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The new Crestabond primer-less MMA structural adhesive from Scott Bader has been successfully trialed by Interboat NL in The Netherlands as a much faster and cleaner way to fit the GRP engine foundation part in their 5.7 m long fibreglass sloop compared with traditional glass and resin over laminating. A significant reduction in the overall assembly time of over 60% was achieved. Shop floor conditions for their operators were also improved when using this new adhesive assembly process, as there was far less styrene exposure and no dust from grinding the hull surface, as normally done prior to over laminating; the only surface preparation required with Crestabond was to wipe clean all the contact surfaces to be bonded with a solvent to remove any contaminants such as grease and dirt.
Interboat annually produces around 220 high quality fibreglass cruisers, tenders and sloops in a range of sizes from 5.7 to 10.5 m. The head office and main showroom is in Loosdrecht around 20 km south east of Amsterdam, with their production operations located in Zwartsluis, around 15km from Giethoorn. They have four dealers covering the Netherlands, plus a network of other dealers throughout Europe, as well as one in the USA. As a forward thinking company with a modern approach to manufacturing, Interboat is always looking for improvements in production. Scott Bader was introduced to Interboat by their composites distribution partner Advanced Plastics NL, who distribute the full range of Crystic® resins, gelcoat and adhesives in The Netherlands.
The bonding trial on the 5.7 m sloop was set up and run earlier this year by Scott Bader’s adhesives sales development manager Patrick O’Shea at the request of Interboat’s production manager, Wim Kooman, who was initially skeptical of the claims made by Scott Bader about their new Crestabond structural adhesive; he wanted to see a practical bonding trial demonstration first hand on one of their smaller joining applications to prove that it can significantly reduce production times and provide a better bond strength performance than over laminating.
The Bonding Trial – Step by Step
Step 1 was the GRP surface preparation, which was a simple solvent wipe with a clean cloth of the bond areas on the engine foundation base and the hull.
Step 2 was to position the engine foundation part ‘dry’ (i.e. with no adhesive applied yet) in its correct place in the hull and to draw an outline of the exact position with a marker pen; the GRP engine foundation section measured approx 2.2 m long by 1 m wide.
Step 3 was to then lift clear the engine foundation section and to then apply Crestabond M1-20 adhesive to the hull surface using an air assisted 380ml cartridge gun, following the pre marked bond line, which was approximately 6 meters all round. Crestabond M1-20 was selected from the range for this particular application as being the most suitable with its 16 - 22mins working time and its gap fill properties up to 25mm.
Step 4 was to then swing the GRP engine foundation section back over the hull and carefully lower it down onto the adhesive and position it exactly in place using the marked outline. Due to some dimensional variance at certain contact points, it was necessary to apply a bit more adhesive to fill any gaps. A small brush was then used all around the bond line to smooth out any surplus adhesive. Wooden struts were also bonded into place at this point.
The entire assembly process from start to finish took only 15 minutes using Crestabond M1-20, with minimal mess, waste or clearing up needed; a significant time saving compared to the 40 minutes typically taken to surface grind and over laminate the same part, plus all the associated mess and styrene fumes.
The sloop was then left to allow the bonded section to cure. Crestabond M1-20 fully cured in 70 minutes and was then ready to undergo a bond strength test of the engine foundation jointing to the hull.
Bond Strength Testing
The bond strength test was carried out with the sloop filled with 180kg of ballast, making its total weight 500kg. The lifting gear was attached to the fixtures which had been secured to the top of engine foundation section and then the craft was lifted up clear of its cradle and left to hang so that the only the adhesive bond line was taking all the strain. The bond maintained its integrity and after a thorough inspection of the joint line by the Interboat team, they confirmed that the Crestabond joint was intact all around the engine foundation section.
After the trial Wim Kooman stated: “I am impressed with both the rapid bond performance and workability of this new Crestabond adhesive. For such a strong bond to be achieved in just over an hour with no preparation other than a clean with solvent really surprised me. When we lifted the sloop up off the cradle with the crane I was really not expecting the bond to hold, but it did. Having seen it I am now convinced. It has really opened my eyes to much bigger bonding opportunities on some of the larger cruisers we make, where I think we can make huge savings in production time, such as in deck to hull bonding. This will be our next bonding trial with Crestabond.” He went on to say "What I also liked was the positive reaction of all the shop floor workers. They took to applying the Crestabond product with the air assisted gun easily and were very happy not to be wearing full masks or having to use the grinding machine to prepare the hull surface. Bonding is definitely a good way to help create a cleaner and better working environment on the shop floor.”
The range of Crestabond adhesives is a new addition to the Scott Bader portfolio, strengthening over 25 years of proven experience in structural adhesives technology in composite applications with its well established range of Crystic Crestomer® adhesives.
There are five Crestabond adhesives in the current range designed to bond a wide variety of composite, metal and plastic substrates. All have a 10:1 mix ratio, offering a choice of working times from 4 minutes up to 100 minutes to suit most production processes.
Crestabond is available from stock in a range of pack sizes depending on usage requirements either in 380ml coaxial cartridges, or for bulk dispensing applications in nominal 20 litre pails or 200 litre drums. For more information on the Scott Bader adhesives range visit www.scottbader.com/adhesives . For further details about the range of craft available from Interboat NL, log onto www.interboat.com .
About Scott Bader
Scott Bader was established in 1921. Today it is a £180 million multinational chemical company, employing 560 people worldwide. It is a common trusteeship company, having no external shareholders, with a strong commitment to support its customers, workforce and the environment.
Scott Bader’s headquarters is based in the UK where they have purpose-built, state-of-the-art technical facilities that provide R & D as well as complete evaluation, testing and application support. They have manufacturing facilities in the UK, France, Croatia, The Middle East and South Africa. For further information regarding Scott Bader, please call +44 (0)1933 663100, visit www.scottbader.com or e-mail info@scottbader.com. |
