Technology

CNC Filament Winding is one of the most important processes in composite processing technology.

Basic filament winding machines have two axes of motion, the mandrel rotation and the carriage travel.

For the manufacture of pipes, two axes machines are sufficient.

For pressure vessels such as LPG or CNG containers, it is advisable to have a four axis winding machine. In addition to the

1. Mandrel rotation axis
2. Carriage travel axis

There is also the additional axes, such as

1. Radial cross feed axis
2. Rotating fibre payout head

The payout head rotation can be used to stop the fibre band twisting and thus ensuring consistency of bandwidth during winding.

Machines with more than four axes can be used for advanced applications, six-axis winding machines usually have 3 linear and 3 rotation axes.

Machines with more than 2 axes of motion have computer/CNC control, however these days new 2-axis machines mostly have numeric control. Computer controlled filament winding machines require the use of software to generate the winding patterns and machine paths, such software can normally be provided by filament winding machine manufacturers or by using independent products.

Fiberglass direct rovings are immersed in a resin bath where they are coated with resin system. Each strand in the fiberglass roving is coated with sizing that provides secondary bonding between the fiberglass strand and the resin. Sizing can be singular resin system compatible, like polyester compatible or epoxy compatible or multi-system compatible, like polyester+epoxy+polyurethane.

Major components involved in filament winding are

1. Fibre
2. Resin
3. Tooling
4. Process equipment
5. Winding software

Fibre

Various types of fibres are used depending on application:

1. Glass fibre
2. Carbon fibre
3. Aramid fibre
4. Boron fibre
5. Basalt fibre
6. Natural fibres like jute.

Resins

Resin systems used are:

1. Polyester
2. Vinyl ester
3. Isopthalic
4. Epoxy
5. Bisphenol

Tooling

1. Tooling comprises of mandrels or moulds on which the fibres are laid, cured and subsequently extracted.
2. Moulds or tooling can be of steel or fibre glass, inflatable rubber, plastic liners, sand mandrels, wooden mandrels etc.

Process Equipment

Processing comprises of:

1. Mould or mandrel preparation.
2. Resin mixing and pouring into the resin bath.
3. Filament Winding along with program generation.
4. Curing.
5. Extraction where required.
6. Post processing where required.
7. Testing.

Winding Software

CNC Technics is tied up with CRESCENT TECHNOLOGIES, UK for using CADFIL Software on their filament winders. CADFIL Software is a sophisticated filament winding software which comes in different modules for various applications. Support for this software is supplied by both CRESCENT as well as CNC Technics and is fully compatible with SIEMENS control systems.