The above data was collected from a Low Velocity Forced Convection Oven. The temperature a product sees during processing and the time it is exposed to that temperature are two key components in obtaining consistent results. Therefore, both your profiler and conveyor speed must be in accurate calibration. Any type of profiler can drift out of calibration over time. You must check your profiler at least once a month using a thermocouple simulator.
Simulators are low cost items that can be purchased through most popular equipment catalogs.
If it doesn't, then your profiler should be calibrated. If you have a real-time profiler, such as those offered from KIC Thermal Profiling, you calibrate it yourself following the instructions in the User Manual. Attach a thermocouple to a PCB with a big glob of this solder an run it through a solder reflow oven. The temperature will then continue to rise steadily. Conveyor speed will also drift, and even when it's calibrated regularly, the calibration procedure is often not accurate enouth to ensure reproducible profiles.