Understanding Draft Angles in Thermoforming

When it comes to successfully designing and producing a plastic part or product through thermoforming, there are a wide variety of factors to consider. One of the most important factors that can be overlooked is a draft angle. Our thermoforming company in North Carolina is looking at what draft angles are, why they're important, and how your mold type can affect them.

What Are Draft Angles in Thermoforming?

A draft angle in thermoforming is the angle of any taper to vertical sidewalls. A draft angle of zero degrees would mean a perfectly straight sidewall with no taper. For example, when designing the trunk tub for a car's trunk, you would need to determine the draft angles of the walls of the mold to get the depth and shape you need.

When designing for heavy-gauge vacuum forming, it's nearly impossible to achieve a tool with perfectly vertical sidewalls and zero-degree angles.  As the plastic is heated and stretched to fit the tooling, it forms into or over the shape, depending on whether a male or female mold is used. Once the plastic is formed, it is cooled to hold its shape, but as it cools, the plastic shrinks and tightens against the mold. Draft angles are necessary to ensure the formed part is released from the mold properly and without damage.

Draft Angles in Male and Female Molds

The type of mold you're using also determines the minimum draft angles necessary to successfully shape and form your products.

Male Thermoforming Molds

A thermoforming mold is considered "male" if the design of the mold extends upward from the clamp frame and the plastic is shaped over the mold. In order for the plastic to release from the protrusions in the mold, the minimum draft angle is around four to five degrees, so slightly tapered from vertical. If the part is extremely deep, such as with a bathtub or a car's trunk tub, the draft angle will need to be larger.

Female Thermoforming Molds

A thermoforming mold is considered "female" if the design of the mold is below the clamp frame and the plastic has to be pressed down into the shape. While they are a bit more expensive than male molds, female thermoforming molds can have sharper corners and lower minimum draft angles. A one to two-degree draft angle is generally the minimum to get the best results. However, any parts that have molded-in textures often require a larger draft angle to ensure successful removal from the mold.

Get a Free Quote for Thermoforming Today

If you need plastic parts or products, reach out to our thermoforming company in North Carolina today. We have an experienced team of designers, engineers, and manufacturing specialists who will ensure you get the high-quality, durable plastics you need with a fast lead time and a low per-unit price. Our company supplies plastics across the Southeast and Mid-Atlantic states including North CarolinaSouth CarolinaPennsylvaniaMaryland,  TennesseeGeorgia, and Virginia. Call us at  919-404-2080 or fill out the contact form to get started.

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