Injection heating issue

Hey, thanks in advance for any input, really stuck here.

the bottom 2 heat bands on my injection machine were taking a really long time to heat up, while the top 2 heat bands were up to temp in 9 minutes.

I first tried moving the top two bands that were working well to the bottom position closer to the nozzle to have the consistent heat there. After I moved them, the problem switched. Seems that whatever bands are on the bottom take 45 minutes to heat up.

I tested my thermocouples.

I made sure all settings in PID were the same.

I changed my PID.

I changed the SSR.

I still have the same problem. Whichever bands are on the bottom close to the nozzle, heat very slowly.

I’m lost at this point. It’s my first machine and the guy I bought it from doesnt respond and sold me a machine put together lazily.

Can you take a picture of how the heaters and thermocouples are mounted?

Glad to hear you stuck with it and are in production. 12 per hour is a very good throughput. That’s a nice wax comb.

Thanks for your thoroughness, I don’t know what I would have done without the responses from you!  All in all it’s going well, still having problems but will try some things tomorrow.  I went thru my entire control box and made sure everything was tight, which it wasn’t.

The builder sent a half ass, “ready to assemble” product and customer support was bad at best.  Still don’t have the hopper which was supposed to be sent.  Their photo on the bazar has Inkbird PID’s in the photo and ships with REX knock offs.

But the silver lining is that i have learned a lot.  I hope your projects are going well!!!

wow, thanks for all the input, I am slowly going thru all the responses and looking into them on my machine.  i bought some new band heaters but they are too big.  One does fit on the nozzle so maybe its not a bad thing.

The new heater works and I will try the other tomorrow even tho there is a size issue.  Looks to be that maybe i have some faulty band heaters or they went bad some how.

But with all the issues, I have been able to pump out some products; with PP, I have been able to do around 12 per hour.  I still have bad presses but am getting better.  With HDPE, I am at about 5-7 per hour and need improving.

All in all, I’m really happy to be doing this and I can’t thank you enough!

I think someone posted links to higher quality heaters but I just use the Banggood type stuff for what I do. I would just make sure the tube and structure is grounded in case one of the cheap heaters fails in a bad way.

Hi s2019,

Thanks for your reply. I found the bundle on Banggood and ordered the PID controller, SSR, Thermocouple and also the bandheaters, led indicator and power switch.

Do you know of any other premium bandheaters to buy? The ones I have bought seem like cheap Chinese stuff.

They are readily available online (amazon, Ebay, your favorite Chinese vendor).
The best deal is to get the PID/SSR/Thermocouple bundle which can be found at very low cost.

I hope you get your machine working soon mate, and I’m very sad to hear the machine builder ain’t supporting you.

Guys – Where do you buy the thermocouple?

It looks like they are called k probe thermocouple. I think of thermocouples as solid state, not electrical, but now I know . They are almost certainly set specific to different PIDs. If the builder just grabbed one for a different brand, say Inkbird vs uxcell, then they might not work together.

I was thinking maybe the sensor was not of the same range/rating as the other. I think they are referred to as a k sensor. So if it “senses” that it is at or near desired temperature it just pulses the current to maintain. This could explain finally reaching temp, just slowly. Maybe just swap the sensor out with each other and see if the issue follows. Are the part numbers on the pids, heater coils, and sensors the same for each? Same pids, same coils, same sensors I mean.

For the thermocouples, their tips should be pressed against the tube but not the heater. Take a picture of one of them.

I think since the problem is slow warm-up, Most of that time the PID should be full on so I suspect you have 220V rated heaters and the one near the tip just does not have enough power at 110V to heat that part of the tube and maybe the aluminum frame fast enough.

I think you said you tried swapping the heaters and PID’s and it did not change.

If it is just a slow warm up, maybe you just live with it or if it is the wrong heater, You can get a 110V heater for the nozzle for not too much money on ebay. Too bad the builder isn’t helping you here.

So a thermocoupler issue?

Great stuff, thanks so much. Will go thru all of this today. It’s all new to me so I am learning a lot and your input is invaluable.

The closer I look at the pictures, the more I think you have a temp sensor near the tip that is telling the computer it is hot enough or near temp so the pid is sending less current to that set of heaters.

It seems to me that you either have coils of two different internal resistances, or the current settings to one set is different than the other. It would be almost a certainty if you take the high performing set, and swap their positions. Do not undo any connections, or change anything else, just locations. If they then don’t get hot you have a ghost; because that makes no sense. Sorry, I have a hard time explaining through text. Conversely, you could leave the heaters in their current positions and change only the wiring. Don’t get overwhelmed,  the issue is almost surely one of the following:
1. Heaters of different internal resistance.
2. Current settings  are too low for one set of heaters.
3. Faulty wiring
4. A temperature sensor sending an incorrect signal.

Will do, thanks for the tip.

When he comes over, I’m sure he will do it anyway, but ask him to check that all that metal framework is properly grounded.

Good luck

I will check the plate today. We only have 110V in Panama. My girlfriends father is an electrician, I will have him come over to help. Thanks to you guys who have responded. What a great community.

Does that aluminum support plate get very hot? if it is in good contact with the bottom heater, you may be loosing some heat there. If you have a multimeter you could check the resistance of the heaters. Do you have 110V in Panama? If those are 220V heaters then you are only getting 1/4 of the rated power.