Auxiliary demolding cylinder play a vital role in hydraulic press machine, its role is to provide additional, controllable force to ensure that the mold can be more smooth, smooth, completely open, and reduce the noise of the opening of the mold after the main cylinder to complete the press/closing action and return. So, what materials do you need to add auxiliary demolding cylinder when pressing with the machine ?
Materials that have high shrinkage or tend to "hug" the core/cavity
Rubber (especially soft rubber, silicone rubber)
This is the most typical requirement. Rubber is very elastic, shrinks after vulcanization and tightly wraps around the raised part of the mold (core), creating a strong clamping force and vacuum suction. This cannot usually be overcome by the return force of the master cylinder alone, and must rely on the auxiliary mold-opening cylinder to provide a strong initial mold-opening force.
Certain thermoplastics (TPE, TPU, soft PVC, LDPE, etc.)
These materials are soft, elastic, and have a relatively high shrinkage rate, which makes it easy to shrink and tighten the core after cooling, especially for deep cavities, thin-walled, or products with inverted buckles.
Thermosetting plastics (such as phenolic resins, epoxy resins, unsaturated polyester / BMC)
shrinkage in the mold during curing, and may produce strong adhesion with the mold surface (especially when the mold surface finish or the use of release agents improper), requiring additional mold opening force.
Foam (EVA, PU, etc.)
The foaming process fills all corners of the mold cavity, and after cooling and curing, it has a large contact area with the mold surface, which is prone to adsorption and encapsulation.
Materials that are sticky or tend to adhere to the mold
- Insufficiently vulcanized / cured rubber or thermosetting plastics: If the timing of demolding is a little early or formulation problems, the material may still be in a viscous flow state, adhering to the mold.
- Materials containing high viscosity plasticizers or oils: such as some soft PVC, oil-containing rubber formulations, oils may seep out to increase viscosity.
- Certain engineering plastics (e.g., PC, PA) under certain conditions: If the mold temperature is too high or insufficient cooling, it may also produce temporary adhesion to the mold.
- Adhesives, sealants: have a strong viscosity in the molding itself.
Powder metallurgy materials
Metal powders (iron based, copper based, etc.): When pressed and molded under high pressure, the powder particles are embedded in tiny pores on the surface of the mold (even if the mold is very hard), generating a great mechanical bite and friction. Very high forces are required for demolding (mold opening) and auxiliary demolding cylinder are almost standard. The higher the pressing pressure, the higher the density of the blank and the larger the side area, the higher the mold opening force required.
Materials and structures that are prone to "vacuum adsorption"
Large-area, thin-walled products
Whether the material is plastic or sheet metal (such as after stamping), when the product surface is smooth and flat and close to the mold, the moment of mold opening between the product and the mold is easy to form a local vacuum (negative pressure), resulting in a strong adsorption force. Rubber, soft plastics, especially obvious, but hard materials in large thin-walled parts will also be encountered.
Deep Cavity Products
Similar to large thin-walled, deep cavities are also susceptible to vacuum formation when the mold is opened, requiring additional force to overcome.
Use of complex mold structures (indirectly related to the material)
Molds with deep cores, inverted buckles (requiring side core extraction) or small projections:
These structures significantly increase the resistance of the part to be released (opened), even if the material itself does not have a high shrinkage rate. An auxiliary mold opening cylinder ensures reliable initial mold opening action, creating conditions for subsequent ejection or side core extraction.
Multi-cavity molds:
The total mold opening force requirement is greater, and the auxiliary mold opening cylinder can provide stable and reliable mold opening force.
Large and heavy molds:
The weight and friction of the mold itself are very large, the return force of the master cylinder may not be enough to start the mold opening smoothly, and the auxiliary cylinder is needed to help.
Recently, the Shanghai ANTISHICNC team received a request for quotation from a customer who would like to press composite materials with a hydraulic press machine. The customer requires a machine with a working table size of 2000*1500mm and a keep press function. According to the customer's specific requirements, we recommended 1000 tons four column Hydraulic press.
The 1000-ton four-column hydraulic press machine adopts three-beam and four-column structure, equipped with auxiliary demolding cylinder, backup hydraulic circuit (for core pulling) and PLC function. It is suitable for pressing process of various plasticized materials, such as stamping, bending, flanging, stretching of thin plate parts, forming, punching, bending, and so on. It can also be engaged in calibration, press fitting, wheel molding, plastic products and powder products press molding.
| Description | YQ32-1000T |
Maximum liquid pressure (Mpa) | 25 |
Slider stroke (mm) | 1000 |
Maximum opening height (mm) | 1500 |
Table size (mm) | 2000*1500 |
Down speed of empty range (mm/s) | 120 |
Working speed (mm/s) | 6-12 |
Return speed (mm/s) | 110 |
Motor power (kw) | 30*2 |
Oil pump displacement (ml/R) | 125*2 |
Remark: The above parameters are for reference only, the actual parameters of the machine please refer to the technical program of Shanghai ANTISHICNC.
If you have composite material processing needs too, welcome to consult Shanghai ANTS Machine Equipment co., ltd. We have rich experience in manufacturing and using hydraulic press machine machine and can provide you with professional technical support.
