In the last post, part one, I discussed what sort of changes to the materials and to the electronics that would need to be made if my project were to be put into production. I am writing this not because it is necessary, but because I think that it is important for the project and part 2 is going to show this even more than what part one did. So without further ado, let’s begin.
This is quite an important part that needs considered. In the last post, I narrowed down the material choice to two. Plastic or aluminium. The choices for both were quite compelling. However, one of the main factors that will decide what still needs to be done, is that of how it will be formed. The production run has quite a big say in this too. I stated a figure for units somewhere between 100,000 and 800,000.
This larger number can automatically discount a good few manufacturing processes which would in turn not have been feasible anyway such as rotational moulding.
Manufacture of Light Prism
The manufacture of the light prism can be done in a number of different ways. Essentially it is just a block, but depending on the best method it could easily be hollow or a section of a tube. However, with each different method that it could be made would result in different effects in how it plays with the light. The solid block provides a beautiful glow that appears to come from nowhere. In the earlier prototypes, the plastic was layered up and each layer caught the light and spread it out.
I think that if the light prism was hollow it would have an adverse effect on how the light would look. The best option would be a solid block. But how would that be manufactured? Cast is one of the main options even though it may not look good if it was cast plastic. Injection moulding could be used but because of the size, the cooling time would be quite long. This would not be good for manufacturing times. Probably the best way for manufacturing the block to the right size would be the same as it was made when I bought it. Extruded and then machined into the right size and shape. The edges could then be polished up and it would look quite good. The size of the parts, if machined, could be done to extremely fine tolerances meaning that the overall finish of the product would be excellent.
Glass on the other hand would be completely different. I am going to put my hands up now and say that I am not an expert at all in how glass is cast (formed?) apart from how they make windows with the stuff. I know that the method that is used to make windows would definitely not be the way to make the block. Glass blowing is probably closer to the mark but I don’t think it would. The problem with glass is that it cannot really be machined into shape when it has been formed due to the crystal structure. I think because of this, no matter which material was used for the main body, plastic (most likely perspex) would be the best option to make the light prism mainly because it is much more usable as a material for mass production in this sort of thing. It isn’t like windows where it is a large sheet, it is a block that would need extrusions, holes and other details.
Manufacture of Main Body
As per the light prism there are numerous ways of manufacturing the main body. With options including injection moulding, casting, machining etc, there is an almost bottomless pit in terms of manufacturing options. Irrespective of the manufacturing options, I think that whatever material is used, the manufacturing process should be the same for both, or try to be the same for both.
I like the idea of taking a billet of aluminium and machining it to the right size. This is basically what Apple do with their computers, making ‘unibodies’. These are ultimately stronger than their conventional counterparts. This wouldn’t work for plastic though, as it wouldn’t leave as good a finish and the plastic would be more likely to split or crack when trying to get a supremely smooth polished finish.
Injection moulding is probably a mistake too. For a start, injection moulding metal for the purposes of the product would probably look terrible, if it is at all possible. The injection moulding of the plastic, whilst already a very common method, leaves flash lines where the material starts to seep into the gaps in the mould, it would also have sprue pin marks. Whilst this option is already very common in terms of mass production I do not think that it is right for the product. I don’t really want it to have the mass produced look. A quality product should not have a sub par method of manufacturing it.
I suppose extrusion could be used, but the internal method would have to be changed slightly in order for the parts to fit together better and for there to be no sign of how it was made on the raised portions of the main body. I can’t quite explain it, but the extrusion would have to change part way through for it to work. Also there would be an obvious join line in between the main sides and the flat top surface. I could draw a diagram but I don’t think I would be able to show it properly.
This takes me on to the plethora of options regarding casting and forging. There are a number of options that could be used. But thinking about it none of these would be as good.
In an ideal world, and with the advice of engineers, I could make the product the same way no matter what material was used. But the fact of the matter is, I don’ think that it would be possible at all. For the aluminium bodied ones, machining would be used. This would give an excellent finish and an extremely high level of detail that would make the product look and feel premium. For the plastic, despite my reservations about it, it would have to be injection moulding. As for draft angles, I would want to try and reduce them as much as possible. One of the main design features of my product is that the sides are straight and parallel. If this means that the mould has to be split into more parts then so be it. I don’t want draft angles to destroy the look that I have created just to make it easier to manufacture.
I suppose that is a downfall of what I am trying to achieve. I don’t want to make any compromises for my project, not now and not even hypothetically in the future if it was to be mass produced. I don’t think that compromising is what people should do when they know it has to be well made, try and make an emotional connection with the user (especially in my case when it disrupts something as valuable as sleep). Making it the way that I want it to be is selfish I know and not really taking into the considerations that engineers have. But if you don’t push yourself, or push the methods that people currently use, then I don’t think there is any point in trying to be the best you can.
Joining of Components
Main Body Parts
The joining of components is a very important aspect to consider and in a sense needs to have different approaches for different materials.
I will first look at the joining options if the product was manufactured from plastic, i.e. the body is plastic and the light prism is plastic. Currently, due to time constraints and sourcing problems, the light prism is not attached the way that I would have wanted it to have been joined. It has been stuck with a very strong tape to the body pieces and not joined in the way that I originally wanted it to be joined (see sketch below). If made from plastic, the plastic piece could easily be done in a similar sort of way, in fact it could even be a hollow extruded square tube. On either end of the tube would be latching points, and on the main body and lower part of the body, there would be corresponding latching points. This would be a relatively permanent way of fixing it. Meaning that the user would be unable to access the internals of the product. Known as a snap fit (just remembered the name half way through describing it) it would mean that it could not be tampered with. I like this sort of approach. I don’t think that the user should need to access the internals that easily. Especially for that sort of age group. My general philosophy for the whole project is that I wanted it to just work. No frivolous controls or things that the user has to worry about. In the end, the joining surfaces would be quite good. There would be minimal overhangs or lips on the joining pieces. But the tolerances would have to be spot on.
That is option number one for joining the plastics together. The second option for the plastics would be some sort of glue. I suppose that this is basically the option that I have already gone with albeit with tape. The glue would almost certainly be permanent. This would mean that not only would the user not be able to access the internals, but if it was sent away for repair, the technician would not be able to access the thing easily without it breaking. This really isn’t a sustainable way of producing something because as soon as it breaks, you would be better off just throwing it away rather than attempting to get it fixed. Part of this has to do with the materials that are used. It tends to be difficult for people to make an emotional connection to something that they know has been mass produced and if when they know it has broken, then that is it, there is no going back.
The connecting of components if the parts were made from aluminium/glass/plastic or any combination of those three would mostly be similar to that of just plastic. The glass makes things a little more complicated due to its material properties and that it is very difficult to machine it after it has been initially formed. There is an option of screws. I wanted to stray away from the option of screws in the project because unless I had got a good few nice looking screws, perhaps pentalobe or hex, it would have looked quite bad. I did toy with the the option of just having a single screw on the whole product. It would be used to tighten a metal ring that would grip onto an extrusion on the top of the light prism meaning that it was gripped on. In this case the bottom part would be affixed in a different manner to the light prism than the main body. This brings me on to the next idea which could be used for either plastic or metal. Extremely tight fitting components.
I know that isn’t the technical name for the method that I am thinking of, but I don’t know what it would be called anyway. Basically the tolerances of the component parts would be so fine that it would be it and no external adhesives or screws would be used to hold the components together. Think of it as a suction fit. The parts are slotted together so tightly that they could only be separated with use of a machine.
So which method do I think would be most appropriate for the product? Of all the methods examined and looking at how I joined the parts together in the final prototype, the best option and the one which would mean easy access for maintenance but discouraging user involvement, would be the screw option with the tightening ring. It is simple yet innovative engineering which I wish I could have implemented in my project. The type of screw on the end would be a nice polished sliver looking pentalobe screw that would be located approximately 10mm below the USB port.
As for how the internals would be joined, it is a relatively different story. I think that I got the method just right for quick and easy assembly of the exterior and interior. If the internal structure is manufactured in the same way and slotted in, then there is no need for there to be any sort of adhesive or screws used. In a sense, it would just work. It would be simpler for the manufacturers, along with quicker and it could easily be assembled by a machine, saving on labour costs and therefore helping keep a healthy profit margin.
How much will it cost? A very common question I suppose. There are a number of factors that will play into this total such as production run, materials, shipping, labour, etc. There is one price point that I would not want to make it more expensive than. That is £100. That may seem like an obvious point as it is aimed at younger people, but be assured, it is something that people may not pay much attention to. Quite a lot of young people don’t buy things for themselves, with expensive electronics increasingly being bought as presents or just because the teenager cannot afford it, it is usually the parent that has to fit the bill.
In a sense, where the product is manufactured can influence the overall cost of the product, but that is normally absorbed into the shipping and labour costs with no other real expenditure apart from local taxes. There should also be a minimum price point. Something low enough that it will encourage people to buy it, but not too low that it will eat into the profit margins. Based on this idea, I think that the minimum price should be just over £50. I suppose that a range of £50 to £100 is a little vague at the moment, but it doesn’t shoehorn the project into any sort of pigeonhole.
I did touch on this part of the process a few posts back when I was talking about the boxes that I had made for my project. Being able to determine how many products can be transported on a pallet can help influence price, availability and, if running a business, profits. I tried to keep box sizes to a minimum. There really is no extra space in the box that I could have stored something in. It mimics the design of the product itself, where it is very tightly packaged. An approach that I think that everyone should pay attention to.
From the previous post where I mentioned this, the dimensions of the box are 320x85x85mm. If the product was loaded on to pallets at half height, which is about 110cm, an estimated 400 boxes would be able to be loaded. That was the calculations thanks to the other post. Deciding to work it out properly, using the image below I have roughly plotted the layout of one layer of the pallet. I believe that it is as efficient as possible in terms of layout.
As you can see, the shaded boxes are the boxes of the projects. And apart from the two sort of stray looking boxes to the right hand side, it is quite efficient. In fact, to help the stability of the pallet, the two ‘stray’ ones could be placed in the middle with the horizontal boxes to either side of ti. That means that no side has relative weak spots in its construction which could mean that the pallet could be built higher than half height in order to stack more boxes on a pallet safely. In fact, as proof that I am writing this as is rather than checking it over at the end (mainly due to the length), the structure of the pallet would be made much more stable when it is wrapped up and ready to be put onto a plane, lorry, etc. But from experience in working in a warehouse with hundreds of pallets processed daily, a well built pallet is always what you must strive for, especially if when done wrong, peoples lives could be put at risk.
I know that I have rambled on for quite a while in this post (and the previous one for that matter) but I think that exploring the manfacturing and other processes that need to be thought about if the product were put into production are important. I wouldn’t have said it was important for other people to think about for their projects, but looking at what sort of designer I want to be considered as, I feel it is important. I probably have gone into much more detail than I should have done, looking at shipping and all that, but I like details. There is something distinctly OCD about all of this, but I tend to juggle multiple things on my mind at one time. Being able to keep track of everything in my head and not writing it down probably had adverse effects on the finish of my project, i.e. there were some parts that could have been done much better, and it would have put me under more pressure at times that what it should have been, again having adverse effects on the outcome but it has all been worth it.
My knowledge of manufacturing processes definitely needs revising. I have been pushing my brain to the limits to try and remember it all without looking it up on the internet. Having this knowledge on tap, is certainly going to aid designing for manufacture in the future. Whether it for an important part, or even just a prototype. In hindsight, this post is longer than it needed to be, but it clearly shows the sort of thinking that I have been constantly going through over the past couple of months when I have been making my project and even before I knew what it was going to look like.
Anyways, my fingers need a rest… and I need a sleep.