Compression Molding Presses 101: An Ultimate Guide for Beginners & Experts

Compression press is a machine that compresses and shapes materials into suitable shapes and form.

You can use molding press to mold items like composites, fiberglass, sheets, guard hardware, and aviation components. The best part, you can make parts across many industries.

Type of Compression Molding Machines

Compression molding machines come in various types depending upon their design and capability. Some of the common types include:

1. Up-acting Compression Molding Presses

These are designed to shape materials by moving the press table vertical. This design applies viable pressure force from the top, making it flexible for applications like trim composite materials, thermosetting plastics, and other molding processes.

The upward pressure applied effectively gets the oil far from any hot surfaces, consequently protecting sensitive parts against contamination. These machines are usually known for their flexibility, ability to yield high quality molded items and safety attributes. They find application across different areas including electronics, automotive, aerospace, and assembling.

2. Down-acting Compression Molding Presses

These molding presses work with a vertical downward movement of the press table during compression. This allows for productive trim and molding of different materials like composites and thermosetting plastics. Additionally, they are highly recognized for their precision, dependability and ability to make high quality molded items.

They are often used in enterprises such as aerospace, electronics, automotive manufacturing among others.

3. Multi-Opening Presses

These are machines utilized in industries to press many parts at once. They have various openings or stations, and that implies they can deal with several pieces simultaneously, making creation quicker and more proficient.

Multi-opening presses are presented in various setups, including pneumatic, mechanical designs and hydraulics, to suit explicit application needs. These presses are regularly utilized in busy industries where there’s a need to rapidly create numerous products.

They likewise streamline activities by handling different tasks in a single machine, saving space and expanding proficiency.

4. Compression Molding Lab Presses

These presses are frequently smaller than industrial scale versions and are explicitly custom-made for research, development, and testing applications. They provide a quiet operation, minimal bed sizes, and adjustable control choices that are vital for Research and development conditions.

Compression molding lab presses work on the same principle as the large industrial presses, utilizing pressure and heat to shape materials like rubber and plastics. They assist specialists and designers to study materials, innovate new items and improving manufacturing process.

How Hydraulic Compression Molding Press Works

Hydraulic compression molding presses works by utilizing hydraulic pressure to compress materials between two warm platens. It entails the following steps;

· Step 1: Preparation of Material

This incorporates cleaning, cutting, and preheating raw materials to ensure they are free from contamination and reasonable in size for feeding. In some instances cases, synthetic compounds like benzoyl peroxide might be added if necessary to improve the bonding mechanism during the curing stage.

· Step 2: Preparation of Mold

It involves warming mold to the right temperature for the material. Then, it is greased so that the material won’t adhere to it.

· Step 3: Material Loading

Once the mold is ready, an exact amount of pre-warmed material is set into the mold cavity. This precise amount ensures that the cavity is sufficiently filled without any surplus material.

· Step 4: Compression Molding

The machine brings the two mold parts together, applying tension with press brakes or platens. This process fills the cavity with material, pushing out any abundance. Whether heat is applied to the press platens relies upon the machine type.

· Step 5: Curing Process

Here, the material goes through a reaction that changes it from flexible state to rigid state. The pressure is maintained until the material solidifies and takes the shape of the mold cavity. Curing agents such as benzoyl peroxide can also be used to speed up the cross-linking reaction during the process.

· Step 6: Cooling

Following the curing process, the temperature of the mold continuously starts to decline. Cooling can be accomplished by either permitting the heated mold to naturally cool or utilizing strategies, for example, air or water cooling.

· Step 7: Opening of Mold and Part Ejection

Molds are opened by using control arms that are associated with the mold halves, and part ejection is done by utilizing an ejector framework, which contains plates or pins. This step involves ejecting the completed part from the mold.

Ultimately, the formed parts go through trimming and finishing to upgrade their quality and ensure compliance with specifications.

Compression Molding Machine Specifications

Compression molding machines comes in various specifications depending on the brand and the model. Some of the typical specifications include:

· Tonnage

The tonnage for a high capacity press ranges from 150 to 2500 tons, dependent upon the application requirements and the specific model available. But it can sometimes go as low as 100 tons especially for down-acting compression molding presses.

Machines with higher tonnage capacities are capable for applying greater force during the molding; therefore, they come with higher price tag.

· Bed Size

Typically, the size of the bed is defined by the dimensions of the machine that the machine can deal with. The bed size of compression molding machines varies, going from small tabletop units with beds estimating a few square inches to enormous industrial machines with beds surpassing several square feet.

The size of the bed has an impact on the overall price of the machine. Larger bed size tend to increase the cost of the machine since it requires more materials and engineering to manufacture. However, even a smaller bed size may also be costly if they integrate advanced technologies and features.

· Pressing Speed

This speed ranges from 15 to 25 mm/sec. However,  the pressing speed is determined by various variables such as the material being molded, the complexity of the component, and the ideal nature of the final product.

· Working Pressure and Temperature

Mold are usually heated at a temperature of 350F (or 180 °C) while being exposed to a pressure of approximately 100 psi (or 700 KPa) for a curing period of roughly 3 minutes.

· Mold Size

Compression molds have the ability to produce parts across an expansive range of sizes. These part sizes can range from as small as 0.024 inches to as large as 30 inches in diameter. Machines with large mold size are more complex, larger in size and require more power. This makes the have a higher price tag compared to machines with small mold size.

Applications of Compression Molding Machine

Compression molding machines are generally involved across various industries for producing high quality parts using various materials. Some of the application areas include:

• In aerospace industries to produce components such as insulation panels, interior cabin parts and more.
• In packaging industry to create packaging materials such as containers, closure and bottle caps
• Automotive industry to produce vehicle parts such as gaskets, exterior body panels, engine components, interior trim panel among others.
• Medical components and equipment such as dental products, orthopedic supports etc.
• Electrical industry to produce electrical insulators, switchgear components and circuit breakers.
• In consumer goods such as sporting goods, kitchenware
• In construction industry to produce items such as decorating panels, roofing tiles

Conclusion

Compression molding machine remains as a flexible and cost- effective solution for satisfying the needs of robust part production across diverse sectors. Its capacity to deal with a large number of materials, including thermosets, thermoplastics, rubbers, and certain composites, makes it an important resource for producers working with little to medium volumes.

TSINFA CNC Equipment is your trusted compression mold press manufacturer in China – contact us today for high quality machines.