Advanced Technology in Mass Timber Manufacturing: New RF Press Boosts Production

Mass timber manufacturing is just as it is described—massive. In order to create these massive pieces of wood, Structural Composite Lumber (SCL) is our primary building block. It may sound like a strange product, which you may not have heard before, but SCL is essentially an engineered piece of wood that is constructed in long lengths and used to construct Mass Ply panels (MPP) and Mass Ply Lams (MPL) in lengths up to 48’.

An essential piece of the process to construct our SCL “boards” is the joint used to connect smaller pieces together to reach the lengths required for a project. Much like the finger joint used in lumber processes, the performance of the scarf joints we use is reflected in the performance of our MPP and MPL products and is therefore something to which we pay close attention.

Radio Frequency (RF) presses are used in many wood products facilities to speed up the cure time of manufactured joints connecting one piece to another. The RF behaves similarly to a microwave, generating heat in the manufactured joint and curing the resin in a much shorter time than ambient conditions would allow, all while the joint is under pressure.

Have you ever accidentally left a fork in a microwave and watched the sparks fly? Unfortunately, RF technology can be plagued by a similar issue. If proper RF High Voltage design methods are not used to mitigate an “arc” which often can burn the wood around the joint, burn holes through the wood, or lead to joint failure.

The previous RF press, which used vacuum tube technology and had been operating at our facility since production began in 2017, was plagued with a variety of issues including fatigue in the frame of the press itself, frequent arcing and burning, and longer press times than we had anticipated. We knew this equipment was of utmost importance to the facility and explored vendors to solve these issues and decided to work with USNR and Aethera to design, construct, and commission a new RF press for the plant. USNR has been a long-time equipment supplier to our industry, and we were confident in their experience to deliver the press. Coincidentally, they have also had years of experience with RF through their Mann-Russell line.

Aethera was a lesser-known supplier to us, but brought exciting new technology to the table—solid state generators. To our knowledge, Aethera is the only RF provider using solid state technology, though it has many benefits over older vacuum tube technology, such as efficiency, reliability, control and precision, compact size, improved stability and consistency, lower operating voltages, and faster response times. However, this new technology and the specific application of curing our scarf wood joints was a concern because it hadn’t been attempted before and the variability in a natural product like wood never fails to cause surprises.

It wasn’t without some struggles, but we can now say that the project was a success! USNR delivered a press that is providing consistent pressures at 180 psi with a design that is engineered to last. Aethera has delivered on their promise of providing solid-state RF generators with consistent performance over the wide variety of products the facility produces.

Of course, we always gauge our performance on production levels, and we have seen an over 35% improvement in production through the press related to shorter press times. We also anticipate production improvements by reduced upset conditions related to arcing and grounding during our press cycles, which should also improve the consistency of our joints.

Many people had a part in delivering a successful project. Our own electrical crews and millwrights did a fantastic job on the installation, helped by both USNR and Aethera staff. USNR’s controls engineers integrated their program with Aethera’s equipment, and Farnham Electric helped to integrate the press into our production line. Without a doubt our production employees were essential; their attention and involvement in the testing and commissioning and operation of the equipment provided feedback to both Aethera and USNR to ensure the project was successful. This was yet another example that when you work with Freres we bring a team that delivers for ourselves and our customers.