3D printing packaging containers and bottles is still impractical and costly, but 3D printing the molds used to create the plastic containers is proving to be a viable alternative to traditional prototyping methods.

Blow molding is the process in which a small amount of molten plastic is inserted into a mold and then compressed to the sides of the mold with a quick burst of high pressure air. This causes the plastic to form a thin layer, evenly distributed along the walls of the mold.

3D model for 3D printed blow moldTraditionally, blow molding is used for products like water bottles or food containers using metal molds that are machined into the desired shape. The cost of producing these molds can be extremely cost prohibitive, if you’re trying to prototype your bottle, so many manufacturers simply skip that step. While rapid prototyping has been a viable tool for a lot of manufacturers, it is only useful when the 3D printed prototype can easily simulate the look and feel of the product being manufactured. But many products that are created using blow molding cannot have their properties and appearances easily simulated with existing 3D printing materials.

Stratasys has already talked about using 3D printed molds to replace traditionally created metal molds for small scale injection mold manufacturing; however, they’ve now adapted that process to use a polyjet 3D printer to fabricate molds for use in blow molding for rapid prototyping or small scale production.

As an example, Plasel Plastics recently had a customer that needed to make sure a new package design would be able to fit into their automated conveying system. Plasel used a Stratasys polyjet 3D printer to prototype the mold and create a run of 100 packages for testing. Had they created the molds with traditional manufacturing techniques using a CNC machine or an aluminum mold the process would have taken about twenty days with a cost of $5,000. In contrast, the polyjet mold only took two days and only cost $280.

3D printing is changing the way that we manufacturer and design the products that we use daily. You simply can’t look at those numbers and believe differently. And, while current polyjet printed molds won’t last as long as their machined counterparts, if you consider how quickly new 3D printing materials are being created, it’s clear that that isn’t always going to be the case.

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