Hi gr5, thank you for your comment. And sorry for my late response, I've been busy at work!
We are indeed printing with a high temperature material, in the case of the measurements with white PC. I understand that we can 'boost' the temperature by covering the machine. But should that be necessary? It looks obvious to me that the printer should be able to warm itselve up to more than 90°C, but I can be wrong. Also, we've printed with PC and many other materials before without this problem.
By the look of your posts, points and owned printers. Could you tell me if the temperature raise on our printer is considered 'normal'?
Also, I've made a screenshot of the notification we get from our UM3E.
Looking forward to your response. Thank you!