[laminated]

Hello everyone, I'm planning on building a ram style plastic injection molding machine and wanted to know what materials people had good results with for the injector barrel and ram?
I don't plan on using any plastics with chlorine so I'm not sure I really need it to be stainless steel.

I've seen people make them out of aluminum which sounds like it will just gall quickly. I've also seen people use DOM tube.

I have a few pieces of 1144 that I could use. I'm planning to use it mostly for PETG. Any advice on this is absolutely appreciated!

[mactec54]

Hello everyone, I'm planning on building a ram style plastic injection molding machine and wanted to know what materials people had good results with for the injector barrel and ram?
I don't plan on using any plastics with chlorine so I'm not sure I really need it to be stainless steel.

I've seen people make them out of aluminum which sounds like it will just gall quickly. I've also seen people use DOM tube.

I have a few pieces of 1144 that I could use. I'm planning to use it mostly for PETG. Any advice on this is absolutely appreciated!

1144 would be ok the piston will have to be a similar material because of expansion so need to be close to the same, the 1144 is free machining so won't be much better if any better than Aluminum, the 1144 will hold the heat better I use a tool steel H13 for injector barrels

[laminated]

1144 would be ok the piston will have to be a similar material because of expansion so need to be close to the same, the 1144 is free machining so won't be much better if any better than Aluminum, the 1144 will hold the heat better I use a tool steel H13 for injector barrels

Thank you for your reply. H13 sounds like a damn good material to make one from.
I realized that making it from 1144 is essentially a disposable barrel.

I thought about useing something like 1045, but thought that 1144 would be more stable ones heated.

[mactec54]

Thank you for your reply. H13 sounds like a damn good material to make one from.
I realized that making it from 1144 is essentially a disposable barrel.

I thought about useing something like 1045, but thought that 1144 would be more stable ones heated.

Yes use what you have you can always make it better if you have too, 1045 is not so good to machine but you could bore and have it honed, then make the piston to suit

[laminated]

Yes use what you have you can always make it better if you have too, 1045 is not so good to machine but you could bore and have it honed, then make the piston to suit

Unfortunately I don't think my small lathe (pm1228) is up to turning h13. Not sure if it's always prehard. I was looking into 304. But I see it has a much higher thermal expansion.

I would assume it would be less likely to crack from thermal stress similar to cook where.
I see 304 is also available for a lot on injection components. So not sure how bad of an issue the extension is in real practice.
For a screw I could see there being issues, but for a ram injector system I think as long as there's good clearance it will work fine.

[mactec54]

Unfortunately I don't think my small lathe (pm1228) is up to turning h13. Not sure if it's always prehard. I was looking into 304. But I see it has a much higher thermal expansion.

I would assume it would be less likely to crack from thermal stress similar to cook where.
I see 304 is also available for a lot on injection components. So not sure how bad of an issue the extension is in real practice.
For a screw I could see there being issues, but for a ram injector system I think as long as there's good clearance it will work fine.

H13 I would say is easier to turn than 304

303 is free machining and would work just as well as 304 the only real different is that 304 is ok for welding 303 is not so good

[laminated]

H13 I would say is easier to turn than 304

303 is free machining and would work just as well as 304 the only real different is that 304 is ok for welding 303 is not so good

That's pretty surprising. Not really more expensive than stainless for the small size I need. Can it be drilled with cobalt hss? Also is it difficult to tap?

[mactec54]

That's pretty surprising. Not really more expensive than stainless for the small size I need. Can it be drilled with cobalt hss? Also is it difficult to tap?

Yes, quality regular HSS drills are ok, it taps ok with again quality taps, normal cutting fluids are fine

[mari-ee]

Hello everyone, I'm planning on building a ram style plastic injection molding machine and wanted to know what materials people had good results with for the injector barrel and ram?
I don't plan on using any plastics with chlorine so I'm not sure I really need it to be stainless steel.

I've seen people make them out of aluminum which sounds like it will just gall quickly UK plastic recycling services. I've also seen people use DOM tube.

I have a few pieces of 1144 that I could use. I'm planning to use it mostly for PETG. Any advice on this is appreciated!

For your project, 1144 steel is a solid choice—it's strong, wear-resistant, and great for PETG. Just ensure the surface is polished to minimize friction. Stainless steel (like 304 or 316) is also good for its smooth finish and durability, even if you’re not working with chlorine-based plastics. DOM tubing is another reliable option due to its strength and smooth internal surface, though pairing it with a hardened ram can help with wear. Aluminum is likely to gall and wear quickly, so it’s not ideal for your needs. With 1144, consider surface treatments like nitriding for added durability.