Structural Adhesives: A Bonding Alternative for Alternative Energy Equipment
By: Ian Quarmby , LORD Corporation
(Cary, NC — 11/04/2010)
Alternative energy applications are a key focus in today's marketplace, creating new jobs and reducing the world's dependence on fossil fuels. Solar and wind energy are garnering interest from consumers looking for cheaper, environmentally friendly power sources. To make these methods even more attractive to the end-user, energy equipment manufacturers are seeking to lower production costs while increasing product reliability. One area of potential gain is in the choice of fastening systems. Although mechanical fasteners are commonly used for securing PV and wind turbine panels, structural adhesives are becoming a popular alternative.
Structural adhesive benefits
Structural adhesive bonding is an established joining method that has been used in the automotive market for 25 years without corrosion issues. Structural adhesives offer the following benefits: reduced stress points, leaks, and corrosion; resistance to extreme environmental conditions; and, enhanced sealing. Metal-bonding adhesives are used in applications such as aluminum-skinned satellite dishes, commercial signage, and land-based military transport vehicles where thermally induced stresses and wind loads create fatigue conditions. Structural acrylic adhesives offer high shear strength (from 1,000 psi to 4,000 psi) over a wide temperature range (-40°C to 170°C), making them as strong as welding and most other conventional fastening methods. Unlike screws, bolts or rivets, which concentrate the stress at the point of attachment, adhesives spread the stress over the entire bond area. Adhesives act as a sealant by keeping out moisture, and they compensate for dimensional irregularities by filling in gaps on poorly fitting parts. Furthermore, structural adhesives offer a process-friendly solution. Minimum surface preparation is required. There is no need to pre-drill holes or fill in over screw heads, and re-work caused by burning from welding operations is eliminated.
PV panel applications
Solar panel construction offers many opportunities for structural adhesives. Adhesives can be applied between the glass and the metallic or composite frame, and are also used to attach the frame to the rack. In many systems, the bolts connecting the array to the racking and tracking systems require continual maintenance to ensure the operating integrity of the system. Reducing maintenance checks by using structural adhesives reduces costs, allowing a portion of the savings to be passed along to the consumer, which in turn makes solar panel systems a much more attractive energy option. Mechanical fasteners can also loosen over time due to wind-induced and/or structural vibration. Structural adhesives not only eliminate the problem of loosening fasteners, but also the need for maintenance followups. Structural adhesives also eliminate the weight of mechanical fasteners and improve stress distribution. And, huge inventories of bolts, washers, and screws can be replaced with one structural adhesive kit.
Wind turbine application
Structural adhesives are also finding acceptance in the manufacture of wind turbine equipment. In addition to offering reduced weight, structural acrylic adhesives have proven to reduce assembly time and corrosion protection.
A better bonding system
As environmentally friendly energy sources become more popular, manufacturers will be looking for less expensive, more viable product construction methods. Using structural adhesives in place of mechanical fasteners will enable manufacturers to build a better product faster, more simply and with less cost. There is a big push for corporations to "go green." Companies are adopting sustainability themes, and their shareholders, employees, and local communities are all interested in environmentally friendly practices. Structural adhesives offer the potential for cost savings, along with the reassurance of product durability and environmental stability.
Ian Quarmby is an innovation scientist with LORD Corporation.