If your plant has different sizes or makes of machines, most likely they have different intensification ratios. This plastic pressure must be duplicated as you go from to machine to machine with the same mold. It is plastic pressure that pushes plastic into the sprue, runner, gate, and mold cavity, not hydraulic pressure. Today you can buy machines with intensification ratios ranging from 6:1 to 43:1. Most machines today are not 10:1 in intensification ratio.

Provides roughly 8000 psi (551.7 bar) of melt pressure inside the nozzle. That is, 800 psi (55 bar) psi of hydraulic pressure This is the machine’s intensification ratio and explains how several hundred psi of hydraulic pressure can provide thousands of psi plastic pressure inside the nozzle. Here, hydraulic pressure is intensified or multiplied by a factor of 10. This large-to-small ratio of ram areas intensifies or magnifies the hydraulic pressure as it is converted to plastic pressure in the injection nozzle. The non-return valve during injection forward acts as a smaller ram let’s use 15 cm2. The hydraulic ram has a large surface area let’s use 150 cm2 as an example. The large hydraulic ram pushes the screw, and the non-return valve (check valve) acts as a plunger pushing plastic through the nozzle into the mold. That is, force (F) is equal to pressure (P) multiplied by area (A). The law of physics involved is F = P × A. Molders need to understand that hydraulic power is converted (multiplied or intensified) into plastic pressure (melt pressure in the nozzle). Hydraulic machines, on the other hand, work with hydraulic power. Machine B had 29,200 psi (2014 bar)-some to spare. Machine A had only 20,000 psi (1380 bar)-not enough. The mold needed 23,000 psi (1585 bar) to fill. Turns out machine A had an intensification ratio of 10:1, and machine B was 14.6:1. This took some time as it was, and still is decades later, a hassle to find out exact hydraulic ram areas. Once I learned about intensification ratio, I went back to the shop and calculated them for machines A and B. the intensification ratio varied with different screw sizes. However, when I started out, it was at a time when some machine manufactures realized it was cheaper to buy stock hydraulic cylinders rather custom building a hydraulic cylinder to match each different screw for a 10:1 ratio. Why Knowing the Intensification Ratio Is Critical So for a while it did not matter if you used hydraulic pressure (a machine variable) or plastic pressure (a plastic variable) when moving a mold from one machine to another. Why? As it turns out, most early machines were made with a 10:1 ratio of hydraulic ram area to screw area (not diameter). If it went into Machine B, it was a good day. If the mold went into Machine A, I’d have problems.

During my early days of processing, I swore certain molds could read the name on the machine, and if they did not like it they just were not going to make acceptable parts.

Hydraulic ram pressure calculator