Using a silicone membrane to impregnate parts with resin is an intermediate stage between manual moulding and vacuum infusion or RTM. The resin saturates the package of the reinforcement materials previously installed within the tooling in a vacuum and using a hermetically sealed flexible membrane.
Using silicone, a disposable vacuum film bag can be replaced with a reusable bag. Similar to the RTM process, the membrane plays the role of a flexible puncher that reflects the shape of the tooling at the distance of the required thickness.
The membrane helps save significant time and materials. The resin feeding methods vary depending on the part size and the complexity of the shape.
The membrane is especially efficient for making a large number of large structures, as the price of the tooling is relatively low. Unlike the RTM process, in the case of a membrane, the surface quality is lower, but the laminate properties and resin-to-glass mat ratio can be excellent.
Examples of application:
1. mass production of automotive transport and agricultural machinery parts 2. boat hull elements 3. elements of advertising structures and outdoor decoration
Main suppliers:
Basic materials:
DISTITRON
1402
Low viscosity orthophthalic pre-accelerated resin. Gel formation time 25-32 minutes.
POLYCOR
ISO
Isophthalic gelcoat for spraying and brush application. Supplied in any RAL colour. Intended for use in open air.
EMCL
PP180
Three-layer glass mat with a density of 300, 450, 600 g/sqm and polypropylene core with a density of 180 g/sqm. It is well draped. High speed of impregnation.
MARBOCOTE
220
Semi-permanent release agent for polyester resins. This compound ensures the high gloss of the surface with little effort. It is also very strong, which guarantees many extractions.
Equipment
and
consumables
Mixing and injection equipment, silicone application equipment.
Advantages of the technique:
1. faster production cycle, increased turnover of tooling 2. environmentally friendly, little waste 3. reproducible and low labour cost
Disadvantages of the technique:
1. limited physical and mechanical properties of the materials because it is difficult to insert additional reinforcement 2. higher requirements for workforce skills
