WILD CARD WEEK

Objectives

Design and produce something with a digital process (incorporating computer-aided design and manufacturing) not covered in another assignment, documenting the requirements that your assignment meets, and including everything necessary to reproduce it.

Vaccum Forming

Vacuum forming is a manufacturing technique used to shape plastic sheets. In this process, a plastic sheet is heated until it becomes flexible, then a vacuum is applied to pull the sheet tightly over a mold. As the plastic cools, it hardens and takes on the shape of the mold. The formed plastic part is then trimmed to remove excess material and achieve the final product dimensions.

Image

Design Rules

• Material Flow and Webbing
Sharp corners are to be avoided as this will hinder the flow of material and maximise the chance of webbing.
• Draft/Taper
These terms relate to the amount of angle on a vertical face to allow the parts to be removed from the tool.
• Draw Ratio/Required material thickness
Draw ratio refers to the height of the part to be formed compared to the footprint of the part.
• Pockets and Ribs
Any pockets or space between ribs must conform to a ratio. Depth of pocket or space between ribs cannot be greater than its width and preferably 75% of the pocket depth.
• Designing for Undercuts
Undercuts are design features in which a portion of the mold protrudes into the plastic, preventing its direct removal from the mold.
• Utilizing Radii and Chamfers
One of the most critical aspects is to avoid manufacturing parts with sharp corners. These angles can lead to uneven material distribution, increasing a part’s vulnerability and reducing its overall strength.
• Staying Within Tolerances
Measurement tolerances directly affect a part’s functionality, performance, and its suitability for its intended application.

References

Vacuum Forming – A Design Guide 6 Proven Vacuum Forming Design Guidelines

Designing petals

I needed to make petals for my final project. So I tried to make petals using vaccum forming. Inorder to make, first I made a positive mold. The mold was designed in KiCad and 3D printed in BambuLab A1. I wanted to close the petals completely and was planning to have six petals. So I started by drawing a 5 cm circle and used spline tool to shape petals.

I revolved the spline around the perpendicular line from the centre of the circle and added planes at 60 deg apart each other. The next step was to split the body through the planes to get the required shape.

Then I added holes to place the petals in a base and added joints to attach petals to the body. Using rectangular pattern, I got six copies of the same.

3D Printing and lasercutting the parts

A single leaf was 3D printed first.

Five petals were printed after. As I needed a base to place the petals, an acrylic sheet was cut with holes to attach the base of the petals.

Mistake :-My instructor told me that I needed to add holes for vaccuming, which I didn't add. So I had to add holes around the petals. It was supposed to add right beside the 3d petals in a uniform way. But I placed it in a random order. To add holes, I cut the outerpart of acrylic in a cardboard. The cardboard is then placed as a reference and made the holes in acrylic sheet.I used M5 nuts to hold petals in place.

Mayku Form Box

Initial Setup

• First we need to plug form box into the mains.
• Then plug the vaccum cleaners's power cable into the back of the Formbox and switch vacum cleaner on.
• Connect the vaccum cleaner's hose into the vacum tube of formbox.
• Power on the formbox

Setting temperature and time

• Each type of sheet comes with a recommended temperature setting (numbered 1–6) and heating time (in minutes and seconds). Find these values on the sheet’s packaging or instruction manual. Here I used form sheet to shape my petals.

• Locate the timer dial (right dial). Turn it to the recommended heating time. This timer controls how long the sheet will be heated before forming.
(Make sure to set timer dial first)
• Locate the temperature dial (left dial). Turn the dial to the recommended temperature number. The heater light will begin to flash orange, indicating it is heating up.
• When the FormBox reaches the set temperature, the heater light will turn green. Do not insert the sheet until the light is green.

For my material the temperature was written as 5 and heating time in the range 2:00 - 2:20

Load and Heat form Sheet

• Unclamp the Tray Handles
• Peel off the protective film from the sheet
• Position the sheet on the bottom tray.
• Lower the top tray onto the bottom tray. Firmly clamp the tray handles to secure the sheet in place.

• Raise the clamped trays upwards toward the heater until they click into place.
• Press the timer start button. The heater light will flash orange, and a slow ticking sound will begin.
• As it heats, the sheet will become soft and flexible, ready for forming.

Place the Mold

• Place the mold in the center of the vacuum bed.
• Make sure it is not too close to the edges—leave at least 1–2 cm of space all around the mold.
• Secure the Mold (if needed)

Ready for Forming

• Once the sheet has softened and is flexible (after heating), pull the tray down over the mold, and the vacuum will activate automatically to form the sheet around it.

• After vacuum forming, leave the sheet in place for a minute or two to cool and harden.
• Once cooled, unclamp the tray handles and carefully open the tray to release the formed sheet. Gently lift the formed plastic sheet off the mold.
• Using a pair of scissors or a craft knife, cut out the desired shapes from the formed sheet.

Mistakes:-The holes weren't proper. So the material didn't completely covered the mold. The drag angles were not considered during designing. So the mold couldn't be removed out of the form easily.

Files

Files