Cushion Size

[black11455]

I have a issue with my shot size compaired to my cushion size, I read on an eariler forum that the cushion size should be 10-15% of the actual shot size. I have done the math and my cushion percentage is only at 2.5%, Is there any reason to be conserened? Or even more concerened that the machine runs 24hrs/5days?

[Suhas]

Hello,
Do not follow that rule of 10-15% - it is not right. Your cushion value should be small. On a 30-75 mm screw a cushion value of around 0.15" - 0.20" or about 4-5mm is a good number. The more the cushion the more inconsistency you get since the melt is compressible.
Hope this helps,
Suhas

[jayhawk1]

What was your cushion in inches or mm? If it is too small you can always move the whole shot back to add to the cushion. For instance if your shot setting is 50mm and you transfer at 8mm leaving you with 2mm cushion, you could move the shot back to 53mm and transfer to 11mm, which should give you a bigger cushion. Just be sure to move them both, not just one!

[nemanja]

Hi,

I have for diferent tools and products (same material) more less same cusion size, 4-5cm3. Shot size is from 10cm3 till almost 70cm3. So far never had problem.
I think is more important that you always have same cusion size, maybie around 5% of total cylinder volume.
BR,
Nemanja.