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)

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, 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


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

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

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

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:

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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.

what is the meaning of 90/210 of a HM SERIES BATTENFELD MOLDING MACHINE

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Thank you so much. I was quite interesting. check this out, you will like it.

How we can calculate the clamping force for injection molding machine & tonnage , ple explain it, with example

you all doing wonderful job.Keep it up....

Hey, really nice blog. I have troubles understanding how the projected area for a cylinder would look like. Doesn't it depend on how u cast a cylinder (standing or laying) hope u understand what I mean. Would be great if u could help me with the projected area for a cylinder

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here you would find a list for clamping force vs shot weight:,though each injection molding factory has its size,but the difference is acceptable on the list,and you need check by yourself,

Injection molding machines are usually characterized by the tonnage of the clamping force that they provide.
plastic injection molding \Plastic Injection Molding Company 

How to calculate the pressure generated in injection molded part?

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