them under the feature for a “custom mold”.

For your first technical discussion, prepare answers to these questions:

• What preform weight and overall geometry would you like to be quoted on?
• Which neck-finish drawing and revision should the project follow?
• Which thread and sealing features require review?
• Are you requesting the complete mold or the defined component?
• BJY will work from your drawings, an existing sample, or a design request.

Unresolved points should be clearly visible. A requested preform weight e.g. can be marked as target weight until the team and BJY have agreed upon the design. It should also be clearly defined who is approving the final drawing and this approval should be registered before the order is processed.

Review the Main Elements of PET Preform Mold Design

The parts can be made as a single coordinated mold with separate review points for the mold form, cavity, hot runner and cooling.

Core and Cavity

The mold core forms the inside of the preform, including the bore and the inner face of the neck. The cavity shapes the outside. The core also takes heat out of the preform from the inside.

For a mold core enquiry, prepare the relevant component drawings and identify the core specifications that require review before submitting the request.

Check the drawing review for all the internal and external details to be checked. For a component enquiry clearly state the component required and attach the relevant drawing. BJY manufacture preform mold cores to the agreed customer drawing and use this drawing for all subsequent orders of that component.

Reference the prior drawing for a repeat core order and specify if any changes are desired. Confirm with BJY which version of the drawing is to be used for manufacturing.

Cavity Configuration and Equipment Requirements

BJY’s PET preform injection moldes are offered in a variety of flexible multi-cavity configurations. Mould dimensions and runner designs can be adapted to match customer equipment.

Please forward a sketch of the requested cavity configuration and related equipment information to BJY to review for your specific project. The final cavity configuration will be determined by BJY’s review.

Include these points in the discussion:

• What cavity configuration are you requesting?
• What are the key specifications and interface drawings that BJY needs to review?
• What are the proposed mold dimensions and runner design?
• Which design details remain open before drawing approval?

Hot Runner System

Review the hot runner system as a separate part of the PET preform injection mold design, including the proposed layout and its compatibility with the specified equipment.

Please ask BJY to identify the proposed hot runner layout and confirm the scope of work covered by the quotation. Also please confirm the proposed layout against the agreed specifications for the equipment and advise of any further information that the office team require.

Keep the proposal specific: list the requested configuration, the supplier’s proposed arrangement and the drawing revision submitted for approval.

Cooling Arrangement

A well-functioning cooling channel is important for the temperature control of a mold. The cooling is performed by water or oil, mostly water.

Review the cooling arrangement with the mold proposal. Ask which cooling medium is proposed, what channel layout is included and what supply conditions BJY needs your team to confirm. Include cooling of the core in that discussion, since the core also removes heat from inside the preform.

Please let us assess for your project any proposed cooling or production-cycle targets. Conditions and acceptance criteria for your project should first be agreed to before such target becomes a contractual commitment.

Prepare a Clear Enquiry Package

This is a checklist to help you put together your Request for Quotation. Fill in what you can and note the rest for discussion.

Request written confirmation of the open points. When comparing between different versions of a proposal, ensure that you are using the same enquiry reference number and clearly identifying the changes that you are approving.

Confirm Drawings and a Realistic Delivery Schedule

For projects based on an existing sample, the process starts with reverse engineering the customer-provided sample. The resulting 2D/3D drawings are then submitted for customer approval. After approval and order confirmation, the mold proceeds through manufacturing, inspection and shipment.

Before moving forward, confirm who will provide the sample, who will review and approve the drawings, and who will authorize the order. Ask BJY to clarify the stages and responsibilities for your specific project.

Even the fastest preform injection molds require 6 weeks for production. The actual lead time depends on your specific project. We will be happy to confirm the delivery time after going over the requirements with you.

Can you clarify in the quotation when the lead-time is calculated from, what approvals are required and what the stated delivery date is a milestone for? Please input the requested date into the enquiry and then we will get project specific confirmation from BJY prior to putting the production order into place.

FAQ

Can BJY Help with Preform Design?

We also provide bottle and preform design service. Please send us your proposed drawing, sample or design request and we will be happy to review for you the areas of your interest.

Can Mold Dimensions Be Adapted to Our Equipment?

We can make mold dimensions and runner designs to match our customer’s equipment. Please send us the required information and we will confirm the proposed design for you.

Can We Start from an Existing Sample?

An existing sample can serve as the starting point for reverse engineering. The resulting 2D/3D drawings should be confirmed before ordering and manufacturing begin. Ask BJY to confirm the scope and drawing requirements for your sample.