Getting the most out of 3D printing in the classroom
3D printing is one of the greatest things to happen to Design and Technology. It’s literally changed how we make things, inspiring a generation. Even with all the amazing gadgets that young adults see every day, 3D printers just have a bit of magic about them. They create possibilities, and that is captivating.
Just teaching 3D print technology isn’t going to help students pass their GCSE.
As you know, there’s a whole range of manufacturing processes to learn. The reality is 3D printing won’t take them over, not for a long time yet. That doesn’t mean you can’t use your printers to make learning about industry more fun. In fact the opposite is true.
Vacuum forming moulds.
As they go, vacuum forming is a straightforward production process. Moulds can be made from fast cast resin, or CNC machined into wood or foamboard. Yet, the casting is messy and inaccurate, and the CNC approach is accurate but wasteful.
3D printed tooling benefits:
· Low cost
· Less wasteful (sustainable production option)
FDM mouldings remove the need to drill holes because of the inherent porosity of the process. On more expensive machines like the Projet Series, the detail is much finer. They are great for organic and curvy moulds, but will need vents within the design.
Watch the process of mould making for vacuum forming.
Our top tips for making vacuum form moulds:
1. ABS and HIPS work well together. ABS has a higher melt point than HIPS (140-190 °C vs. 120-140°C), but they both soften at around the same temperature. For continuous use, consider Nylon as alternative.
2. For ease of removal 5° draft angle is ideal, with a minimum of 1°. Avoid undercuts unless the sheet is thin, and you have enough space to remove the mould
3. The more draft, the less likely webbing will occur
Companies like Candy Mechanics use 3D print and vacuum forming to make personalised lollies. Their technique uses a handheld 3D scanner along with a 3D printer to produce a male mould. This is laid on the bed of a vacuum former, and moulded with food grade PVC. This material works great with ABS, as it has a glass transition temperature of 80°C.
We love this as a project. It combines product design with food preparation and nutrition. Giving a real-world approach to business and technology.
Building on food idea, you can also use 3D printing and silicone to make low cost moulds.
There isn't much silicone moulding going on in the UK (unless you live in Ross-on-Wye). But things have started to change, with the rise of personalisation and the micro business revolution.
French bakers, Babines are riding the wave of individualism, providing customised sweets for brands. Their process takes a simple design, and then print the male form of the mould. In the video they use a milled outer form, but you could print that too. They pour silicone is into a mould, and leave it to set. Once finished, the mould is ready to use.
Making it with Pewter.
Machining out rubber is tricky and MDF fumes, but there is another way to create CAD designed moulds.
PLA can be used as a base mould material. It just requires the design to be inverted, so that the form becomes the cavity. There are a few other considerations to take:
1. When you make your mould, you’ll need to form a funnel to get the pewter into your mould
2. Once poured, you’ll need to quench the mould in a cold water bath. The glass transition of PLA is 60-70°C, and it has a melting temperature of 173-178°C. If not cooled, molten pewter will destroy your form. On the upside, the heat will smooth off any rough edges on your moulding
3. Once cooled, heat off the PLA outer shell in a convection oven. As pewter has a high melting point (235°C) the shell can be easily removed
Our price on pewter is the most competitive in the market. It’s non-toxic and has excellent casting properties from £24.99 per 1kg.
Take a look at the whole process in more detail:
Big project ideas. For less.
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