The University of Southampton is a world leader in photonics and optoelectronics.
When it commenced plans to install a new JEOL JBX-A9 Electron Beam Lithography System in its state-of-the-art cleanroom (the Southampton Nanofabrication Centre), it knew it needed support from an expert third-party supplier to build the right structural machine base.
Having reliably and expertly provided structural machine bases for various types of cleanroom equipment (including a deep ultraviolet (DUV) scanner) at the University, our long-standing relationship with them made us the immediate choice.
We were contracted to design and install the structural machine base and perform specialist strengthening of the cleanroom floor - as well as the floors throughout the facility’s tool move-in route - to support the tool’s significant weight and size.
Due to our strong relationship with JEOL, the tool’s OEM, we were also contracted to handle the equipment move-in to the facility on their behalf.
This project would see us survey, design, manufacture and install our largest-ever rigid structural machine base - and for a tool that was significantly heavy, large and intricate. As such, we knew we’d encounter a fair few challenges along the way.
But we were ready for them. With the ingenuity of our highly experienced engineers on our side.
Here’s how it went.
What We Needed to Consider
Firstly, a JEOL JBX-9500FS Electron Beam Lithography System is not a small or dainty tool. It’s a significantly large and heavy piece of equipment, weighing around four tonnes in weight.
The tool’s weight meant it would exceed the loading capacity of the client’s cleanroom floor. And as such, it would need to sit on a suitably strengthened load-bearing structure prior to installation.
Secondly, the lithography tool is extremely sensitive to vibration. As a result, it would need to conform very rigidly to the OEM’s set vibration specification and remain isolated from the existing raised access floor to perform accurately and as required.
Therefore, the design required a rigid structural machine base that provided load bearing and a high level of structural stability - and that would not induce any additional vibrations.
Thirdly, and lastly, the University’s raised-access floor (RAF) is around twice the height of the average cleanroom, sitting at 1.2 m.
Because our structural machine base would need to match the height of the RAF, this posed a challenge. Taller bases are inherently less rigid than shorter ones. So, we’d need to ensure the structure could match the height of the RAF while being rigid enough to meet the equipment’s vibration specifications.
Here’s what we did.
Designing and Manufacturing the Structural Machine Base
We started by visiting the cleanroom and performing a 360-degree dimensional light detection and ranging (LiDAR) survey of the predetermined tool location.
This involved capturing precise measurements of the cleanroom environment and capturing obstacles under the RAF where the base would be positioned (for example, under-floor services). This would allow us to create a 3D design of the structural machine base that would fit within the cleanroom’s spatial constraints.
We then took vibration measurements of the concrete slab under the floor and around the footprint where the tool was going to be installed. This would help ensure that the slab’s “natural state” vibration was below the tool’s maximum vibration specifications. Electromagnetic field and acoustic sound pressure levels were also monitored to meet the tool’s other climatic requirements.
With all data collected, our mechanical design team produced a first-draft mechanical design, drawing on a wealth of experience and design knowledge from previous successful machine-base installations.
We supplied a 3D mechanical design to our vibration specialists to perform finite element modelling (FEM). This involved extrapolating the data and inputting it into computer modelling software, including the tool’s individual foot loads and its centre of gravity. The purpose of this was to simulate the current slab’s vibrations and the operational stresses on the machine base to predict whether the base was likely to perform below the tool’s maximum vibration specification.
Due to the unusual height of the RAF and weight requirements of the tool, we trialled several iterations of the structural base design. Before we were finally satisfied that it would meet those requirements with the third design revision.
We then manufactured the base. The end result was a two-tonne, steel-framed and powder-coated base that measured 1,825 x 1,900 x 1,180 mm in total.
Since 2014, all load-bearing structural steelwork products are legally required to be manufactured and CE marked to BSEN1090. Our fabricator is also approved to Execution Class 2.
Installing the Base and Equipment
Once the structural machine base had been manufactured and was ready for use, we sent a team of three engineers to the client’s site to install it.
We did this by lowering the base into a void created through the tiles floor, and aligning, levelling and fixing to the concrete slab using a dammed cementous bonding grout.
Sensitive equipment like this is prone to vibrational damage during a transport move, cementing our decision to choose air skates as our transport method. Similar to a hovercraft, this provides a soft cushion of air as a flotation device to move the equipment to its destination.
However, we needed to create the right environment to use air skates. This transportation method requires a sealed floor to limit air loss during the move. We created a flat-plated floor topped with over 100 (3x1000x2000 mm) stainless steel sheets, joined with temporary taped seals.
With the floor in place, we installed an air compressor with a dry high volume air capacity of six and eight bars of air pressure - a figure which varies depending on the load of the tool in question. We ran the airline 120 metres long from the compressor to the final tool destination and tested this line, ramping it up to full system pressure up to the air skate flow control manifold. The team blew out each skate output line, removing any residual moisture and debris before the move.
The Southampton site presented us with a variety of unique challenges. Once unpacked and lifted clear of its crate base using a forklift truck (FLT), the tool was lifted on forks sat on dampening rubber and moved a short distance into the building’s loading area, ready for air skate setup.
While our original plan was to lift and skate from beneath the main feet of the tool, the size of the air skates and the pinch point dimensions of the move route meant that this was not possible. We needed an inbound lifting location for the tool, and agreed on a suitable frame cross members with the OEM.
This new skate position meant we had to offset different lifting point heights using variable thickness packers across the surface of the air skates. Once set, the tool was ready to be lifted.
The team increased and adjusted the air pressure to all four skate pads until it was level and balanced. This was a challenge in itself, as the offset centre of gravity of the tool meant that each pad required a different pressure.
With the tool now ‘floating’ we carried out a push test. However, the initial floor friction required the pressure to be increased further to gain suitable free movement.
We gently floated the tool along the move-in route, with the trailing air hose fed behind it as the move progressed. However, we encountered further challenges along the way. The goods load lift we planned to use was rated to handle the load of the tool but failed to lift to its normal full height, falling short by around 10mm. We needed to create a ramp using staggered, tape-sealed stainless steel sheets - and even this 10mm ramp elevation required an increase in air pressure (and bodies) to get the tool through.
Once we reached the flat-plated floor, the tool moved with ease. It required a team of four to guide it through very narrow corridors and through doorways to its final position within the cleanroom. Here, we gently aligned it, which involved lowering the tool, taking measurements, raising it and making adjustments until we were satisfied with its final position.
All that was left to do was to clear the air system and floor plates from the site, and the project was complete.
The Technical Equipment Manager at Southampton University, was delighted with the results:
“The IES team overcame significant site-specific challenges to complete this design and install. From planning and structural machine base design through to manoeuvring the tool to its final location, we were impressed with the communication, technical skills and problem-solving abilities of the entire project team.”
A Structural Machine Base Design & Manufacture Service You Can Rely On
We’ve been designing, manufacturing and installing bespoke rigid structural machine bases for end-users in high-technology industries since 1991.
Our turnkey service covers everything, from the design and manufacture of your structural machine base to installation and post-installation vibration checks.
Learn more via our Structural Machine Bases service page here.
