Open rate is a very important factor for pellet die, it affects not only die working life, but also production. So how should we calculate the open rate?
Open Rate=area of hole/area of work path
PS: We should notice that the work path size should follow the die inner part, rather than outer part.
For example, model SZLH420C, hole size 8.0mm, hole per circle: 122, raw: 12, total 1464 holes
Area of hole: 3.14*4*4*1464, come 73551.36mm²
Area of work path: 3.14*420*120 comes 158256mm²
Open rate: 73351.36/158256, comes 46.48%.
Why we can’t calculate the open rate with its outer part? If we change to this way, calculate way will also be changed.
For example, model SZLH420C, hole size 8.0mm, If we want to keep same open rate above, we will need guarantee the hole area should be 101295.14mm².
Area of work path: 3.14*580*120 comes 218544mm²
Hole/circle should be 101295.14/3.14*4*4*12, comes 168 holes, which means the hole pattern becomes 168*12. With the design 168*12. Outer side is ok, but inner side holes are mixed together. The die is scrapped.