9 Steps to Designing, Building, and Storing a Blow Molded


Blow molded parts play a role in almost every aspect of modern life, from hospital equipment to car parts to children’s toys. They are economical, versatile, and built to last.

Blow molding is an elaborate multi-step process that requires collaboration from many different highly-trained professionals. This article briefly explains the 9 steps to designing a blow molded product to help you better understand the process and select a supplier that is right for you.

Research Suppliers

Perhaps the most important step in designing a blow molded product is researching potential suppliers. Choosing the right supplier determines how well the rest of the process goes.

Different suppliers will be able to offer you different services as well as pricing options. While you read the rest of this article, determine where you will need supplier assistance, and be sure the supplier you choose can meet all of your needs.

Determine the Quantity

The quantity of parts you would like to produce determines pricing, turn-around time, and mold design. A larger order generally means a lower price per piece, but also a longer production time. You can shorten production time by designing a mold with multiple cavities that allow multiple parts to be molded at the same time. This kind of mold is more expensive up front, but will save you money in the long run.

Your supplier can help you determine the most economical way to produce the quantity of parts you need.

Plan the Project Concept

Like quantity, the project concept is necessary to get an accurate quote. Your concept could be as simple as an idea or as complex as a fully-rendered 3D CAD model.

Your supplier will work with you to determine the basic parameters, like size, shape, and resin needs.

Design the Part

Once the concept and initial quote are set, it’s time to design your part! A detailed 3D part design is necessary to determine an accurate quote and timeline.

If your company doesn’t have a team that is qualified to design the part, look for a supplier with a dedicated design team to help you.

Design the Mold

This part of the process is highly technical and requires input from both an engineering team and production team. Mold designs must include the necessary details like parting line locations, cooling patterns, in-mold systems, venting locations, and much more.

Build the Mold

A cost of the mold. Keep in mind that a typical mold takes 8 to 10 weeks to build. While you can source your mold from a shop other than your supplier, using one team for the whole process is the most efficient way to build an error-free mold.

Produce the Part

After all that work, your part is finally ready for production! Production includes setup, molding, quality assurance, finishing, and packaging.

Quality assurance is integral to the blow molding process. Sophisticated tools and a highly trained team are necessary to make sure each and every part is manufactured to spec. Things like wall thickness, color, dimensions, and weight all need to be monitored. Work with a supplier who has a QA program in place to identify and correct imperfections.

Deliver the Final Product

Delivery costs can be hard to swallow. Choosing a supplier who can store and drop-ship your product can help trim these costs.

Store the Mold

Once your project is complete, you’ll need to store your mold until next time. Some suppliers offer storage solutions and will even maintain your mold for the life of the product as long as it’s in their possession.

To learn more about blow molding design, check out our Blow Molding Design Guide. When you’re ready to start researching suppliers, here are 11 questions you should ask.