Why do injection molding machines have different tonnages?

The cost of failed selection

Insufficient tonnage: product flash and size deviation (a mold that is stretched 0.1mm can lead to scrapping)

Tonnage is too large: energy consumption increases by 30%-50%, the risk of mold deformation increases, and mold exhaust difficulties lead to burning

Four-step scientific selection method

Calculate clamping force

Take the car bumper as an example: the projected area is 1200×600mm=7200cm², and the pressure in the PC mold is 400kg/cm²

Theoretical clamping force = 7200×400×1.2/1000≈3456T → Select the 3500T model

Test tolerance

Mold size ≤ tie rod spacing (such as the tie rod spacing of the 1000T machine is usually 1200×1200mm)

Mold thickness ∈ [minimum mold thickness, maximum mold thickness] (for example: the mold thickness range of 350T machine is 150-450mm)

Ensure demoulding space

Mold opening stroke needs to be > product height×2 + runner length (deep cavity parts need to add an additional 20% margin)

Match injection system

Finished product weight should be ≤ Theoretical shot volume × 75% (leave a safety margin)

For thin-walled parts, choose a small screw (high pressure and high speed), and for thick-walled parts, choose a large screw (high plasticizing capacity)

Industry scenario application

Electronic industry (below 100T): Connectors use a 30mm diameter screw, and the shot speed ≥300mm/s ensures filling

Home appliance industry (300-800T): Air-conditioning panels use hot runner molds + 650T machines to reduce runner waste

Automotive industry (>1000T): Door panels use a double-station turntable three-color machine to achieve one-time molding of substrate + soft glue + logo

Medical industry (50T fully electric): Syringe production is equipped with a Class 100 clean room to avoid hydraulic oil pollution

The selection of injection molding machine tonnage is undergoing three major technological changes:

Energy-saving drive

All-electric injection molding machines (such as FANUC Roboshot) replace hydraulic presses below 100T, reducing energy consumption by 60%; the penetration rate of hybrid technology in large machines increases (such as Haitian MA series)

Intelligent control system

IoT module monitors clamping parallelism in real time (deviation of >1000T machine needs to be ≤0.1mm/m)

AI algorithm dynamically optimizes the pressure holding curve, reducing the molding cycle of large-tonnage machines by 15%

Specialized development

Micro injection molding machine (<10T): used for medical microfluidic chips, injection accuracy ±0.002g

Multi-component large machine: such as Fuqiangxin FB-1900R three-color machine, turntable diameter 2250mm, serving the integrated molding of automobile lampshades

In the future, with the application of new materials (such as carbon fiber reinforced plastics), the clamping accuracy requirements for high-tonnage machines will be further improved, and modular design will make tonnage adjustment more flexible-by replacing the screw assembly, the same clamping unit can cover the injection range of ±30%.

The selection of injection molding machine tonnage is like deploying troops for a battle: too little will not be enough, and too much will be a waste of money and effort. From a connector the size of a fingernail to a car bumper several meters long, the difference in tonnage is the result of the deep collaboration of material science, mechanical design, and control algorithms. In the future, with the advancement of energy-saving technology and intelligence, tonnage selection will no longer be based solely on empirical formulas, but will be dynamically optimized based on real-time data, pushing plastic molding into a new era of "tailor-made".