Saturday, October 4, 2008

How to Calculate Clamping force

as we know clamping unit purpose is to keep mold closed against force when part injected with plastic material, because of that clamping force at least more than injection force, we can applied this clamp pressure both in injection machine with hydraulic or with mechanical toggle.

Injection molding machines are usually characterized by the tonnage of the clamping force that they provide. The clamping force, indicates the amount of force that the clamping unit can apply to the mold to keep it securely closed during the injection of the molten plastic, picture below shown injection machine from Nissei with type NEX80 (80 ton)



formula
the clamping force is proportional to the projected area of the moulding and runner, and must be opposed by the clamping force. although a proportion of the pressure produced by the injection cylinder is transmitted to the cavity, various losses occurring in the heating cylinder, nozzle and gate we can consider that force acts on the mold to make it open can be calculated from the following formula:

Force (lb.) = Pressure (lb/in2) x Projected Area (in2)

what is projected area ? projected area is area that one line with mold base parting line, for complete calculation, calculate the runner projected area and part projected area is more precision. see picture below to get the imagine og projected area


Clamping force calculator
below are clamping force calculator using java script, the script i get from http://www.custompartnet.com, with little modification so it's more suitable with blogger post page.



Clamping Force





this picture below also have good visualization to explain projected area, clamping force and injection pressure


if you prefer see original calculator go to this webpage Clamping force calculator
but why i set safety factor 0.8, the result will more lower than without safety factor, in clamping force those formula is before correction for pressure drop and other, so the injection pressure always more lower than those manual calculation.

or we can use graph or table to define clamping pressure, like this one from niir.org

15 comments:

thank u very much for your information. expecting more details and specifications.

how to calculate runner projection area in 3 plate mould!!!

Hi
Thanks for the information ,but how to calculate the cavity presure

Hello all,
Could you please help to determine the clamping force generated by the clips which is being bolted with 2 bolts on each side. I have used M27x2 with the torque of 959 Nm. the diameter which had to clamped is 364. Kindly give valuable suggestion on how to proceed on this type of problem.

Hi there. Nice blog. You have shared useful information. Keep up the good work! This blog is really interesting and gives good details. Pressure Die Casting Machines, pressure die casting components.

Why the mold should close first then the injection unit close forword

How to calculate mould parting surface matching area by considering the moulding machine

How to calculate tonnage of injection molding machine

Thank you very much for the information, could you please me to calculate the cycle time in pressure die casting.

We have 250 Tons machine.Injection pressure is 1067 Kgs/Cm2. holdon pressure is 800 kgs/cm2.what is cavity pressure & what is clamping pressure.Pls.guide.

Dear hasnan

Its nice to recall old days of measurements

the most important part of plastic injection molding

thanks for reminding measurements

Thanks for our information,also on my website has some information for that:http://www.myplasticmold.com/widget-for-injection-molding-calculation.html

I really appreciated with it, This is fine to read and valuable pro potential, I really bookmark it, pro broaden read. Appreciation pro sharing. I like it.
This gives Acme Disys unconventionality in manufacturing unit. The company has made sure of deploying high end CNC machines & Vertical Milling Centres from Mazak, Makino and MoriSeiki for producing precision mold inserts and superior quality mold bases.

injection mold equipments | Plastic Injection Mould | 

Great idea. I enjoyed it. You have done a great job. Thanks for sharing. It help me a lot to get advanced information.


Nissei Machines

Very useful information in very fluid words. Could you please tell, can we approximately tell clamping force from machine motor power and average daylight?
Thanks in advance.