locking ring mechanism advantagesv2

7/28/2019 Locking Ring Mechanism AdvantagesV2

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Avrand Plastic

Salvador Rodriguez

Locking Ring Mechanism

Salvador Rodriguez

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Avrand Plastic

Salvador Rodriguez

If we consider also that many of the cars in Iran use CNG, this makes the Gasoline refilling

time period to extend more than normal and in the mean time the Gasoline tendency is to

gasificate because of the temperature, increasing the internal pressure of the tank. This

constant pressure and temperature per days & months makes the tank & Plastic Thread of

the Tank to deformate and grow, changing the features of the locking .

Effect of the Temperature and Gasoline to the Plastic Locking system

The HDPE is a Semi Crystalline Polymer were its molecules are surround of many empty

space, this makes the HDPE to permeate and to let pas the Gasoline through it, of course the

amount that pass it is accepted under the Euro 2 regulations.

In other hand it is well know that the high temperatures during Spring and Summer makes the

Polymers to changes its dimensions, the long time exposure to the temperature and to the fuel

for many days makes the molecules of the surface of the part to get close to the glass transition

were the molecules get some free motion generated for the thermal Energy.


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Avrand Plastic

Salvador Rodriguez

In the consideration of the increment of pressure on the tank, the Metal Locking Mechanism

does not give a chance to brake the locking ring as the plastic nut has.

Effect of the Temperature and Gasoline to the Metal Locking system

The material of the fuel tank does not change at all, still HDPE is a Semi Crystalline Polymer

and the consideration are the same.

In the consideration of the temperatures during all the seasons, the Metal locking mechanism

has more advantages of not change so drastically its dimension against the Polymer

mechanism. This ensure the seal of the fuel tank for largest time.


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Avrand Plastic

Salvador Rodriguez

Scrap on Production Dep. due to leaks of the locking system

There has been many reasons that make our tanks to leaks and we can consider between them:

Change of Material Brand that include change of the mechanical properties on the HDPE.Change of % of BOM of the tank that makes the tank mechanically weaker.

Change of waiting time for get final dimensions before welding(affect on the ovality).

Change on the Cooling Fixture(pump area).

Change on the O-ring Design

Different dimensions of the Nuts coming from different cavities.

Different dimension of the Pump Head coming from different cavities.

Now we are aware of all of this and we are working on solutions for all of this but there is fact

that we wont be able to get rid of: The Plastic locking system can be affected for many reasons,

and we need a solution that has less variables to control and that reduce our scrap.

Avrand could reduce the scrap due to leakage of the tank if we use metal locking system.

Comments from one Process Engineer:

Using the encapsulated ring allows for a more robust and consistent seal while o-ring / gasket is used tomaintain the seal.

There are some issues even with the encapsulated ring, the surface for the o-ring must be good, no grooves,

lines or contaminations, surface must also be flat and be of the correct depth, these are all part of QC

checks.

But, I think when all the options and potential problems are reviewed; the encapsulated ring is still the best

solution, as it is more consistent and repeatable.


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Avrand Plastic

Salvador Rodriguez

After Sales claims due to broken nuts , dimensions of tank thread.

We have reports from the After Sales Department showing that our tank after 8 months grow, and we notice

this more on the pump area, because many nuts has get broken and in the moment of trying to replace it, the

service Department can not close again a new nut over the tank.

Even we have work out to reduce the dimension of the thread of the tank to reduce the

possibility of braking the nut, all the assumptions mentioned before still are valid and true.

The customer complains about broken nuts and closing mechanism out of dimension will be

eliminated if we change the locking system to Metal .

Comments from 2nd Process Engineer:

I never liked the plastic thread. The repeatability of the thread is low.

For seasons the process was semi stable in large mass productions, but sometimes,

we had many problems to keep the dimensions inside of tolerances and we had leak issues.

The TI corporate decided to quote for the new projects mostly E-rings to reduce the after sales claims and

reduce our internal ppm.


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Avrand Plastic

Salvador Rodriguez

Features Metal Lock Plastic Lock

Resistance to Gasoline & changes of Temperature X

Reduction of Scrap due to leaks X

Reduction of After Sales Claims X

Euro 4 & 5 Technology

Euro 6 Technology X

Low Price X

Material can be recycle inside of Avrand Factory XRobust System ( System can not be brake due to

pressure)

X

Tank that leaks can be reworked

Repeatability of Dimensions X

Summary of Advantages & Disadvantages


7/7 Avrand Plastic Salvador Rodriguez

Thank you

locking ring mechanism advantagesv2

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