Bonding of fasteners with ultra-fast light curing adhesives

Paul Boughton

Developments in fastener technology coupled with new light curing adhesives that cure in less than five seconds have combined to create new design and assembly options for plastics components while enhancing quality and reducing manufacturing costs.

International fastening and assembly specialist Bollhoff and manufacturer of industrial adhesives DELO have joined forces to introduce ONSERT - an fastening system that enables the bonding of fasteners in seconds to a wide range of substrates. ONSERT can be used on most thermoplastics, CRFP (carbon fibre reinforced plastic), SMC (sheet moulding compounds) GMT (glass mat thermoplastics), glass, lacquered or electroplated surfaces, metals, stainless steel and aluminium. As no heat is involved in the light curing process there is no risk of discolouration or deterioration of mechanical properties in the substrate.

The technology is expected to deliver significant benefits to manufacturers in the automotive and electronic industries where it will replace moulded inserts as well as traditional mechanical and heat based fastening methods.

While the bonding of fasteners is an established technique in the aerospace industry, where it provides excellent mechanical properties, conventional processes can involve time consuming mechanical operations and curing times of up to 24 hours.

ONSERT enables high performance fasteners to be placed virtually anywhere, automatically, on a plastics part without the need to design-in large bosses to accommodate moulded-in inserts. Unsightly sink marks are therefore eliminated on mouldings, improving product appearance, while heat, pressure and cycle times can be reduced to improve process efficiency. By allowing engineering designers to locate fasteners in the most favourable position, functionality and assembly operations also can be optimised.

The new fastening system is based on several technological advancements - Bollhoff over-moulded metal fasteners, patented LED light source design and placement technology plus the latest DELO adhesives that light cure fully in seconds rather than hours.

Aging and adhesion tests recognised in the automotive and aerospace industries have so far shown that the joint strength of bonds created with ONSERT do not deteriorate over time.

ONSERT has already been adopted by a leading European automotive manufacturer for the assembly of plastic over-moulded threaded fasteners onto composite body panels. Further applications are expected to develop in industries where components need to be joined to a wide range of substrates.

For more information, visit www.bollhoff.com/uk

Fig. 1. ONSERT enables high performance fasteners to be placed virtually anywhere, automatically, on a plastics part without the need to design-in large bosses to accommodate moulded-in inserts.

Fig. 2. Fastening technology from Bollhoff and ultra-fast light curing adhesives from DELO have combined to create ONSERT which offers fresh design and assembly options for plastics components.

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