Hydraulic presses for elastomer processing in cleanrooms are used in particular for the production of closure systems for pharmaceutical packaging, in the manufacture of bipolar plates, and in the semiconductor industry.
Very high standards are set for their precision, the consistency of processing temperatures, and the documentation of process data. The systems are typically space-optimized, integrated into cleanrooms, and operated either semi-automatically or fully automatically, depending on the specific requirements.
A key feature is the seamless integration of the machine enclosure into the cleanroom design, which prevents contamination from the maintenance area, known as the “gray room.” It is important that, regardless of the operating mode or level of automation, all system components remain accessible to personnel at all times—not least for maintenance and service.
Marc Jordan, Vertrieb Wickert Maschinenbau GmbH, Landau/Pfalz,
E-Mail: m.jordan@wickert-presstech.de, Telefon: +49 6341-9343-60
Marc Jordan is the contact person at Wickert Maschinenbau GmbH for pharmaceutical presses used to manufacture packaging components from elastomers. He began his career at the Palatinate-based machine manufacturer in 2008 as deputy purchasing manager; he later took over sales of hydraulic presses for fixture and press hardening. Since 2021, his work has focused on elastomer processing—including in cleanrooms.
When manufacturing elastomer products in a cleanroom, hydraulic presses must meet a range of requirements regarding precision, temperature uniformity, compliance with standards, and process monitoring. A low particle load in accordance with ISO 14644-1 classifications is achieved primarily through comprehensive automation of production, easily cleanable machine rooms, the extensive elimination of lubricants, and encapsulated machine components.
In addition, it is necessary to monitor and document process data to ensure consistently high process and product quality and to meet regulatory requirements.
As a rule, hydraulic presses are designed and manufactured as special machines or in very small quantities according to customer-specific requirements. Due to their modular design, they can be configured in numerous variants. Processing temperatures of up to 500 °C and pressing forces between 20 and 100,000 kN are just as possible as flatness parallelism of up to 0.025 mm/m.
The hydraulic systems responsible for building up pressure are highly precise, fast-responding and energy-efficient. They can be parameterized in a variety of ways and guarantee a constant and reproducible process.
Among the innovative technologies are magnetic clamping systems and vacuum technology, which ensure a uniform temperature distribution and a precise venting process. They enable homogeneous molded parts and consistent process quality.
The dimensions of the presses and their precision heating platens, with an extremely homogeneous temperature distribution, can be freely selected. A wide range of automation and networking options, as well as the integration of further manufacturing processes, ensure high productivity and versatility of application.
Producers from the pharmaceutical industry and medical technology are among the main customers for hydraulic presses used in production in clean and ultra-clean rooms up to Class 6 in accordance with ISO 14644 (Photo 1).
Cleanroom hydraulic presses are used, for example, in the production of pharmaceutical closure systems made from butyl rubber (IIR) and bromobutyl rubber (BIIR). Sealing films for bipolar plates made from elastomers and valve membranes for the chemical and medical industry made from chemical-resistant polytetrafluoroethylene (PTFE) are also manufactured on them. Rubber-metal composites for semiconductor manufacturing are likewise produced on hydraulic presses in cleanrooms.
Since rubber compounds used in the pharmaceutical sector in particular are highly prone to the formation of air inclusions, the vulcanization process on cleanroom presses takes place in an airless environment, in vacuum chambers. This is because the negative pressure of up to -990 mbar that prevails there initiates a very safe and controlled vulcanization process. Since air inclusions are avoided in this way, the raw rubber is processed in a material-optimized manner – which reduces rejects and costs, particularly in the case of expensive compounds.
A key quality criterion for the processing of elastomers in cleanrooms is the uniform temperature distribution within the pressing tool. The tolerances should be less than ± 1 °C, for example at typical processing temperatures of up to 230 °C. Even minimal deviations can affect vulcanization and lead to varying product qualities. The very precise temperature control ensures that the manufactured articles are very dimensionally accurate – even when using large tools.
Modern hydraulic presses address this challenge through innovative multi-zone controls and closed-loop systems that continuously monitor and compensate for temperature. These technologies ensure that every component, regardless of the cavity, is manufactured under the same conditions.
In addition to temperature, the parallelism of the press platens plays an essential role. Only with precise alignment of the platens can the required specific pressing pressure be transferred uniformly to all molded parts. This prevents dimensional deviations and uneven degrees of vulcanization.
To ensure the highest flatness parallelism with accuracies of up to one twenty-fifth of a millimeter per meter, not only is the utmost attention paid to the solidity of the supporting structure of a press. Only precision machine tools are used when machining the machine components employed.
For the supporting columns, which are thermally prestressed, only tempered bar stock from the same batch is used. Towards the pressure platens, they offer enlarged contact surfaces and shoulder supports to ensure a secure connection.
In cleanroom environments, space is a scarce and expensive commodity. Space-optimized systems such as double-deck presses, in which two press levels are arranged one above the other, make efficient use of the limited space available. Such a design increases production capacity without requiring more floor space. The decoupling of the hydraulic unit from the press frame also contributes to optimal space utilization; in addition, it minimizes noise emissions and vibrations during operation.
Presses in cleanrooms can be fully encapsulated; the housing is made of stainless steel sheet and all surfaces in the interior are designed to be easy to clean (Photos 2 and 3). To minimize contamination and prevent dirt particles from entering the mold area of the press, the enclosure is also connected to the press up to the upper pressure platen. All cables and media feeds are located outside the housing and are routed into the machine via bulkhead connections. In this way, an effective separation of the maintenance and production areas is achieved under cleanroom conditions.
It is important that machines for automated processes remain as accessible as for manual operation. While technical units such as hydraulic pumps, control cabinets and control systems are housed in the grey room at the rear of the press, the cleanroom itself is reserved for product-relevant manufacturing. These measures minimize contact between operating personnel and the product, which considerably reduces the risk of particle contamination.
The strict spatial separation enables effective control of the particle load. It also helps to minimize the space required in the cleanroom. At the same time, it facilitates servicing and maintenance of the machines without the associated interventions affecting production.
Fixed pipework offers clear advantages over conventional hose connections. It reduces vibrations and is permanently leak-tight, which improves cleanliness and minimizes the risk of leaks.
In addition, it does not need to be renewed regularly. This is because the replacement required every six years for hoses is eliminated, which reduces operating costs and increases machine availability.
The extended service life of the components also contributes to sustainability, as the need for replacement is considerably reduced.
The control of air flows plays a decisive role in the seamless integration of hydraulic presses into clean environments. They ensure that the particle load in the cleanroom remains below the desired limit values. Technologies such as Clean Air Modules (CAM) or Filter Fan Units (FFU) are used for this purpose, directing particle-free air into the work area. Automatic safety doors enable the application of release agents in the press room, thus preventing the aerosol from mixing and swirling with the atmosphere in the cleanroom. An integrated extraction system removes the particles remaining in the air.
Nevertheless, the machine enclosures are designed to provide easy accessibility despite encapsulation. This is just as important for mold changes, which generally take place from the grey room, as it is for predictive maintenance activities.
A flexible operating concept with mirrored human-machine interfaces (HMI) on both the grey room and cleanroom sides also reduces particle ingress. The additional control panel in the grey room at the rear of the press enables set-up personnel to prepare the press after a mold change – without having to enter the cleanroom. This allows them to simply bring tools to the rear of the machine, position them on the press table and clamp them. Additional staff to operate the machine from the cleanroom side are therefore not required.
Operating errors are prevented by the fact that both HMIs are interlocked with each other and can only be operated from one side.
Machine enclosures in cleanroom systems play a central role in minimizing the particle load. One possible source of contamination is painted surfaces, which tend to emit particles under the influence of heat and in reaction with release agents. To prevent this, the interior of pharmaceutical presses is made entirely of heat-treated surfaces, in particular stainless steel or aluminum alloy materials. They do not corrode, do not emit particles and are resistant to aggressive release agents.
Smooth and rounded inner surfaces of presses prevent particles from accumulating. The surfaces can also be cleaned easily. A self-supporting enclosure, also made of stainless steel, surrounds the working area of the press.
Another potential source of contamination is the auxiliary and lubricating materials used in presses. Material pairings that do not require lubrication with auxiliary materials are preferred. Where auxiliary and lubricating materials are necessary, only non-toxic and physiologically safe materials are used.
Moving parts of the machines are carefully encapsulated to prevent the escape of lubricants or auxiliary materials.
Systems that operate without lubricants are also used when clamping tools.
Since humans are one of the most important causes of contamination, automation of manual tasks is used to reduce this influencing factor. According to estimates, around half of all new systems are now at least partially automated.
In addition to replacing operating personnel, five factors in particular are decisive for automation:
The automation of hydraulic presses in cleanrooms brings considerable advantages. First and foremost, it increases the utilization rate, reduces cycle times and enables reproducible processes at all times, as the influence of human operation is largely reduced.
A further advantage is the reduced particle load, as human contact with the products is minimized, which reduces the risk of contamination.
The advantage of automation lies in precise and continuous process monitoring. Modern systems use quality controls based on Key Performance Indicators (KPIs) and quality gates to ensure that faulty process parameters are detected at an early stage – before the system implements them.
This means that incorrectly manufactured products cannot be produced in the first place, as the system control will previously report the violation of a specified production tolerance limit. All relevant parameters are documented in a tamper-proof manner, which complies with Good Manufacturing Practice (GMP) regulations. The input and creation of component recipes are managed via an access level matrix, so that only authorized personnel can make changes to machine data.
The degree of automation that makes sense in individual cases depends on various factors. The gradations range from classically manual to fully automatic. In any case, the individual requirements depend on the complexity of the product.
Loading and unloading systems improve the material flow between different production steps before and after pressing. Coordinated load carriers make manual loading and unloading unnecessary. In addition to reducing the handling effort for operators, this also reduces human contact with the product.
In cleanroom systems, linear systems in particular offer a space-saving solution for the feeding and removal of parts. Compared to robots, they are easier to operate and adapt when programs are changed. Their space-saving design also means that the machine room is easier to see into and access, which is an advantage should the feed system ever fail. There is therefore always an uncompromising backup strategy. A consistently modular system design, on which the control system is also based, contributes to this.
The total cycle time in production consists of the heating time and the open time of the press. Automated processes offer a number of advantages, as they enable, for example, the simultaneous loading of double-deck presses. Manual processes, on the other hand, require a sequential process, which noticeably extends the machine time. Manufacturing on two levels also has the positive effect that both press rooms are heated with the same heating time and the compound experiences identical process times.
By accelerating cycle times, production capacities are increased. At the same time, personnel requirements are reduced, which is particularly advantageous in times of a shortage of skilled workers.
Magnetic clamping plates enable the rapid changeover and fully automatic clamping of ferromagnetic tools of all sizes and geometries within a few minutes – without hydraulics and without manual intervention (Photo 4).
Operation and safety monitoring are completely integrated into the machine control system. When clamping and releasing, a current pulse activates the permanent magnets, which then operate independently of the current during operation – i.e. fail-safe. In this way, almost all tools can be clamped over their full surface area and with high bending stiffness, and later released again.
Although there are also magnetic clamping plates without integrated heating, models designed for temperatures of up to 240 °C are generally used in elastomer processing. The full-surface contact between the heating surface and the tool plate ensures that heat is transferred evenly and homogeneously. This technology thus indirectly supports uniform heat transfer into the tool. The clamping systems can be custom-manufactured according to the respective requirements in terms of size, geometry, clamping force and equipment.
They are virtually maintenance-free, can also be used in vacuum presses and can be retrofitted to existing machines.
The precise application of release agents is an essential factor in the processing of elastomers. If too large a quantity is applied, molded parts cool down or the surface properties of the product are impaired; if too little is applied, the finished part is difficult to demold. A reproducible and consistently uniform application of release agents therefore has a direct influence on product quality (Photo 5).
The optimal quantity and uniform distribution of release agents thus help to reduce temperature fluctuations and improve the stability of the production process. Particularly in the case of complex or filigree component surfaces, uniform coating is crucial to avoid rejects.
The automatic spray system is of compact design; the control and regulating elements are located outside the press housing in the grey room. During a tool change, the unit moves to a parking position.
The release agent is applied in the machine room with the stroke field closed; aerosols in the air are immediately extracted. In this way, contamination of the cleanroom atmosphere is prevented.
However, the possibilities for automation are far from exhausted. If desired, presses can be comprehensively equipped with sensors and actuators. This enables them to collect a wide range of information. This includes information on actual machine wear for predictive maintenance as well as data on production and processes and the quality of workpieces.
Automation within the framework of a smart factory concept is even more comprehensive. This envisages the intelligent networking of hydraulic presses and the associated peripheral components with other system participants and higher-level process control systems.
Hydraulic presses are designed for a long service life. During this time, changing production requirements sometimes require adaptations. Retrofitting offers a cost-efficient alternative to purchasing new equipment by equipping existing systems with new control technologies or automation solutions. Loading and unloading systems, magnetic clamping plates and controls are particularly frequently retrofitted.
The modernization of existing systems enables companies to respond to changing market requirements without having to make high investments in new machines. This approach is not only economical, but also sustainable.
Hydraulic presses for cleanrooms combine innovative technologies with precise process control and make them indispensable for applications in the pharmaceutical industry, semiconductor manufacturing and other industries with high cleanliness requirements.
Future developments in AI-supported process monitoring and energy efficiency will further improve the performance of these technologies.
In terms of automation, demand is expected to continue to rise in the coming years. Innovative technologies are making it increasingly economical even for smaller batch sizes; in addition, the growing number of component variants is reinforcing the desire for greater production flexibility. The shortage of skilled workers and rising personnel costs are also reinforcing the trend towards (partially) unmanned production. Through their continuous further development, hydraulic presses will continue to play a key role in elastomer processing in the future.
