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→Health and Safety with Vacuum Forming
=== Undercuts ===
=== Undercuts ===
Similarly to the reason we apply draft angles, we avoid undercuts to prevent the risk of our mold getting stuck. A good way to avoid them is to ask yourself if your 3D part needs supports. If it does, then chances are that your mold will get stuck in your vacuum formed part.
Similarly to the reason we apply draft angles, we avoid undercuts to prevent the risk of our mold getting stuck. A good way to avoid them is to ask yourself if your 3D part needs supports. If it does, then chances are that your mold will get stuck in your vacuum formed part.
[[File:Undercuts.png|center|thumb|577x577px]]
[[File:Undercuts.png|center|thumb|577x577px|Comparison between annon-removable undercut (left) and a removable undercut (right)]]
=== Possible Depths ===
=== Possible Depths ===
A plastic sheet only has a certain amount of material available to form a mold. There is a limit to the amount a material is capable to draw. There are formulas and guidelines available to determine that limit. When it comes to cavities, the maximum depth should not exceed 75% of the opening.
A plastic sheet only has a certain amount of material available to form a mold. There is a limit to the amount a material is capable to draw. There are formulas and guidelines available to determine that limit. When it comes to cavities, the maximum depth should not exceed 75% of the opening.
[[File:Depth.png|center|thumb|456x456px]]
[[File:Depth.png|center|thumb|456x456px|Demonstration of reachable depths]]
=== Draw Ratio ===
=== Draw Ratio ===
=== Edges / Fillets ===
=== Edges / Fillets ===
Whenever you create a part for vacuum forming, you want to avoid sharp edges or sharp angles as much as possible. The thicker your plastic is, the less capable it will be to take the shape of those sharp corners. The thinner the material is, the more susceptible it is to overstretching.
Whenever you create a part for vacuum forming, you want to avoid sharp edges or sharp angles as much as possible. The thicker your plastic is, the less capable it will be to take the shape of those sharp corners. The thinner the material is, the more susceptible it is to overstretching.
[[File:Edges Fillets (1).png|alt=|center|thumb|360x360px]]
[[File:Edges Fillets (1).png|alt=|center|thumb|360x360px|Example of smoothing out corners for easier part forming]]
=== Air Holes ===
=== Air Holes ===
== Health and Safety with Vacuum Forming ==
== Health and Safety with Vacuum Forming ==
Vacuum forming is a generally safe machine that takes little effort to manufacture parts with great quality. Although, there still are safety aspects to take into consideration.
Vacuum forming is a generally safe machine that takes little effort to manufacture parts with great quality. Although, there still are safety aspects to take into consideration. When you encounter a problem with the machine, it is important to alert the staff about it and DO NOT attempt to fix it yourself. Reparations and changes to the machine should only be made by qualified personnel.
=== Burns ===
Evidently, the vacuum form machine uses heat reaching up to 300°C to soften the plastic. Consequently, some parts of the machine can get very very hot. It is important to know which those are and keep body parts clear of these area. The plastic part will also be very hot after forming. You should let it cool down before attempting to handle it. If you must handle the part immediately after forming, wear the proper PPE such as heat protective gloves. To test to see if the part is still hot, approach it gently with the back of your hand. If you can feel the heat without touching it, it is probably too hot to handle. If you cannot feel any heat from a distance, try and get closer until you can touch it rapidly without feeling excessive heat. From there it should be safe to touch the part without getting burned instantly and gauge if you can handle it or not.
=== Toxic Fumes ===
It is important to keep in mind that melting a plastic emits toxic fumes. Although a vacuum form machine doesn't completely melt plastics, it does bring it past it's glass transition temperature, where polymer chains are allowed to move some encounter thermal decomposition. During thermal decomposition, polymers breakdown into hazardous plastic fumes, fatty acids, and the original manufacturing compounds.<ref>[https://www.sentryair.com/plastic-fumes.htm#:~:text=During%20thermal%20decomposition%2C%20polymers%20breakdown,fires%20in%20a%20burning%20building.]</ref> Material choice is important not only for your project, but also the safety of the people working int the same space. Have your material approved by staff before using it. '''Do not leave heaters unattended and do not overheat plastic sheets!''' Doing so will increase the risk of releasing toxic fume.
=== Trapping ===
There is a risk of trapping when operating the vacuum form machine. Use caution when using the clamp frame to ensure fingers or hands will not get trapped. This is a single person operating machine. Use caution when someone else is around.