1.06?

[Valentin Leung]

Hey,
I saw that in the Suhas book, in some formulas, we have 1.06/(Density of the machine) in the capther 6. Can anybody tell me where the 1.06 is coming from?
Thanks and Regards

[farhan]

I have the same question asked by Mr. Valentine.

Residence time = ((Shot capacity of the machine)) /({(Part weight × Number of cavities) + Runner Weight) × (1.06/(Density of the plastic))) × Cycle time

Percent Shot Size = ([{(Part Weight ×Number of Cavities) + Runner Weight} × (1.06/(Density of the plastic))]) /(Shot Size of the machine) × 100

In both the formula above the author used 1.06 to calculate Residence time and Percent Shot Size. Can somebody enlighten us on this topic.

Thank you very much for your kind attention.

[brentb]

The density of the resin in question would be 1.06 grams per cubic centimeter (1.06 g/cc).This is compared to water, which has a density of 1, as I understand it. PE or PP which has density<1 would float.

KOM

brent

[JayDub]

Manufacturers state the shot weight/capacity of their machines in terms of GPPS, which has a density of 1.06. To estimate the shot capacity for other resins, you need to divide the given rated capacity by 1.06 and multiply by the density of the resin you are using. This is what is happening in the equations cited, although it's buried away in the other calculations.

[Suhas]

Sorry for the delay guys,
Yes, JayDub has it written correctly and Brent has it described correctly also. It is a comparing against GPPS. General Purpose Polystyrene was the default material that they used to specify the shot sizes. So the barrel volume would hold 100 gms of GPPS. Now if you are molding a material that has a density double that of GPPS, so = 2.12 gms/cc (I am choosing this number for simplicity) then the same volume will hold double the material by weight = 200 gms. So now the shot size with the new material is 200 gms. One must convert to the material that you are molding.
Let me know of any questions.
Suhas

[Valentin Leung]

Thanks a lot, in our machine, they specced it out with GPP instead of GPPS. So we were not sure where it was coming from, but now, it's clear.
Thanks again