Here is another problem I would like to get feed back from all the experts here. It does really help to bounce ideas off other people even if you are sure you know the answer because it allows you to sit back and think from different angles.
Customer called me in complaining of bubbles/blisters around the gate area. My first though was moisture of course since this is a nylon 6 25% glass/mineral filled material. In this case though I thought it was an over dry due to the fact we sent it in at 0.05% and they dried it after that. They do not utilize a moisture analyzer by the way.
The investigation led me to do a audit on there hot runner system. The first thing I noticed was this customer is running barrel temps at 500F across and manifold and the drop temperature at 440F. I have never seen that much disparity in temperatures, especially on the low side. I have seen them to high due to undersizing of the hot runner system. I looked at the gate (which I have attached a picture of) and almost laughed out of disbelief of what I was seeing. My conclusion is that the gate is producing so much shear heat that it is causing the degradation of the nylon. The only area affected is a 4" diameter around the gate. This is a big part and they have gated it in a corner where it must flow around 25" to fill. That is an issue in it self but it is automotive and the automaker insisted on doing this.
Please give me your thoughts on this..thanks
Technical Service Manager
Customer called me in complaining of bubbles/blisters around the gate area. My first though was moisture of course since this is a nylon 6 25% glass/mineral filled material. In this case though I thought it was an over dry due to the fact we sent it in at 0.05% and they dried it after that. They do not utilize a moisture analyzer by the way.
The investigation led me to do a audit on there hot runner system. The first thing I noticed was this customer is running barrel temps at 500F across and manifold and the drop temperature at 440F. I have never seen that much disparity in temperatures, especially on the low side. I have seen them to high due to undersizing of the hot runner system. I looked at the gate (which I have attached a picture of) and almost laughed out of disbelief of what I was seeing. My conclusion is that the gate is producing so much shear heat that it is causing the degradation of the nylon. The only area affected is a 4" diameter around the gate. This is a big part and they have gated it in a corner where it must flow around 25" to fill. That is an issue in it self but it is automotive and the automaker insisted on doing this.
Please give me your thoughts on this..thanks
Technical Service Manager
