Sand casting using a mould
Slide 42
The final method to obtain a blank for this part is casting with a mould. In this case the mould is permanent and is made of steel.
To obtain the mould, we start as always with the base model from which we have removed the volumes which will be machined.
It is necessary to make a rough mould, illustrated in green, and the mould joint, which is in orange The software then divides in two parts the rough mould; one part is called the fixed section and the other part is called the mobile section of the mould.
Slide 43
Here are the two sections of the mould.
The software has extracted the reference model from the left section of the mould, and has carried out a volume subtraction to obtain the cavity of the part.
Slide 44
Once the cavity is formed in the mould, it is necessary to design with CAD the elements required for casting, which in our case are:
The core,
The filling point,
The feeder heads.
Slide 45
Once all these elements have been prepared, the software can do a digital simulation of casting by filling the cavity. We obtain the part illustrated in grey.
Slide 46
To verify the design of the mould it is possible to use rapid prototyping to make a ceramic mould based on the digital model.
We can see the digital mould and the corresponding ceramic mould.
In this case, the prototyping machine works layer by layer, applying glue in the necessary places, and then ceramic, and so on, for each layer.
The ceramic only fixes in places where there is glue, all the other layers then break away and we obtain the required object.
Slide 47
We are now going to carry out the casting step. The two sections of the mould are clamped together with mould clamps.
Slide 49
Once the casting is finished, it is possible to analyse the results obtained and check the quality of the cast part.
At this stage it is possible to modify the digital model before moving on to the next step: machining the steel mould.
Slide 50
The mould can be machined in steel. With the same method as we used for the sand casting, we use the 3D CAM programme.
This photo shows the completion of the rough mould in simulation.
The second photo is at the end of simulated machining. The third photo shows the mould being machined, and the fourth photo is the finished mould.
