aluminum mold surface question

[rwolf]

we are building a 5'x7' aluminum female mold for an embossed pan face. my question is what grit sandpaper should we use on the mold to avoid vacuum trap? this mold is currently in production and this q' is my only hitch. thank you.

[spektr]

Female molds do not depend on sanding the tool surface to completely vent. You must properly port the tool to make that happen. Surface sanding is used only in cases where local areas of a tool surface cant vent to the facet edge. This is different from porting. It is possible to get the tool too smooth and sanding will help that, but there is no RULE about it. It's an on demand cure for a specific issue. Finish the tool, pull a part or 2, look at what issues you need to cure. If you can't tune it, come back with specific questions/photos and we'll get them up.

Scott

[rwolf]

so i think that this is vaccume trap. please help. mold surface was 320 grit now i have it @ 80.

[spektr]

Well I dont see any holes to remove air from the cavity. Ideally this should have been a male mold with thte plastic being pulled down onto it. But since you are here, lets try to fix it.. How is the vacuum applied to the tool, show me the plumbing. If you are using amall holes in the corner of the cavity, its no wonder you are having issues. You might need to drill a number of holes in the corner of ther "face depression" to get it to work. i'd suggest 1/32 inch holes every inch around the inside margin og the depression. Those shouldnt show up in th efinished part if you bury them in the radius of the corner......

Scott.

[rwolf]

this was built as a female mold do to the fact of having 2nd surface vinyl film already applied to the sign face b4 forming. . . i have holes appox. every 4 inches around the "face depression" . . i also have holes appox. every 6 inches around the "pan" portion of the mold . . our vacuum holes are #58 drill size . . plumbing= 2" dia. rubber hose connected to the mold box located bottom center, with a 2" black pipe flage/ elbow/ barb fitting . . pics pending

[rwolf]

appox. 15-#58 holes are also drilled in the "face" area on the flat plane