Charging help

[Rohit876]

Hi everybody,

i am new to injection molding and was facing a technical problem. With no service around, thought would take help from you people.

we have two injection molding machines of the same make, specifications, etc. we are running pet performs on these machine.

On one of the machine while running a 16 cavity preform Mold we are getting a cycle time 28 seconds and on the other a cycle time of 25 seconds when we are running the same Mold. On investigating the same, the problem was found out to be slow charging.

on further investigation we found that in the machine that was running on 25 seconds the charging pressure is 100 bars and in the relief valve there was a voltage of 1.3 while charging was going on.

on the slow machine the charging pressure is of 50 bars and there is no way I am able to increase the pressure. Also when the charging is taking place the relief valve is showing no voltage. Also the cycle time is not stable. It sometimes goes to 28,29 and then comes to 27.

please inform whether I am going in the correct direction and how to resolve this issue.

Fyi the machine are of Chinese make and no help from the manufacturers.

thanks a lot already

[Suhas]

Hi Rohit,
The only option I think you have to get the machine fixed. Others will chime in here and hope they have a better answer.
What about the screw speed? Can you increase that?
Suhas

[Rohit876]

Hi Rohit,
The only option I think you have to get the machine fixed. Others will chime in here and hope they have a better answer.
What about the screw speed? Can you increase that?
Suhas


Hi Suhas,

No way can manage screw speed either.

Regards,

[moldingppm]

What machines are we talking here? Brands?
As far as the no voltage, have you traced wires? As in is something broken?

Welcome to the world of Chinese machines, lol

[Rohit876]

What machines are we talking here? Brands?
As far as the no voltage, have you traced wires? As in is something broken?

Welcome to the world of Chinese machines, lol


The machine here is HMW 2280F5.

We have traced the wire. Do not find any problem. It does show voltage when other functions are on. Only when charging is on it is showing 0 voltage. Something somewhere seems wrong. Unable to figure what.

Hope you are able to help

Regards.

[Pilot]

Hi,
if I remember, HMW machines are using Vickers components.
your issue could be realy somewhere :-)
But if you have a two identical machines, you can compare values between machines. My idea is to swap charging valves between machines and you will see, if the problem is going with valve or not..... or swap pressure sensors.
If not, please start with meassurement of voltage directly on the Output control card. sipmle way is replace cable with temporrary wire directly from control card to valve.
You have to go step by step....

Pilot

[Rohit876]

Hi,
if I remember, HMW machines are using Vickers components.
your issue could be realy somewhere :-)
But if you have a two identical machines, you can compare values between machines. My idea is to swap charging valves between machines and you will see, if the problem is going with valve or not..... or swap pressure sensors.
If not, please start with meassurement of voltage directly on the Output control card. sipmle way is replace cable with temporrary wire directly from control card to valve.
You have to go step by step....

Pilot

Yes Pilot, you are correct hmw is using vickers.

1. Charging valve already swapped. Same problem.
2. By pressure sensor you mean pressure guage?
3. Please explain detail what needs to be done with the output control card. I am sorry could not get it.

someone also suggested to exchange output card between the machines. Is that a good idea?

please could some one also explain the significance of:

1. Is it alright if the voltage in the flow control valve is above 33. Shouldn't the voltage be maximum 24.
2. What is the significance of 1.34 voltage in the relief valve located in the double proportion board while charging.

regards

[Suhas]

Rohit, Beat up (not literally :) ) the salesman for the machine. Tell him that you are not getting support. Sales guys will put pressure on the tech guys because they have to see you more machines in the future.
Sorry not a technical answer.
Suhas

[Pilot]

Hello,
OK, it looks, that it is no issue with valve.
Could you place here a hydraulic schema for this machine?
Only for my better understanding - by the"charging" do you mean plastication? (stupid question, but english is not my native :-)
I can not recommend to swap I/O card between machine. I do not know system of haiming machines.

You are right with overvoltage. Could you check calibration values for charging valves? Should be similar on both....

BTW: where are you from?

[sullivan]

I think you should adjust the correct charging pressure and screw speed.

[sullivan]

BTW:How long your machine used?Maybe ,some parts need to replace,for example:valve,heater...

[Rohit876]

BTW:How long your machine used?Maybe ,some parts need to replace,for example:valve,heater...

hey everyone,

Thanks for the help. From Nepal

Changed cards between the machine and figured the pressure proportional valve was bypassed while charging (plastication). This was done because there was a lot of pressure on the cover end pump. IT was making a lot of noise.

Now could someone tell me how to be sure that I need to open my pump or hydro motor. Anyone in India or Nepal to help?

Regards.

[Pilot]

Hi,
Unfortunatelly I am from Czech ....... but nice vacation in Nepal..... hmmmmmm :-)
Noisy pump - it sounds not good.
Do not open pump. you are not able to repair it correctly.
Could you check a oil quality? Is oil like oil or like dirty milk?
I do not understand, how you bypassed the valve .....
.... and what is noising? Hydromotor (Intermot) or hydraulic pump (I think it is Eaton)?

[ArikB]

Do a rear zone tact temp study to determine the proper temp to set your rear zone at. This is often overlooked by molders. Your plastic needs to "slip" on the screw and "stick" to the barrel. After youve determined the ideal temp I bet you get a LOT better consistency.