Vacuum Forming - Types of Molds

Types of Molds

Wood patterns are generally the first stage in vacuum forming. They are relatively inexpensive and allow the customer to makes changes to their design easily. The number of samples that one is able to get from a wood pattern depends on the size of the part and the thickness of the material. Typically, wood patterns are used to gauge general functionality of both the part and the thickness of the material. Once the specifications of the part have been met, the wood pattern is then used to create a ceramic composite mold, or cast aluminum mold for regular production.

Cast aluminium molds are cast at a foundry and typically have temperature control lines running through them. This helps to set the heat of the plastic being formed as well as speed up the fabrication process. Aluminium molds can be male or female in nature, and can also be used in pressure forming applications. The main drawback with this type of mold is cost.

Machined aluminium molds are like cast aluminium, but are cut out of a solid block of aluminium using a CNC machine and a CAD program. Typically, machined aluminium is used for shallow draw parts out of thin gauge material. Applications may include packaging and trays. Cost is a significant factor with this type of tooling.

Composite molds are a lower cost alternative to cast or machined aluminium molds. Composite molds are typically made from filled resins that start as a liquid and harden with time. Depending on the application, composite molds can last a very long time and produce high quality parts. Within the category of composite molds, the subset of ceramic molds has consistently proven to be the most durable. While not temperature controlled, these molds can run nearly as fast as cast or machined aluminium, yet at a substantially lower price point.