The purpose of back pressure in injection molding is to improve the homogeneity and quality of the molded parts by aiding in the melting and mixing of the plastic material. Dosing is the process of precisely measuring and delivering a specific amount of material into the mold, which helps to ensure consistent quality and reduce waste. Together, back pressure and dosing can help to produce high-quality, uniform molded parts with minimal defects.

This Back pressure study is done by measuring shot weight at approximately 95-98% full cavities.

1. Set up a standard optimized process for the mold.
2. Establishing a baseline: Remove pack and hold pressure (or set to machine minimum value).
3. Set backpressure to 0 bar
4. Adjust shot size until the most filled cavity is approximately 95-98% full.
5. Run 6 to 10 consecutive shots.
6. Weigh each shot and record the fill only shot weight.
7. Varying the back pressure: Increase the back pressure gradually by a few percent and run another 6 to 10 shots and record the same variables as in the baseline run at each back pressure level.
8. Analyzing the results: Repeat and analyze the data collected during the study to determine the effect of back pressure until a stable shot to shot weight is reached (minimum weight spread between the shots) with a acceptable feedingtime
9. Adjusting the back pressure: Based on the results of the study, adjust the back pressure to the optimal level for the desired molding results. "Select the backpressure with the minimum variability".

Overall, a back pressure study involves a systematic approach to evaluating the impact of back pressure on the molding process and identifying the optimal conditions for producing high-quality molded parts.