More Testing of RFID Shielding UNO Samples
Since my last post we have continued testing the RFID Shielding UNO samples, and we have some good news and bad news.
The good news is that we have had 100% success rate with all of the shielding tests we have undertaken.
Now for the bad news.... We have noted a consistent problem throughout our testing, and that is this new RFID shielding material is very brittle and ALL of the UNO samples developed cracks on either the front or back or both. Here are some photos.
As a result of these problems with the UNO samples we have been in detailed discussions with our moulding partners and the material suppliers to understand the reasons for these problems and attempt to find a solution. The cracking problem in the standard UNO samples is caused by a number of issues...
- Wall thickness too thin - needs to be 3mm min for this RF shielding material.
- Single injection point at the base of the Card Holder causes weld lines which are the weak failure points. This can be overcome by utilising what is known as a hot runner system that provides multiple injection points, but this increases tooling cost threefold.
- High proportion of Carbon and Nickel fillers in the material (provides the RF shielding) weakens the material and causes brittleness.
There are solutions to the above issues but they all come at a price...thicker wall sections and therefore bulkier product and more expensive and complicated tooling.
There are also other problems associated with using this material.
- Material cost as I have previously advised is very high. This is exacerbated by the fact that this material cannot be recycled which in turn leads to a higher unit cost because of the processing difficulty and the subsequent low yield rates
- The high (RF) filler content in the material is very corrosive to the injection moulding machine screw and barrel (this is the part of the machine that actually injects the molten plastic into the mould), which in turn translates to a shorter service life for these components with a very high replacement cost, which ultimately must get passed on into the unit cost of the product.
- This material has very poor flow characteristics during the moulding cycle as a result of the high filler content. The picture below shows a "Short-shot" when we tried to use the moulding parameters of our existing UNOs for this new material. This ultimately translates into a longer cycle time and therefore higher component cost.
In consideration of all of the above problems we have determined that it is not economically viable to continue this RFID shielding material and we have therefore reluctantly decided to drop this from our UNO program. We will however still proceed with a Kickstarter campaign for 5 and 6 card UNOs using our standard materials. It is my intention to launch this campaign within the next few weeks.
Kevin + KWA Design team