As we are entering the depths of the festive season, we felt it appropriate to have a blogpost or two with a seasonal theme. The principles of this post however, will be applicable any time of the year.
We are going to be using our injection moulding kit to make some Christmas-themed tree decorations and fridge magnets. For those of you unfamiliar with the kit, it can be used to teach the basic principles of injection moulding, but at a very low cost compared to commercial equipment. You create a 2D mould by either lasercutting a material e.g MDF or acrylic, or by bending a thin aluminium strip. Once this is sandwiched in between the two large plates, you can inject it with a thermoplastic – in our case, coloured hot-melt glue. This method means that basic injection moulding is achievable by all, and on a low-budget.
Without further ado let’s get into our project! First of all, we need to think about what is is we are trying to make. As it is nearing Christmas, we wanted to go for something festive. We decided on making tree decorations/ fridge magnets. The principles for our moulds will be pretty much identical.
To start with, we are going to make a Christmas tree-shaped mould, using the aluminium strip. We measured our maximum working dimensions, and planned a tree-shape within that range.
We then set to work creating our mould. It’s a good idea to turn on your glue gun now, if you can keep it in a safe place, so that it is ready to use when you’ve finished your mould. We need to bend the aluminium strip into our required shape. This can be made much more difficult than it needs to be. The main thing to remember, is to start near the end of your strip, so you aren’t trying to bend it in on itself too much. We modelled our shape using ‘sheet metal’ mode in Fusion 360. The great thing with this, is that we can unfold our model, and create a template. But you could easily print out a template and mark out where you need to bend the metal.
Once you have your mould, you need to place it inside the outer case. Don’t forget to place it so that the injection hole is within your desired shape. It also helps to slightly grease the mould, to allow the glue to separate from the case/mould. We’ve placed a small magnet inside the mould, and held it in place with another magnet on the outside.
*Note that we have made a clear acrylic top plate, to make it easier to see whats happening inside.*
Once you’ve screwed the top plate of the mould on, double check that there aren’t any gaps, and that the case isn’t bowing. You may find it easier to place the ‘wings’ of the mould plates the same way, so when you screw them together, they hold the wire frame tighter. This is especially useful if you can’t quite get your mould to sit flat.
The other method for mould making, is to laser cut a piece to go in between the plates, to replace the bent wire. This time, we’ll make a snowflake tree decoration.
Once designed and cut, follow the same steps as before, to create your object.
You can then either glue some string to the decoration, of pierce a hole in the top, and pass some thread/wire through.
And there you have it, your very own DIY injection moulded Christmas decorations.