Hello,
I have some experience from the industrial vacuumforming (fridge production with PVC).
It's quite important that the core temperature from your plastic sheet is higher then the glas transition temperature but not so high as the melting temperature. If the temperature is below the glas transition temperature, you will get some cracks in the plastic during the forming. Also the tempering of the mold is quite important, with a "hot" mold (30-50°C) you get better results during the forming (the material can flow better).
In the fridge mass production we used a lot of sensors to control the plastic sheet heating process and also the forming process itself. But nevertheless, we set the parameters for each new product with the try and error method