Laboratory Press: Complete Guide to Types, Applications & Selection
Contents
What Is a Laboratory Press?
A laboratory press is a miniature version of an industrial press. Lab press is a bench-top or floor-standing machine which primarily applies a progressively increasing compressive force to a material sample.
The force can shape the material. Prepare the material for testing or use it to craft patterns or study a material’s response to force.
Any laboratory press has three main components:
- Frame: resists the reaction force
- Platens: platens are plates or components that make contact with the sample or mold
- Force mechanism: how the force is generated, which depends on the hydraulic or motor press.
How Hydraulic Force Is Generated
The most common type of lab press is the hydraulic press, which works on a very simple pressure law. When pressure is applied to an incompressible fluid (oil), it is transmitted equally in all directions throughout the fluid.
In a lab press, a small pump piston is used to move the hydraulic fluid into a larger cylinder cavity. You can guess the force output at the ram will be higher because pressure is constant across the system, and the ram area is larger than the pump piston area.
This ratio can be adjusted by changing the size of the RAM, cylinder, or piston. For example, an area ratio of 10:1 means a 100 kg input force can turn into 1000 Kg at the ram.
The Press Cycle: How a Test or Molding Run Actually Works
The press cycle follows four stages:
- Setup: Mold or die is loaded between platens, and the press can be heated (this is optional). You set the target pressure.
- Pressing: Once you activate the pump, pressure increases and the platens close against the mold, and the result is a force built to the target value. Here, the difference between automatic and manual presses is also considerable. In a manual press, you need to watch gauges, but in an automatic press, a PLC controller can set the required force automatically.
- Dwell: This is the stage where pressure is maintained for some time. For rubber vulcanization, this time is usually when the crosslinks form, and for KBr pellet formation, this can be 30 seconds or more. The cycle counter records the number of holds (dwell).
- Release: as the name suggests, pressure is relieved, and the platens return to the open position,n and the die is removed. If the pressure is high, normally there’s a cooling stage before the mold opening.
Core Types of Laboratory Press
| Type | Tonnage Range | Heated Platens | Operation | Primary Use |
| Manual Hydraulic | 2 – 25 T | Optional | Manual pump | R&D, low volume QC |
| Automatic Hydraulic | 25 – 150 T | Optional | PLC / motor-driven | High-throughput QC |
| Heated Platen Press | 5 – 100 T | Integrated | Manual or auto | Rubber vulcanization, plastics molding |
| Pellet Press (KBr) | 2 – 15 T | None | Manual/handheld | FTIR / XRF sample prep |
Manual Hydraulic Laboratory Press
The manual hydraulic lab press uses a hand lever pump, which builds pressure. The machine is dependent on user inputs and controls through analog dials. It has no motor or electronic control and is a purely mechanical press.
The machine is limited to 25 tonnes press capacity and is unreliable in applications that require repeatability and controlled parameters. It is not recommended for cycle-to-cycle production.
Automatic Hydraulic Lab Press
Automatic lab presses like the FYI Laboratory Press use an electric motor-driven hydraulic unit. You can pre-set the load, dwell time, and program instructions into the lab press for a multi-step rubber lab press cycle. It has a PLC that controls the valve, which is used to maintain pressure or release pressure within a very tight pressure tolerance.
This removes variability and non-standard tests that would come from manual inputs and experimental variance. Autmotaic lab presses are the standard choice because they can be used by multiple operators and provide micro control over the parameters.
Pellet Press / KBr Press
Pellet presses are much smaller hydraulic presses that are specifically designed for the purpose of forming solid pellets from a powder. The most common use of these lab presses is to experiment or produce KBr discs for spectroscopy.
Heated Platen (Hot) Press
Heated platen or a heat press has an electric heating unit in the plate, which is thermally adjusted to apply heat and force to the rubber mold simultaneously. These types of lab presses are useful for thermoplastics, elastomers, and rubber materials.
The temperature is controlled and checked automatically using a PID controller, which can set and correct the temperature with an accuracy of up to 0.5°C. Water-cooled platens are also an option, but only needed when you need fast quenching rates post-molding, for example, for ASTM D4703 standards.
Applications of Laboratory Press
Sample Preparation for Spectroscopic Analysis
FTIR spectroscopy requires sample preparation, and the samples need to be thin, transparent discs. The standard method uses a mix of KBr powder and analyte in a die with a 1 – 2 minute dwell time.
Compression Molding of Rubber and Plastics
Compression molding is the process used for turning rubber or thermoplastic into a flat sheet or a geometry of your choice. There are many ways, some that require heat and pressure at the same time, or simply pressure.
The mold is loaded with the material, and heated plates press the rubber under a target pressure where it can take form, and the heat can start the vulcanization. FYI’s lab press is an ASTM and ISO certified solution for rubber and plastic pressing.
Materials Research
A laboratory hydraulic press can also be used for materials beyond rubber and plastics. For example, ceramics require powder materials to be die-pressed at ambient temperatures before final sintering.
Lab press of small tonnage is also useful for pharmaceutical laboratories to form compact tablet forms and study compression pressures and their effects on compactness and hardness of tablets.
Material Property Testing
Lab press can also be used for material research, specifically mechanical properties. Some mechanical tests require compression and pressing directly on the testing instrument. You can use a compressive press to retrieve load-deflection curves on elastomers or solid materials.
Polymer Development
Film formation and laminate screening are some of the most common tasks a heated laboratory press can assist you with. For example, it can produce experimental formulations with consistent thickness for optical or mechanical property screening. This is the function of the FYI Tester DW series because of its wide temperature range.
Critical Specifications to Understand Before Buying a Hydraulic Laboratory Press
Tonnage and Platen Size
There is a specified required force that needs to be exerted onto the mold to ensure a uniform force distribution and to properly test a sample. The force required depends on several factors, such as the material and the mold or die area.
This force is calculated through the formula: Force (T) = Pressure (MPa) × Area (cm²) ÷ 98.1
For reference, a 150 mm × 150 mm rubber mold requiring 10 MPa contact pressure requires approximately 23 tonnes of ram force.
The platen size must be larger than the mold or die to ensure proper contact between the platen face and the die, ensuring even force distribution on the mold. An undersized platen can produce unwanted results at the edges, with more force on the edges than in the center, resulting in higher edge density.
Heated vs. Unheated Platens
Heated platens depend on the requirement; if the majority of your process is being done at ambient temperature and the material does not have an explicit need for heat for processing, then heated platens only add to the cost.
If any process involves elastomers, polymers, and thermoplastics that need heat to manipulate, heated platens become a necessary component of the process. Platens whose lower and upper platens can be controlled separately allow for processes that require different cooling or curing temperatures.
Analog vs. Digital Pressure Gauge
Analog gauges give a direct reading from the hydraulic press through a bourdon tube that moves depending on the hydraulic pressure. Digital pressure transducers are connected to a display or PLC, which allows for further operation, such as data logging and control, including alarms and switches. Documentation usually prefers digital gauges since they allow better data collection.
Automatic Operation
Automatic operation is usually useful for high-cycle and repeatable processes. When multiple operators use the same press, automatic operation ensures the same consistent process, preventing errors. Manual presses with a reliable gauge deliver acceptable performance at lower cost and simpler maintenance for low-volume R&D.
Cooling Systems
Cooling is crucial for materials such as thermoplastics to ensure they solidify before taking them out of the mold. Options include water-cooled platens that have internal channels for even temperature control, and air-cooled systems work by blasting compressed air below the surface of the platen. Air-cooled systems have a lower cooling rate, typically 3–5°C/min, compared to 50°C/min for water cooling on some systems.
Cycle Repeatability
Repeatability is linked to the accuracy of the pressure gauge, pump consistency, and relief valve stability. Automatic presses with PLC-controlled relief valves hold force within ±1–2% of the setpoint across cycles. The cycle repeatability depends on the operators and is typically 3-5% of the setpoint value. Rubber specimens have to meet the ISO 2393, where the platen has to match a required value, which calls for an automatic control or at least a verified gauge for consistency.
Key Specifications of FYI Laboratory Press
FYI, Tester DW5150A and DW5150B are standard hydraulic presses that are designed for vulcanization of rubber, plastics, and chemical materials. Both of them have a dual high/low hydraulic circuit that works by using low pressure to move the platens to close the mold and then switch to high pressure for precision and high-pressure force hold. This approach extends the pump life and reduces cycle time compared to single-stage systems.
The pressing plates are made of chromium-molybdenum alloy steel with high-frequency hardened and surface polished to a 60 HRC, which is resistant to indentation and improves the life of the mold. To ensure thermal cracking isn’t an issue for the plate, it is made from a steel plate that supports even temperature distribution.
| Parameter | DW5150A | DW5150B |
| Max Pressing Force | 25 T (245 kN) | 50 T (490 kN) |
| Hot Plate Dimensions | 300 × 300 mm | 400 × 400 mm |
| Temperature Range | RT – 300°C | RT – 300°C |
| Temperature Controller | PID digital | PID digital |
| Pressure Gauge | Analog (hydraulic) | Analog (hydraulic) |
| Hydraulic System | Dual high/low pressure | Dual high/low pressure |
| Plate Material | SKD Cr-Mo alloy, 60 HRC | SKD Cr-Mo alloy, 60 HRC |
| Primary Application | Rubber, plastics, pigments | Rubber, plastics, composites |
Conclusion
The laboratory presses you choose depend on requirements such as force capacity, platen configuration, and control systems that align with the materials that you work with. A manual hydraulic press is useful for most general-purpose sample preparations, while an automatic heating press is crucial for applications that demand cycle repeatability and ISO standard compliance.
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