FASTENINGS
IMPROVED ASSEMBLY FOR POP-TOPS
At this point, process efficiency and consistency began to drive the choice. When they compared surface bonding
P
op-top roofs for campervans are a fast-growing market. These roofs are typically GRP laminate
structures, often with gel-coat finishes on both sides to achieve the smooth appearance expected by the end user. As production volumes rise, designers are looking for fastening solutions that maintain visual quality while supporting fast, repeatable assembly.
Design and manufacturing challenge A pop-top roof requires multiple attachment points, often used to secure interior components such as handles or curtain rails. The design requirements are clear: No visible fasteners on the exterior moulding, and no through-bolting that breaks the clean outer surface. Many manufacturers use surface-bonded
fasteners. In more flexible production environments, such as hand lay-up or vacuum infusion, this approach works well.
Surface bonding offers strong attachment and design flexibility without complicating the laminate design or forming. One of bigHead’s customers was
producing 60 pop-top roofs per week, with 26 fastening locations per roof. At that scale, adhesive bonding introduced positioning variability and additional clean-up steps that became increasingly difficult to manage within the available time window. As production increased and fastener
installation became a repeated manufacturing operation, the cumulative impact of bonding each fastener cleanly, accurately and consistently began to affect their throughput. Each fastener required: Precise
spacing; Controlled adhesive application; Cure time, and careful handling to avoid rotation or misalignment.
Why embedding became more appropriate for this production context Rather than treating fastening as an isolated task, the team evaluated it within the context of their evolving manufacturing workflow. They needed a blind fastening method, but they also needed to increase throughput without compromising the exterior surface. As they transitioned towards rigid
tooling and RTM processing, the process itself now supported embedding.
38 / WELDING WORLD MAGAZINE - ISSUE 04 - AUGUST 2026
with embedding, the advantages for their production context became clear. Embedding would remove the repeated adhesive-bonding operation and also reduce handling steps. This would improve consistency of fastener positioning as well as support the cycle times required for higher-volume production. Embedding also eliminated bond lines and the risk of adhesive overspill. And crucially, it removed the need to individually bond 26 fasteners per roof. For this customer, embedding a
standard bigHead fastener provided a clean, repeatable solution. The company moulds the inside and outside surfaces simultaneously using a solid tool, with the bigHeads embedded directly into the laminate. The tooling controls spacing and alignment, ensuring consistent results. The outcome: a cleaner, faster
manufacturing process and for this customer, embedding delivered clear benefits. These include eliminating visible fixings on the exterior GRP surface and removing several individual bonding operations per roof, as well as reduced rework by minimising rotation, misalignment and adhesive-related variability. All of this supports higher production volumes and enables cleaner, more efficient assembly workflows. Surface bonding remains an effective
option for many manufacturers, particularly those using hand lay-up or vacuum infusion. But in this case, the shift to RTM meant that embedding became the more efficient and sustainable choice for the customer’s production context.
www.bighead.co.uk
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