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One of the interestiing topic everyone contributing their experience / thoughts.....

LSasso,

Please watch carefully whether the screw ( NOT NOZZLE ) is retracting before refilling starts, in...

Hi,
Is this problem are you facing with and without nozzle retract ? Please check this effect without nozzle retract if you are using the same one.

Thank you alice,

Still we have not fixed the problem....looking the option of changing gate location / product modification.
Will keep in touch with you,

Warm regards

Thanks to all for giving your thoughts.

We have tried with increased gate size , Filling time varying and step injection . But all trials have sink mark in the part.

Rgds,
Maheshkumar

gate ( Dia 1.1 * 1.2) and gate freeze of time is 3.0 sec.

Ejection Temp - 50 * C.
Steel temp 58 *C.
MTC temp 60*C.
Colling time 10 Sec ( Tried up to 15 Sec - but no chnage in the sink mark)
Degating is smooth
No stress mark on the part noticed at...

It is Coldrunner Submarine gate..

Thanks for your quick reply...
IT is Nylon 66. Wall thickness in gate area 1.02 mm. Overall average part thickness 2.50mm.
And also noticed these sink marks in short fill itself when the parts are...

Hi ,

I came across the problem of Sink mark near the gate ( Dia 1.1 * 1.2) in one of the connector housing.The raw material used for the same is Schulamid 6 mu 14 FR (PA 66).It is a 2 cavity...

Look the option of making Standard Spure bushing, It will help you in narrowdowning the problems and may give you some hint on finalsing the nozzle size.

Maheshkumar

Hi Friends ,

I am interested to know what is the best acceptance tolerance for part weight for tight tolearnce parts ( EX..Connectors ...)

Hi SM,

For which plastic material are you facing this problem ?

What are the process variation for Melt cushion and inj pressure and dosing time ?

Thanks ,
Maheshkumar.

Thank you ,

We are making tight tolerance parts ..sometimes the tolerance are to be less than 50 microns...and using engineering plastics ...LCP,PBT,PA66,PA46........

Hi friends ,

I just want to know the best practice to conduct ring plunger test in injection molding machine.

Dear Friends,

I have a question to ask for the tolerance to set for molding parameters like...What are the industry standard tolerance for a better process control.

1.Injection Speed ...

I go by weight .. which gives right direction of going forward....

Nathan ,

Can you plesae share in detail ? As I want to have some wrae around 5- 10 % variation . Please share the details to mhiremath@molex.com.

Hi all,

Usually i go by weight

Short term cources are helpful a lot , Many institutes conduct such coures on Machines, process and materials.....found out one in your location.

Suhas Sir,

1. To take 10 shots, is it required to turn OFF holding parameters ( time and pressure ) or with holding parameters turn ON.?

2.Please elabrate how to do Inj speed linearity test....

During 1st filling ( Injection phase ) , is it right practice to turn off both holding pressure and holding time ? :confused: