Determining Melt Flow Range of Product

Hello All -

I have been tasked with determining the average Melt Flow / Molecular Weight measurement for certain compound products.

I am collecting data by Polymer Grade type, and then formulation. For example:

Polymer Grade #1
Polymer Grade #1 with colorants only
Polymer Grade #1 with colorants and 20% Barium Sulfate
Polymer Grade #1 with 50% Bismuth Subcarbonate

Now for each category listed above - there may be 25 formulations that fall into that category. Because there is a slight variance on the actual ingredients going into the compound, the Melt Flow Range is somewhat different for each individual formulation.

While one formula gives me a range of 16 - 21 g/10, another may give me 26 - 50.

What is the best way to determine the average range? Do I just talley them all up and then choose the smallest and largest result and call that the range? Or is there a more accurate method I am just not seeing?

Thank you,
Nikki

 

How precise is needed?

From one point of view, "average" is meaningless...it is a different formula, therefore it is a different product, there for averaging it with another product has no purpose.

From another point of view, having an average for a family of products gives a chance to screen through your products more easily.

Which is the target? What you use the final result to accomplish may steer which calculation is most appropriate
MW is a fairly rough number to begin with...

 

No target - this is merely for a reference for Sales as customer's call them up and say they want a Polymer with a melt index of XXX g/10.

The information I am putting together will be the average range for each family of products as you put it.

What I am seeing - is that here and there are outliers.

So I took an excel spreadsheet and high-lighted the range of each formula that I found.

I think the way I want to do it, is to use a range that at least 3 of the formulations fall into, high-lighted below.

Does this make sense?

If I were to use this method, the range for this one would be 29 - 42 g/10 - and it would exclude those that seem to be out of the ordinary.

 

Whatever method you use...make sure that the folks using the info (salespeople) agree with it.

If it is a family of similar formulation, you might choose to take the median of each range, then break into families of similar median.

Sales literature is not a spec...but you might have trouble getting a customer to agree with that statement.
Make sure the range you set covers the normal variation of the product.

In your row#6, if you tell me that the range is 29-42, then ship me 27...we would have a problem...

 

Thanks Eric. This is going to be more of a reference for Sales - so that they know if the customer asks for a product with MFI range of X g/10 - they can explain to the customer almost immediately the "general" MFI range.

Melt Flow specifications are set once we have produced 3 to 5 lots - to come up with a specific range for that exact formulation.

 

Lol...sounds good. But you've gotta know it won't be used that way...

Scenario:
Customer: I want a flow range of about 30
Salesman: Any of these products meet that, here is the spec from our QC department (holds out the sheet of "general" MFI range you gave them)
Customer: I need the spec tighter than that
Salesman: No problem, we can do that...when will you order?
...and downhill it goes...

If it is going outside the four walls...make it tight, make it right.

 

And our regional Quality Manager has instituted a sign-off system for spec changes to address this very problem. For a spec change to occur, there must be agreement from Technical, Operations and Commercial. Unfortunately this doesn't address the millstones hanging around our necks from silly decisions in the past.