What is the VIP Vacuum Infusion Process? An Article Explains its Development and Application in Detail

 

Vacuum Infusion Process (VIP)

Among the current materials, composite materials are widely used because of their light weight and high strength. The manufacturing process for composite materials is also constantly improving and innovating.

From the initial hand lay-up, to mechanized spraying, drawing, molding and other processes, to the current vacuum infusion process, the processes related to vacuum infusion include resin transfer molding (RTM), vacuum assisted RTM (VARTM), vacuum bagging, SCRIMP, SRIM (Structural Reaction Injection Molding), RFI (resin film infusion). But there are some differences, which have been introduced in many articles, so I won’t go into details here.

Vacuum Infusion Process (VIP)

Vacuum infusion process (VIP) is to lay “dry” reinforcement materials (glass fiber, carbon fiber, sandwich materials, etc., which are different from vacuum bag process) on the mold, then lay vacuum bags, and extract the air in the system to form a negative pressure in the mold cavity.

 

The pressure generated by the vacuum is used to press the unsaturated resin into the fiber layer through the pre-laid pipeline, so that the resin can infiltrate the reinforcement material and finally fill the entire mold.

After the product is cured, the vacuum bag material is removed and the desired product is obtained from the mold. VIP uses a single-sided mold (like the usual hand lay-up and injection mold) to establish a closed system.

The vacuum infusion process has been public for a long time, and the process has been patented in 1950.

However, it has not been developed until recent years. Since this process was introduced from abroad, it has many names, such as vacuum infusion, vacuum infusion, and vacuum injection.

 

Theory

The vacuum infusion process can be widely used, and there is a theoretical basis, which is Darcy’s Law:

 

 

 

Advantages

In the usual hand lay-up process, the reinforcement material is spread in the mold and manually impregnated with a brush, a spoke or other means.

Another improved method is to use a vacuum bag to suck out the excess resin in the hand lay-up layer. This increases the glass fiber content and obtains a higher strength and lighter product. VIP has many advantages over traditional processes.

As shown in the figure, hand lay-up, vacuum bag and vacuum infusion are used as examples. Vacuum infusion has obvious advantages in mechanical properties.

 

 

From this We can See the Advantages of Vacuum Introduction

 

Higher Quality Products:

In a vacuum environment, the resin impregnates the glass fiber, and there are very few bubbles in the product compared to traditional manufacturing processes.

There is no excess resin left in the system, and the glass fiber content is very high, which can reach 70% or even lower. The resulting product is lighter and stronger. It is also very stable from batch to batch.

 

Less Resin Loss:

With the VIP process, the amount of resin can be accurately estimated. For hand lay-up or injection processes, it will be difficult to control due to the variability of operators. VIP can minimize the loss of resin, and more importantly, it can save costs.

 

Uniform Distribution of Resin:

For a product, the pressure generated by the vacuum in different parts is consistent, so the resin impregnation speed and content of the glass fiber tend to be consistent. This is very critical for FRP parts with stable weight requirements.

 

Less Process Volatility:

There are no brushes or spokes in the production process, which will not cause the resin to be splashed or dripped, and there will be no large amount of odor. Therefore, it can provide a clean, safe and friendly working environment to protect the physical and mental health of the operator.

 

Use Single-Sided Mold:

Only one side of the mold can be used to obtain products with smooth and flat surfaces on both sides, and the thickness of the product can be better controlled. Save mold manufacturing costs and time.

Because the products made with VIP technology have such advantages, they were first used in special fields such as aerospace, and later gradually applied to high-demand civilian products.

 

Application fields of VIP technology

 

1) Boat industry-hull, deck, rudder, radar shield…

 

2) Wind power energy-blades, engine room cover…

 

3) Sports and leisure-helmets, sailboards…

 

4)) Automobile industry-all kinds of roofs, windshields, carriages…

 

5) Construction field-building top parts, building templates…

 

6) Agriculture and horticulture-grain silo round cover, agricultural machinery protection cover…