What is webbing?
When plastic folds over itself in thermoforming, it's called "overdraw" or "overstretching." This happens when the plastic sheet is stretched too much during the forming process, causing it to create folds or wrinkles.
How does it occur?
Webbing occurs in areas of deep draws or sharp corners in the part. It happens when the plastic sheet is forced to conform to the tool shape, leading to excessive stretching and the formation of folds or wrinkles. It's considered a defect because it can weaken the plastic and make it look uneven.
How can I avoid it?
Webbing when using the FormBox is either a tool issue or a user error.
Tool issue
Wide parts are easier to form than tall ones. This means you should strive to create tools that are wider than they are tall – or use generous draft angles to compensate.
Sharp corners
Sharp vertical corners are more likely to cause a plastic sheet to web and tear during the forming process. To avoid this and improve final part quality, ensure that all of a tool’s corners and edges are rounded.
User error
The tray was pulled down too quickly or the sheet was too hot when you formed.
When pulling your trays down to the base of the FormBox, you only need to apply enough pressure to make the silicon seals airtight. This is roughly about as much pressure as you would use to close a tupperware lid. A quick action to remove the trays from the heater unit followed by a smooth downward motion to lay the plastic over your template will create the best forms.
How do I form without getting webbing?
How much pressure should I apply when lowering the trays of my FormBox?
How do know when my sheet is ready?
Overheating material
The sheet crystallizes (goes white) when overheated, look for the point where the sheets starts to bow.
Removing the tool from the formed sheet
Apply PTFE before forming for end parts (DO NOT USE if casting edibles)
- Use PTFE for easy de-moulding; cover all surfaces of the tool that will touch the plastic sheeting with PTFE Spray
- Wipe surfaces clean so that it is dry to the touch
- We recommend doing 4 coats
- Ready to form
Removing the tool from the formed sheet
Apply PTFE before forming for end parts (DO NOT USE if casting edibles)
- To make demolding easier, use PTFE spray. Cover all surfaces of the tool that will touch the plastic sheeting with PTFE spray.
- Wipe surfaces clean so that they are dry to the touch.
- We recommend applying 4 coats for best results.
- Once done, you are ready to form!
Tips for demolding
Undercuts can appear from a degrading mold where the sharp edge degrades. Here are some tips for difficult tool removals:
- Safe removal. On a soft sponge surface, press down in the center of the formed object, this evenly applies pressure all around the edge and the piece should pop out.
- Riskier removal. On a hard surface, with one hand push down on the center of the printed part, with the other hand pull the material and work your way round in a circular motion.
- For tough thick material. Cut an offset around the part less than 10mm from the edge. The closer proximity to the edge enables more malleability of the wall, thus air intake and subsequent de-mold.
Note: Do not hit the part against a hard object or pierce the skin unless you want to damage your master mold.
Can you UV Print onto materials before forming in the FormBox?
The key is to use ink specifically designed for thermoforming that is solvent-based and adheres to plastic, preventing the ink from breaking during the heating and stretching process. The most common printing method for this is inkjet printing. Some companies have also started using UV inkjet printers.
We haven’t tested inkjet printing yet, only UV printing, so we are unable to advise on the process at the moment. We recommend that customers outsource to a professional printing company that uses inks and printing methods designed for thermoforming to ensure the best results.
Can you spray paint onto materials?
Mayku Form Sheets are durable and lightweight, perfect for enhancing your DIY projects or product prototyping. You can easily spray or paint them in any color you like!
Here are a few tips for the best results:
- Most spray paints will work fine.
- Lightly sand the surface and apply an all-purpose or plastic primer first.
- After priming, use your regular spray paint.
Acrylic-based paint is more flexible and forgiving, while enamel paints are harder-wearing but less flexible.
Can you draw or write directly onto the Mayku sheets?
Mayku Form Sheets are easy to draw and write on with a marker pen, like a Sharpie, both before and after forming. This makes them perfect for customizing your projects with ease.