Tips & Tricks for Manufacturing GRP Components

Processing Tips for Mould Making:

The steps in the Laminating Process

1. Gelcoat Application
The gelcoat can be applied by brushing or spraying. A coating thickness gauge is used to ensure that the layer has been evenly applied (recommended thickness: 1000 µm). When using a conductive tooling gelcoat, the earth connection point must be created after the gelcoat has cured.

2. First Laminate Layer
After the gelcoat has cured, the process of applying the laminate can begin. The first layer of laminate after the gelcoat in particular should be applied with great care. During this process, it is especially important that all air bubbles between the gelcoat and this first layer are eliminated by rolling. Fibreglass mats with an area density of 150 g/m² or 225 g/m² and with a fibre weight of 15 tex should be used for the first layer.

3. Lamination
After the first layer of laminate has been left to cure overnight, it can be sanded down using sandpaper. Any dust created should be removed. Depending on the mould’s purpose and the required wall thickness, more laminate layers can be added to the structure until the mould meets the specifications. BÜFA®-Tooling Resin is suitable for building up 2-12 layers of CSM in one step, thanks to its low profile technology.

4. Post Curing
The laminated mould should be post-cured on the master for 8 hours at a temperature of approx. 70-80°C. We then recommend reinforcing the mould. The properties of the master play a crucial role in determining the quality of the mould and its surface. The degree of gloss of the master and any unevenness will be transferred to the mould. Special attention must therefore be given to the surface of the master. Ensure that the environment is dust-free when making moulds. We recommend using our BF 700 carnauba wax (BÜFA®-BF 700 Mould Release Wax Paste) for releasing moulds from their master. Products from the BÜFA®-Conductive Tooling System are ideal for processing using machinery. We recommend using the sophisticated, robust and easy-to-operate equipment made by BÜFA Tec. Examples:

Dispensing Machines
BÜFA®-Tec Polybar

Gelcoat Spraying Units
BÜFA®-Gelcoat System
BÜFA®-Tec GSU ES1
BÜFA®-Tec GSU ES1 “Easy Lift”
BÜFA®-Tec Delta EVO-LINE
BÜFA®-Tec Sigma 6 EVO-LINE

Lamination Roller Systems
BÜFA®-UNI 150 EVO-LINE
BÜFA®-UNI 275 EVO-LINE

Fibre Spraying Systems
BÜFA®-Tec Delta EVO-LINE
BÜFA®-Tec Sigma 6 EVO-LINE

Tips & Tricks for Mould Making

For making the Highest Quality GRP Moulds

Only materials with the best product properties should be used to make the highest quality GRP moulds.

1. Material Required
    •    BÜFA®-VE-Tooling Gelcoat in spray or hand quality
    •    BÜFA®-Tooling Resin 
    •    Curing agent 
    •    Glass fibre mats - grammage as required
    •    BÜFA®-Resin VE 0910 (1st layer of resin)
    •    Glass non-woven material
    •    Release agent or release paste 
    •    Release lacquer - transparent or green 
    •    BÜFA®-Bonding Pastes 
    •    Sanding and polishing agents, e.g. from the BÜFA®-BF-Series

2. Helpful Tools
    •    Brush, BÜFA®-Tec Polycon Spray Gun 
    •    or a BÜFA®-Tec Gelcoat Spraying System, such as an ES1
    •    Laminating and de-airing rollers

3. Procedure
After application of release agent to the master, the mould tooling gelcoat is applied. If the spray version is used, please apply in 3 layers with a thickness of 200?m each. Wait 3-5 minutes between the individual layers. This is necessary to give the air sufficient opportunity to escape. After curing (squeak test), a layer of laminate with a 150g/m² mat together with the BÜFA®-Resin (e.g. BÜFA®-Resin VE 0910) is applied. For difficult corners and corrugations, you can apply a BÜFA®-Bonding Paste (liquid mat) with a brush to even them out. This prevents air gaps during lamination. 

Monitoring is easy: during curing, the colour changes from beige to white. If this does not happen, the layer thickness is not sufficient. Post-curing is recommended after initial curing. For this the mould is cured again with the master at 70°C for 8 hours. After cooling, the new mould can be demoulded. In order to fit a metal frame, blocks of balsawood or foam should first be stuck to the points of contact. BÜFA®-Sandwich Adhesive is best for this. This approach stops the metal frame from showing through because of different heat expansion. The mould can now be given the degree of gloss required and then release agent can be applied. For the first demoulding, an additional application of BÜFA®-Separating Lacquer is recommended.

Notes
In order to create a surface that is as high quality as possible, we recommend using it together with a BÜFA®-Resin (e.g. BÜFA®-Resin VE 0910). After application, this layer should be allowed to cure for about 8 hours. Then continue as above. The first-layer laminate mentioned above prevents premature detachment of the gelcoat layer from the subsurface with complicated and/or large moulds.

Repairing a GRP Mould

How do you Repair Imperfections and Cracks in a GRP Mould?

Material required
Release agent, BÜFA®-Bonding Paste, BÜFA®-Tooling Gelcoat, BÜFA®-Skin-forming Agent, BÜFA®-Tooling Resin, peroxide, grinding and polishing pastes from the BÜFA®-BF Series

Helpful tools
Cotton cloth, small cup, spatula, wooden wedges

Procedure
Always handle your mould with care! Use a high-quality release agent. Work with the recommended amount of peroxide and at an appropriate temperature (at least 16°C). Use only wooden or plastic wedges for demoulding. Depending on the release agent system you use, it may be necessary to freshen up the mould after a few demoulding processes.

• Wax-based systems: after 3 - 8 demoulding processes
• Semi-permanent release agent: after approx. 10 - 50 demoulding processes

Always use a clean cotton cloth to avoid traces of polish. Accumulations of styrene should be removed with a mould cleaner. Then put the mould into an oven for 8 hours at 40–60°C to accelerate the evaporation of residual styrene. After cooling, apply the release agent exactly as you would to a new mould.
 
How to carry out a Repair:
Minor damage can be repaired with BÜFA®-Bonding Paste (for higher temperature resistance, choose a BÜFA®-Bonding Paste) and a BÜFA®-Tooling Gelcoat. Apply BÜFA®-Bonding Paste with curing agent to the mould and allow it to cure. This is followed by a coat of BÜFA®-Tooling Gelcoat (+ 4% skin-forming agent and 2% curing agent). Then sand/polish the repair and apply releasing agent. With more serious damage, you should proceed in a similar way, but part of the laminate must also be replaced with a mould tooling resin. Sand the damaged areas until no more signs of damage are visible and build the laminate up. Then continue as above.

If you have any questions, please feel free to send us an email or give us a call.

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