Engineered Wood Applications

Finger Jointing

Finger joints make it possible to manufacture glulam boards and solid timber products of any desired length from short boards or solid timber pieces. By finger jointing wood together a high-strength longitudinal bond is created between shorts to yield a high-quality semi-finished timber product that can either be used directly in construction or further processed into engineered wood products such as glued laminated timber, etc.

LOCTITE^® wood adhesive products are the ideal solution for manufacturing high strength and durable finger joints. Customers have a wide choice of application methods that meet the specific conditions and requirements of their operation, including finger jointing plywood. LOCTITE^® adhesives are high performance systems that react rapidly and lend themselves to fully automatic, continuous production under a broad range of manufacturing concepts.

Applications of finger-jointed timber include:

• Boards for the production of CLT, glulam laminated beams, as well as glued solid timber (duo and trio beams)
• SST (finger-jointed solid sawn timber)
• Flanges in I-joists and formwork joists
• Finger-jointed components for wood construction (e.g. posts, studs, rafters, and joists)

For manufacturing finger joints, two fundamentally different application methods can be used:

• Comb application
• Contactless application KEBA (Keilzinken Berührungsloser Auftrag)

KEBA was developed in co-operation with application system manufacturers with the aim of offering the user greater precision, cleanliness, flexibility, and process reliability in production environments.

Today, KEBA is used in a variety of versions (depending on the manufacturing process), some of which include integrated continuous application monitoring. Application monitoring is based either on an opto-electronic system (camera solution) or on the PSS (Purbond-Safety-System). The PSS currently represents the state of the art in adhesive process monitoring.

The new PSS provides the greatest possible process reliability in finger joint production at the lowest possible expenditure.

Face Gluing

Face gluing is used to either make a thicker or taller piece of wood depending on how you join the wood together. Gluing wood face to face is an easy way to make custom wood thicknesses or panels for a variety of woodworking applications.

Surface gluing refers to the joining of wood pieces and boards either on the broadside or the edge to manufacture multi-layer laminated timber products. 

Edge gluing is used among other applications in the manufacture of single-ply panels that are subsequently processed into cross-laminated timber products.

LOCTITE^® adhesives are applied in a suitable application process. After application of the adhesive, the adhesive-coated parts are pressed for a defined period of time in a cold process - no additional energy (heat) is required.

The following products can be manufactured with the face gluing application process:

Broadside:

• Glued laminated timber
• Duo and trio beams
• Special structural elements
• Cross-laminated timber

Edge:

• Layers for cross-laminated timber
• Box beams
• Edge beams

I-Beam

I-Joists and I-Beams are used as formwork in concrete construction and as rafters or posts in wood construction to provide structural support. Due to the particular process conditions, adhesives in the production of I-joists and engineered wood I-beams must meet stringent requirements. The production of an I-joist and I-beam construction basically involves three gluing steps:

• Bottom and top flange finger joints
• Web-to-web joint
• Flange-to-web joint

In the specific production process, adhesive application at each individual gluing station (finger joints, web-to-web, flange-to-web) is accomplished either via a needle-valve or a comb system. The use of LOCTITE^® wood adhesive products makes it possible not only to reduce cycle times but also to achieve very high strengths.

Many years of development and experience have consistently demonstrated the excellent performance of LOCTITE^® wood construction adhesives in this field of application.

Increasing Adoption of Engineered Wood for Large Structures

With the increased demand for sustainable design, building materials have evolved to reduce the direct and indirect impact on the environment. During the construction lifecycle, buildings use energy, water, and raw materials; generate waste and give-off emissions. Cross-laminated timber is gaining in popularity because it is easy to install and generates almost no waste on site. It offers high strength and structural simplicity necessary for cost-effective buildings, as well as a lighter environmental footprint than concrete or steel.

Constructed of several layers of kiln-dried lumber, CLT is stacked in alternating directions, bonded with structural adhesives and compressed to create a panel. The adhesive used in CLT applications needs to meet stringent product standards and must be certified to ANSI standard. These adhesives are designed to balance the ratio between open time and pressing time and provide maximum flexibility for the manufacturer.

There are three manufacturing methods for CLT – Cold Press with Formaldehyde Adhesive, Radio Frequency (RF) press and Cold Press with Formaldehyde Free Adhesive. Each method can support three- to seven-layer panels. The primary differences between each method involve:

• Manufacturing set up and resources
• Adhesive type
• Energy use

As CLT manufacturers continues to transition to more efficient manufacturing processes, adhesive is critical to adopting more efficient and sustainable processing. Henkel’s LOCTITE^® HB X Purbond is a one-component polyurethane adhesive. It is free of solvents and formaldehyde and meets the most rigorous strength and emissions guidelines for CLT. Henkel’s LOCTITE^® HB X Purbond is designed to work with Cold Press manufacturing without the need for respirators and the moisture curing process does not require heat and reduces energy use.