Troubleshooting Tips for Twin Sheet Thermoforming

Twin sheet thermoforming is a complicated process used to manufacture hollow or double-walled plastic parts and components. It's most often used to produce air ducts, vending machine chutes, bed liners, and surface panels in an efficient and affordable manner. However, if it's not done properly, errors can lead to both cosmetic and structural problems that could ruin a project. To get the best results, our thermoforming company in North Carolina is sharing troubleshooting tips for twin sheet thermoforming.

What Is Twin Sheet Thermoforming?

Twin sheet thermoforming is performed by heating up two sheets of plastic simultaneously until they are malleable. Then, they are both placed on molds and clamped into place while a vacuum draws both sheets tightly against their molds to get a precise shape. When complete, the two pieces are compressed and thermally joined without having to use adhesives.

This method is often preferable to injection molding and other types of plastic manufacturing because the tooling is less expensive and easier to fabricate, leading to lower prices and faster lead times.

Troubleshooting Twin Sheet Thermoforming

Now that you know what twin sheet thermoforming is and why it's used, let's look at how to avoid common errors and problems that could weaken the product.

Aligning the Mold

While both molds used may have different shapes, angles, and protrusions in them to get the best result, they must be perfectly identical where the press points are located. The press points are where the two sheets join, so it's absolutely essential that they are in proper alignment. Misalignment can lead to the sheets not properly joining, causing structural weaknesses in the finished result.

Adjusting the Sheet Temperature

The temperature of the sheet during the molding and forming process also determines its success. If the sheet is too hot, you may get puckered areas extending up out of the plastic sheet on the side touching the mold, or you may also see webbing on the plastic. While these are more cosmetic flaws, in severe cases both webbing and puckering may be signs of weakened areas in the plastic. On the other hand, the plastic being too cold can also cause problems, including stretch marks and poor part detail.

Proper maintenance of the equipment will ensure that the plastic heats evenly, though you may need to increase or reduce sheet temperature to fix any flaws before continuing the manufacturing process.

Vent Placement

When the two sheets are joined, hot air is trapped between them, which could cause the cylinder or panel to collapse as it cools. To keep this from happening, vents are placed along the mold to facilitate cool air circulating.

If the vents aren't placed properly, there may still be issues with sagging or collapsing, which would ruin the components being produced. However, vent holes must also be positioned in a way so that the marks they leave in the plastic are not visible. Often, we will ensure that the holes are placed on the interior side of the panel so they are invisible. This gives us the ability to place vents in the tooling exactly where they are needed.

Contact Us for Twin Sheet Thermoforming

At Advanced Plastiform, Inc., we offer both thermoforming and injection molding services and guarantee fast lead times and low per-unit prices. We work with industries across the Mid-Atlantic and Southeast, including North Carolina, South Carolina, Pennsylvania, Maryland,   Tennessee, Georgia, and Virginia. To learn more about our services or get a free quote, reach out to us today.