After sending Tip #15: “What are Fill and Pack?” I got some questions that showed confusion between machine fill and pack v.s. cavity fill and pack.
The short explanation is this: Cavity fill is when the material reaches the end of the cavity so that it can begin to pressurize. Machine fill (in a decoupled process) is when the machine slows down (D3) or transfers to hold (D2) BEFORE the cavity is full. The melt then decompresses and the machine slowly packs more material into the subsequently full cavity.
In the eDART we want the user to set the fill volume for a particular process. This is either done with the cursor on the cycle graph, or a button on the Sequence Settings fill tab (with a short shot) or by typing in a number. If you don’t set fill volume then the eDART uses the time at injection pressure peak. This tells the eDART when the fill portion of the cycle ends from the machine’s point of view.
The cavity fill settings in “Sequence Settings” tell the eDART when to interpret the cavity as full. Experience has shown that using 1000 psi at the end of cavity is a good estimate of a repeatable fill time.
The Sequence Settings tab lets you change the meaning of when a cavity is full. These are saved with the processs, i.e. the mold / material /cavitation combination.
This tip is focused on fill. The pack settings follow the same idea. Machine pack ends at transfer. Cavity pack starts at cavity fill and ends at 98% of the Post Gate sensor peak. If there is no post gate sensor you must choose another that exists. If someone needs more elaboration on machine v.s. cavity pack, let me know. This is probably a separate tip.
More Details for Those Interested: Values Computed
Knowing the end of machine fill allows the eDART to compute viscosity during fill, machine fill time and speed (for repeatability and process setup). It does not tell you how fast the cavity filled to the end. The sequence trace Machine Sequence/ Fill comes from this computation. The summary values are:
The eDART uses the Sequence Settings, Cavity Fill setup to decide when the cavity is full. It can then compute a variety of summary values that represent part quality in-cavity far better than the machine variables.