This page consists of information and decisions that I would make if I was going to mass produce my product. I have thought about methods that can be used, Quality of the product (for example tolerance), cost and many other aspects. Case I made my case using vacuum forming. I have looked into other ways I could use to produce many cases that are the same. The main method I found that is worth considering is injection moulding. Injection moulding is a manufacturing process where heated plastic is forced into a mould cavity under pressure.
A mould cavity is essentially a negative of the part being produced. The cavity is filled with plastic, and the plastic changes phase to a solid, resulting in a positive. The machines then use high pressure to mould the plastic, Because of the high pressures involved, the mould must be clamped shut during injection and cooling. The two main plastics used are thermoset which cannot be resoftened after being subjected to heat and pressures; and thermoplastic, which can be repeatedly softened and reshaped by heat and pressure.
Both of these materials are fairly cheap and therefore will cut down on production costs. Also in vacuum forming plastic is wasted that was surrounding the case in the forming process this is then cut off to leave you with your case; this wastage is none existent in the injection moulding. The Plastics are not only very durable with their increased life-span but also easily recyclable. Most plastics can be reclaimed by regrinding up old products and using the pellets to make a new product which obviously means no waste.
In fact, plastics generally exhibit superior resistance to breakage and denting and are usable over and over again before recycling. The other main reason is speed, the injection moulding machine works continuously producing exactly the same thing every time but the vacuum forming machine takes longer to setup (plus it has to be set up manually) and therefore will take longer to produce the amount of cases required. I don’t have the equipment required for this job and would have to buy the cases in bulk from another company. For the base of my case I Would use C.
A. D C. A. M as an alternative to making it by hand. I could use a program such as Pro desk top to design the base to the correct size and select where the holes need to go for the circuit board. Then I could transfer the data over to a Computer added milling machine and replicate the design over and over again on one large sheet of Perspex. This would be extremely fast and I would be capable of carrying out the process. Another method would be making a Jig or a template. Then somebody could cut them by hand and still get every one the same.
When I manufacture this product in large quantities I will use a manufacturing schedule. My previous schedule will not be of any use as I will be using different processes to make my case. I will need to plan to change my plan to account for The injection moulding and for the C. A. D C. A. M. Circuit board. When I am producing my product in quantity I will use the same manufacturing order as before because this plan split up all the major parts of my manufacturing into sub-assembling groups meaning that time was used economically and mistakes could be spotted.
When manufacturing my circuit board jigs will be very useful for drilling the holes into the correct places on the board. This jig will save time and keep the level of quality very high. I could do this on C. A. D C. A. M as explained in the case although this may not be worth doing as a jig would be more effective. All of the components used will need to be brought in. If you by the components in bulk then their value goes down, also with resistors if you buy a higher tolerance for example 20% instead of 10% then the price also goes down but this may result in the circuit board not working.
The material for the circuit boards will also need to be brought in but the process of making the circuit can be done by us. When the circuit is being made I will follow the same sequence as before (see manufacturing plan) after every set of components has been soldered into place for example all of the resistors I will first visually check all the components then use a multimeter to efficiently and systematically eliminate any problems in the circuit before it is to late. Below are the checks that I will do after every set by doing this I will check for any short circuits or mistakes I have made and missed by looking for them.
1. Place the meter probes are on a path. If there is a voltage reading, the path is open 2. Place the meter probes on a path. If there is no-voltage reading, the path is closed. 3. Place the meter probes across a load. If a voltage reading is obtained, the load is receiving current. When the load is NOT operating, you should check for a grounded winding and for winding resistance. 4. Place the meter probes across a load. If there is no-voltage reading, you have an inoperative load. Replace the load. At all times safety must be remembered.
I have made some safety table on another sheet which show the processes which are undergoing in the making, the hazards that they contain, the procedures you must take and the treatment if injuries occur. If I was to mass produce my project then I would also look at decreasing the size of my circuit. Decreasing the size by even 1cm would mean that every 1meter square of circuit board I buy I can fit around four extra circuits on. This will save money in the long run so I will look at redesigning my circuit or decreasing its size before I started to produce large quantities of my product.