Help Troubleshooting DIY Injection Mold for Small Card

[Mike28303]

A question on the part design. What is the thickness? Thin sections are very hard to fill, on parts I designed (using nylon 6) we used .050" as the absolute thinnest section that would fill without issues. .080" to .090" would be even better.

The thickness is .03", across the whole length of the 2" x 3" card. I'm about to do a test heating the mold to the melting temperature of the plastic, as others here have suggested. I don't think the hand-operated injection machine was meant for a part like this, but I really want to make it work.

 

[Plas62]

.030" is pretty thin. If you can increase your part thickness as Sanddan suggested you will have a better chance at success.

If you goggle "recommended wall thickness of abs parts" you will get some hits. I copied and pasted some info below that I found.


Material

Recommended Wall Thickness
ABS 0.045 in. - 0.140 in.
Acetal 0.030 in. - 0.120 in.
Acrylic 0.025 in. - 0.500 in.
Liquid crystal polymer 0.030 in. - 0.120 in.
Long-fiber reinforced plastics 0.075 in. - 1.000 in.
Nylon 0.030 in. - 0.115 in.
Polycarbonate 0.040 in. - 0.150 in.
Polyester 0.025 in. - 0.125 in.
Polyethylene 0.030 in. - 0.200 in.
Polyphenylene sulfide 0.020 in. - 0.180 in.
Polypropylene 0.025 in. - 0.150 in.
Polystyrene 0.035 in. - 0.150 in.
Polyurethane 0.080 in. - 0.750 in.

 

[petertha]

Hope you get your issues resolved. This is fascinating. I'd like to see some pics of your setup one day. My hack amateur work is pouring vacuum de-gassed 2-part urethane resin into molds, but that's certainly not a production operation & limited to the properties of the resin which are probably different to the plastics you are using.

 

[sanddan]

.030" is pretty thin. If you can increase your part thickness as Sanddan suggested you will have a better chance at success.

If you goggle "recommended wall thickness of abs parts" you will get some hits. I copied and pasted some info below that I found.


Material

Recommended Wall Thickness
ABS 0.045 in. - 0.140 in.
Acetal 0.030 in. - 0.120 in.
Acrylic 0.025 in. - 0.500 in.
Liquid crystal polymer 0.030 in. - 0.120 in.
Long-fiber reinforced plastics 0.075 in. - 1.000 in.
Nylon 0.030 in. - 0.115 in.
Polycarbonate 0.040 in. - 0.150 in.
Polyester 0.025 in. - 0.125 in.
Polyethylene 0.030 in. - 0.200 in.
Polyphenylene sulfide 0.020 in. - 0.180 in.
Polypropylene 0.025 in. - 0.150 in.
Polystyrene 0.035 in. - 0.150 in.
Polyurethane 0.080 in. - 0.750 in.

Those numbers make sense, my parts were 30% glass filled nylon so my min of .080 closely matches the chart's .075.