Tie bar load calculation in the die casting process, the tie rod is a key connecting component between the die casting machine and the mold.
And it is directly related to the safety of the equipment and the quality of the casting.
The function and structural characteristics of the tie rod
The tie rod (also known as the Colin column) of the die-casting machine is mainly used to bear the clamping force.
To ensure that the mold remains rigidly closed during the high-pressure filling process.
The number is usually 4, and it is symmetrically distributed at the four corners of the die casting machine template to form a closed frame structure.
Tie rod structure parameters
Diameter: 70mm (100T small machine) to 180mm (800T large machine).
Spacing: For example, the inner spacing of the tie rod of J1115 die-casting machine is 420×420mm, while the SJ800 type is 910×910mm.
Material: Usually made of high-quality alloy steel (such as 42CrMo4), quenched and tempered (QT process), the yield strength ≥ 500MPa, and the tensile strength ≥700MPa.
Detailed explanation of the load calculation of Tie Bar in die-casting
Tie rod is the core component of the die casting machine’s clamping device, which mainly plays the following roles:
Connecting template
Through four tie rods, the fixed platen, the moving template and the frame are connected into a rigid structure.
Withstanding Expansion Force
During the injection process, the molten metal is injected into the cavity at a high pressure (typically 400-800 bar).
And the resulting Opening Force is counteracted by the tensile stress of the tie rod.
Maintain mold clamping accuracy
The stiffness of the tie rod directly affects the closing stability of the mold parting surface.
And uneven load will lead to flash, mold deformation and other problems.
The core formula of tie rod load calculation
The load of tie rod is directly related to the clamping force.
And the calculation formula needs to comprehensively consider the following parameters.
Total projection area (A)
The area of the sprue system is usually 15%-30% of the projection area of the casting, and the area of the overflow system is 10%-20%.
Filling pressure (p)
In aluminum alloy die-casting, the filling pressure is selected according to the application.
Appearance parts: 500-600 kg/cm²
Non-sand hole parts: 600-800 kg/cm² Pressure-resistant parts: 800-1000 kg/cm²
Clamping force (F)
The compensation coefficient K is taken as 1.2-1.4 to cover dynamic shocks and load fluctuations.
If the casting has a projection area of 2000 cm², a sprue area of 20% (400 cm²), an overflow area of 15% (300 cm²).
And a filling pressure of 600 bar, the total clamping force is: A die-casting machine with a clamping force of ≥ 2106 tons is required.
Key Influencing Factors and Optimization Strategies
Pressure Distribution Characteristics
During the die-casting process, the pressure decays from the inner gate outward, resulting in uneven force on the mold.
Optimizing the gating system with mold flow analysis (e.g. MAGMAsoft) reduces the risk of local overloads.
Thermal expansion compensation
The mold temperature rise (usually 200-300°C) will cause the tie rod to elongate,
The design reserves an expansion gap (0.2-0.5mm) and uses a prestressed structure to offset thermal deformation.
Material & Process Matching recommends 42CrMo4 QT or H13 steel.
With surface nitriding treatment (hardness≥60HRC) to improve wear resistance and fatigue resistance.
Design Specifications & Standards
Material Standards
Tie rod thread conforms to GJB 3.1, hardened with 28-32 HRC after quenching and tempering, and impact power ≥ 40 J.
Inspection Requirements
Ultrasonic flaw detection for internal defects, magnetic particle for surface cracks (per ASTM E1444).
Installation tolerance
The length difference between the four tie rods is ≤0.05 mm/m, and the preload deviation is ≤3%.
Cutting-edge technology development
Intelligent clamping system
Adjust the tie rod nut in real time through a built-in sensor to compensate for the loss of preload caused by thermal expansion.
Such as the closed-loop control of the Lanson LS1300 die casting machine.
Structural innovation
Guangdong Baoyang EM-K series adopts a rigid tie-rod injection system, and the coaxiality error is ≤ 0.02 mm, which reduces the risk of eccentricity.
