Case Study

Paper Mill Manufacturing

Meeting difficult demands through out of the box thinking

There is no one standard environment. When a Swedish industrial processing expert introduced paper and pulp scanning machinery with expanded throughout, it collaborated with Sens-Tech to redevelop essential X-ray detection apparatus against a tight deadline. Remodelling equipment that is truly fit for purpose demands flexibility, foresight, and the personal touch.

Automatic detection

Sens-Tech’s long-term manufacturing partner, a Swedish industrial OEM employed Sens-Tech LINX line scan X-ray detector cameras in their XRT detection equipment it supplies to paper mills around the world. X-ray scanners are an essential component of the paper manufacturing process, enabling the automatic detection of contaminants and foreign materials amongst wood chip and pulp passing through a fast-moving conveyor system.

Owing to the harsh environment of paper mills, they housed the Sens-Tech LINX modules in a special custom-built enclosure – a design which was perfectly fit for purpose, until a new production line design presented 
a problem.

An upgraded XRT detector system was already on order by two of the world’s largest pulp producers, designed to support conveyor belts 3000mm wide – a full metre greater than the company’s existing pulp scanning module. But its redesign meant there was no longer any space for a custom enclosure to be built around the LINX module. It simply would not suit the enlarged conveyor path, meaning a bespoke detector array would be required. 

A challenge is set

Our client reasoned that no company knew the X-ray detection cameras it had been using like Sens-Tech itself, thus in December 2022 it approached Sens-Tech with a number of questions. Could the normally flat LINX line scan cameras be made curved to match the new conveyor design? Could the components of the LINX module be presented to the X-ray source at 
90 degrees to create consistent signal attenuation? Could the detector be temperature controlled and environment proofed? And, most pressingly, could Sens-Tech help design and manufacture the new detector within 
a year? 

Sens-Tech’s answer to all of these questions was an emphatic yes. Our customer had already attracted multiple orders for its new hardware, so its deadline was strict: the two companies immediately began an accelerated R&D project to jointly draft, design and subsequently implement this vital new detector array into the FlowScanner 3000. 

Clarifying project scope

Figure: Flat linear detector/ boards at 90Deg and U shaped detector set up

Sens-Tech welcomed the opportunity to meet its customer’s unique needs and, in the process, spearhead new advancements in X-ray detection technology. Working together to refine the preliminary sketches into a workable design, the two companies finalised a specification document in April 2023, leaving just 16 weeks for final product design and 16 weeks for production and delivery. 

It was decided that the companies would split certain design and manufacturing requirements between them. Our client would deal with the complexities of integration in its Swedish manufacturing plant, including ensuring the implementation of radiological design, shielding, and the provision of air and water for cooling. Sens-Tech would produce the detection hardware itself, manufacturing two units from its UK base. This hardware would be designed around a modular detection system comprising 38 precisely aligned dual-energy detector heads based on XDAS technology, along with three GIGE interface boards, and other gauging detection hardware to ensure the unit’s adherence to operating parameters.

Along with the above questions, the mechanical requirement was sketched out by their designers and was shared with Sens-Tech as a starting point. The sketch was not exact but helped to trigger discussion as well as out of the box thinking.

The following initial drawings and specifications of previously designed and installed ‘curved’ detectors were sent through and a technical mechanical design meeting was scheduled in the diary for January.

Our client had been purchasing LINX detectors from Sens-Tech for several years but due to the harsh paper mill environment they had to produce enclosures for the LINX detectors. However, for this project it would not be practical for additional enclosure. Due to the size and form factor of the proposed detector the special design would have to be self-contained and robust and to not require secondary housing.

Figure: Flat linear detector/ boards at 90Deg and U shaped detector set up

The power of the pivot

R&D can be a difficult process to navigate – and sometimes the best option is to change course. Although a preliminary design had been settled on, the realities of the post-specification design phase revealed to Sens-Tech’s engineers that a change was required. To properly serve their needs, the final product would need to go beyond the project’s original plan.

The company’s initial agreement with our client centred around a design which employed one horizonal base detector and two parallelogram vertical detectors, mechanically connected to cover the edges of the curved conveyor. To fully meet the demands of the environment, it became clear that the detector would be better housed in a single enclosed unit, curved to match the dimensions of the conveyor housing. 

Sens-Tech’s engineers were fully committed to the project, and the team was offered the executive oversight which enabled it to react to the need for a scope change. Sens-Tech opted to use its agility to pivot and create a product which indeed went beyond the original spec. Not only did the redesigned detector better meet the needs of our client and its customers, it added additional benefits to the product: this integrated unit would be easier to install or replace, easier to align, and aid in routing water cooling channels and airflow for heat sinks and electrical Peltier coolers.

Project scope

The scope of the project was to design and build a special large detector to ‘wrap round’ a curved/shallow u-shaped conveyor.

Two detectors were required, the first one was to inspect a ~2.4m tunnel of wood chip and the second detector was to inspect a ~3.0m tunnel of wood chip. The large active detection width with large X-ray signal attenuation at edge detectors meant that each 1.6mm dual energy Gadox/CsI 102.4mm detector headboard need to be presented perpendicular to the source at 90 degrees. The previous solution was to install a flat detector across the base of conveyor so the distance between the source and the detector increases as the beam moves out to the edges of the conveyor.

In addition to the above requirements the detector also needed to be IP rated up to IP67 standard and be temperature controlled.

Figure: Original Design

After a final pre-project/project kick off meeting the following initial specification was agreed for two identical detectors for the narrow and the wide belts – to keep things simple:
  • XDAS detector electronics with 1.6mm pitch dual energy (DE) detector boards
  • Low energy 0.3mm Gadox scintillators and high energy 4.0mm CSI
  • System to consist of one horizontal base detector and two parallelogram vertical detectors
  • Thirty perpendicular 90° 1.6mm DE detector headboards on the horizontal section
  • Eight perpendicular 90° 1.6mm DE detector headboards in total on the two vertical sections
  • Four SP boards in total; one for each vertical and two for the horizontal section
  • Vertical sections to be adjustable ~150mm each way to allow for belt to move
  • Three GIGE interface boards and power/trigger connectors for each of the detector sections
  • Cooling via heat exchangers to cover the side profile surface areas to be provided by client
  • Blanked off compressed air in and out connections on each of the three detector sections
  • Internal fans for air circulation
  • IP54 rated – limited ingress/splashproof acceptable for application
  • Client took care of radiological design i.e. lead/steel lining
  • Mechanical fixtures to connect all 3 pieces to be shipped with each of the three sections
  • Allowance for transport brackets has also been included
  • Mounting points required on side walls for insulation and heat transfer plates
  • X-ray shielding to be designed for 120keV X-ray source to protect electronics

Figure: Original Design

A specification document was confirmed in April 2023 and 16 weeks design / 16 weeks build time was allocated with a December shipment confirmed

Thermal stability
In addition to the above mechanical design requirements, as mentioned above, precise and reliable thermal control was required. Sens-Tech’s solution featured channels of hot and cold water underneath the electronics within the detector itself and a heat exchanger with an integrated fan for air circulation.

Clean execution on time

The biggest hurdle for any R&D project is the potential to become mired in development iterations. To ensure success, both companies maintained clear and regular communication and kept robust, detailed specification documentation throughout the process, adhering to a strict commitment to completing the project on time.

Agility proved the key to meeting that deadline. Sens-Tech engineers were offered the space to think, the breathing room to create, and had the hardware ready to get the job done. Basing the project around its tried-and-tested XDAS platform meant working with detection technology which has proven its worth time and time again in critical infrastructure. XDAS was also a familiar technology: it powers the X-ray detecting capabilities of the LINX modules previously used. Crucially, it was ready to deploy—Sens-Tech always keeps stock on hand to ensure it can react to manufacturing challenges without long lead times.

The first of two scanner modules was shipped to our client in December 2023, just a year after talks began; the second, manufactured while the first was being installed and tested, was shipped shortly after.

To discuss your project, contact:
Paul Hurtado, Head of Sales and Marketing at Sens-Tech.

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