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A Guide to Tooling and Mold Design for Manufacturing

tooling and mold design

Tooling is the backbone of plastic injection molding. Without a proper tool design, your plastic part would never scale up properly and a quality tool design can save you enormous amounts of time and money during production. Before you contact a toolmaker, here are a few facts about tooling you should keep in mind.


What is tooling?

Tooling, also known as a “mold”, refers to the negative cavity space where molten plastic resin is injected to create a part. The foundation of the plastic injection molding process, proper tooling is required to create both high quantities and quality of parts. Since the design and construction of a tool is so complex, fabrication requires both capital investment and enough lead time to create an effective tool.


What is prototype tooling?

 The tooling design process starts out in the prototype phase. Prototype tools are created through 3D printing, cast urethane, and machining. These low volume prototypes are used to troubleshoot, develop, and validate the tooling design during pilot production. While this may seem like an unnecessary expenditure, cutting down on errors in the manufacturing and assembly process early can significantly decrease time and cost later.


How to design and make a tool

Proper tooling design and choices need to take into consideration a large variety of factors such as complexity, lifetime, application, and potential production volume of the tool. Choosing which tooling to invest in is the hardest part of the tooling process. If the part is going straight into high volume contract manufacturing, then it will be most cost-beneficial to invest directly into expensive production tooling for the long term. In other cases, such as low volume manufacturing, it may be more beneficial to stick with prototype tooling until production increases significantly.

Toolmakers can provide a lot of assistance with the tool design process because they are well-versed in the techniques of fabricating and designing the tooling. They can run mold flow analyses to optimize the tooling design and they can choose the best locations for parting lines, gate, and ejection locations. A quality product design engineer will work closely with toolmakers to ensure that the optimal tool is fabricated for your application.

After collaborating with the toolmakers on the design, the part is ready and approved for the T1 sampling stage. They will build the first tool with a 2-16-week lead time dependent on design considerations. T1 sampling demonstrates that the tooling functions properly and produces ideal parts. After the T1 sampling is accepted, then any necessary modifications and aesthetic mold texturing can begin. These additional modifications can take 1-2 weeks to complete. The modified molds, referred to as T2 samples, are sent for approval of texture and appearance. If they are approved, the T2 samples are released to the contract manufacturer.

Once with the manufacturer, T2 samples are placed into the production line where process development and qualification of the parts is performed. The tooling undergoes a series of molding studies that help outline the optimal conditions and characteristics for creating parts using that tool. Design of experiment trials are run to isolate process inputs and corresponding impacts on characteristics. All this initial testing helps the molder validate an ideal processing window that produces parts within specification.

After initial process development, qualifications, and validations, the tool will enter a regular production maintenance schedule. The tool is regularly monitored for wear and any other potential issues that could affect part quality or tooling lifetime.

In total the entire process from prototype to production can take months and significant investment to properly complete. Therefore, it is vital to design for manufacturing throughout the product development process. A product design that can be easily prototyped through machining or 3d printing may not easily translate to tooling design for high volume production. We recommend partnering with a product development company that is intimately familiar with the tooling design and manufacturing process and incorporates that knowledge into designing your product from the start.


Basic features of a tool

  • Cavity half - The side of the tool that does not move. It is typically attached to the side of the molding machine.
  • Core half - The side of the tool that opens and closes with the mold machine against the cavity half. It will open when the part is being removed from the tool.
  • Cooling Lines - Channels that allow coolant to flow throughout the tool and control the cooling of the plastic part.
  • Ejector System - Pins on the core half of the tool help to push the cooled part out of the tool after it is molded.
  • Runner - A flow path for the plastic resin that will allow the press to inject material directly into the part cavity.
  • Side Actions - Moving pieces within the part cavity that can be added to allow for undercuts in the part.


About Synectic Product Development: Synectic Product Development is an ISO 13485 compliant, full-scale product development company. Vertically integrated within the Mack Group, our capabilities allow us to take your design from concept all the way to production. With over 40 years of experience in design, development, and manufacturing, we strive for ingenuity, cost-effectiveness, and aesthetics in our designs.  Learn more about our contract manufacturing services and see how we can help your next project.

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