Pewter Casting

Pewter Casting would be a great activity for pupils in Year 8 or 9, which could be taught over 3 lessons. One lesson could be teaching them what it is, and how it is used in industry, and depending on ability of the pupils, in that same lesson, a quick 2D Design drawing could be drawn, and this could go into the next lesson too. The following lesson could be adding final touches to the deisgns in CAD, and then milling them, and those who have a higher ability and finish quickly could then pour their pewter with heavy supervision from either the teacher or a technician, and those who aren't as quick to the mark could pour the following lesson, whilst those who haev already poured theirs could polish it with wet and dry or file it down.

An example of Pewter Cast jewellery.

The use of CNC Routing would be useful to Year 8's and 9's, as it is introducing them to more machinery, and therefore when they have future design projects, they know that this machine is an option. This gains them another skill in the workshop, and is the step before the Laser Cutter, a machine sometimes used at GCSE and A-Level, and heavily in industry, so this gives them the foundation of knowledge they need for the next pieces of knowledge.

Although at first the students would need help on how to make a mould for pewter casting (e.g. how to make the channel down the the shape, or why contours have to be used), it is something which is easy to grasp, and the more well-able students may be able to repeat the process in the future without much difficulty; this is because 2D Design is a package aimed at schools and simplicity, so pupils can understand it.

For students in Year 9 who are considering Design Technology GCSE, this task can provide vital skills needed at the next level, and skills which will then be improved on. Therefore, it is essential they learn about this process or similar processes, to set them up for later qualifications in this subject.

The whole process once the mould is made is very quick. The pewter is heated overa flame (carried out by teacher or technician), and the pupil would pour it down a channel they would have included in the 2D Design, and sanded in a pour-hole. This is down relatively slowly, so when the mould has been filled, the student can stop when it is complete. This is removed with little effort (sometimes by tapping against the edge of the table) and removed. The pupil making this would be wearing gloves during the whole pouring process, and would take the pewter part to cold water and cool it down. the top is snapped off (where the channel and pour-hole was) and any stubs left can be lightly filed off without much difficulty.


After the process is complete, it is essential to make the product look more presentable. This is done by rubbing the product on different grades of Wet and Dry, or using Steel Wool. On my pewter cast product, i used 320 Grade Wet and Dry and moved to Steel Wool. This was because the product was only 2mm thin, so wasn't easy to move over the surface of a wet and dry board. The Steel Wool took a long time to do, but the result was well worth it, as the product has no dents from the MDF chips, and much less scratches and imperfections.

Sand-Cast Aluminium

Sand Casting is a very old method of making products, or parts of products, but is still used in industry today. An example of how it is still used in industry is the Eames Office Chair. Although this chair was designed in the 1950's, it is still made in Germany today, and remains one of the most famous products designed. The arms,back support and legs are all aluminium cast and prepared by hand everyday. The iconic status of this chair has earnt it a £420 price tag, which represents it's design genius, and the fact that this type of Product Design had never been seen before.

It is possible to sand cast small parts and attach them together. Sand casting is done by placing a mould made from jelutong or MDF in the bottom of the Cope (the bottom half of the cast) and dusting with chalk dust. This stops the mould getting stuck to the sand and makes it easier to remove. Sand is sieved over the mould finely at first, and tamped down to compress the sand tightly together, so there are no gaps. After the Cope is about halfway full, a different sieve is used, which is much less fine. Larger pieces of sand come in, but is still compressed in the same way with force. When this is tightly packed, the Cope is turned upside down, and the Drag is placed on top. More chalk dust goes on the base of the mould (now facing the cieling), and fine sand gets sieved over the Drag and compressed. When this is half way, channel plugs are inserted either side of the mould, which will later be the channel for the aluminium to fill the mould. Once these are in tight and been compressed in, the less fine sand is sieved over again and tightly packed in.

Vaccum Forming

Vaccum Forming is a process used in many secondary schools to shape sheets of plastic to a mould made from cheap woods or man-made boards, such as Medium Density Fibreboard. This is often taught in schools, as the plastics used to make vaccum formed parts are cheap and readily available. These plastics include HIPS, PVC, Polyethylene and Polystyrene.

Pupils can easily make a mould using a CNC Router or in schools with a bigger budget, a Laser Cutter. Pupils could make blister type packaging for a keyring (which ties in with my Pewter made part) just to learn how it is done at a younger age, and then when they are progressing towards GCSE, uses for Vaccum Forming in industry can be taught with specific examples.

To new Year 7 pupils who have never seen big machinery before, all the machines in the workshops can look intimidating, but if they learn to use them from the start, their confidence will start to grow and could perhaps gain more interest in the subject. The Vaccum Former is a machine which could be one of these machines taught to get them used to processes used in industry. I think the key to a successful project based on Vaccum Forming with a young class would be to overlook it, and make sure that all the designs made on 2D Design are possible to make on this type of machine. It also should be exciting to them, for example, making something which looks appealing to them, for example, in a heart shape or similar, so they can design different shapes they are interested in on CAD.

For my Vaccum Formed part, i used very thin transparent PVC. this was due to a complex shape and design, so the suction provided by the Vaccum Former wouldn't have been enough to pull the thick material into the gaps in my design. Also, the thick material couldn't reach into the gaps and would overfill them if it did manage to. The part was transparent as it is for blister packaging for my Pewter part, a Cat-shaped keyring, aimed at children. Therefore, if it were packaging, you would need to be able to see it from the outside.

The benefits of Vaccum Forming in industry, is that it is a very quick method, which costs little to run. Products can be manufactured in bulk, where big groups can be made in the space of 30 seconds, just for the plastic to heat, then the suction only lasts 5-10 seconds. The many varieties of plastics which can be used on this machine can be bought very cheap, and can come in many thicknesses, so all designs have a suitable plastic available to be able to use. Also, as it is a plastic based method of manufacture, the parts you can make on this machine come in all sorts of colours and finishes, so therefore it is a suitable method of manufacture for childrens toys.

To make my mould, i made a cat shape in 2D Design, and cut this out in 2mm MDF on the CNC Router. This piece was glued to a square backing piece of MDF which was also only 2mm thick. This was my mould. To vaccum form this, i turned the 2 most central heaters on to medium to high heat (not full as it was only thin plastic). After this had heated up, the mould was placed in the base of the former, and my sheet of plastic was clipped into place above the mould in the vaccum. The heated plates are then dragged over to heat the plastic not far above it. As the plastic needs to be of a soft and bendy consistency to let the process work, i checked the plastic every 10 seconds to check if it was melted enough to pull onto the mould, by pulling the heat away and very lightly poking the plastic to check solidity. When it was ready, the heat is removed, and the mould is pushed up into the plastic and the vaccum is turned on, bringing any air away from around the edges of the mould, so the plastic is drawn in further to the shape of the mould. When the vaccum is turned off after the plastic is drawn in, the plastic sheet can be removed and the product cut out. Then the product is finished.