Manufacturing Solutions for Medical Technology
Manufacturing Cryogenic Pressure Vessel Heads for MRI Scanners
Standex Engineering Technologies Group and its Spincraft UK business, a leading metal forming solutions provider in Newcastle in the North East of the United Kingdom, has manufactured thousands of cryogenic pressure vessel heads for MRI scanners used in the medical imaging industry. Spincraft is the leading supplier of these components that are critical to the function of MRI scanners like the Siemens Magnetom, an industry leader in accuracy and resolution with over 30 thousand units shipped over the last three decades.
The Origins of our Involvement
Spincraft has been involved with the system manufacturer since the early days of widespread MRI use in clinical environments. We have collaborated closely with our customer’s design team to understand their technical needs and concerns. Decades of building a relationship and prioritizing customer intimacy allowed Spincraft to design our forming solutions with the flexibility to respond to and accommodate substantial design changes as scanner technology has advanced while keeping costs within the customer’s budget.
Over the years, Spincraft has developed new forming methods and processes to meet the increasingly demanding tolerance requirements that MRI scanner pressure vessels require. The design of these structures has changed to be lighter and more cost-efficient, with more power and better imaging that drives thinner but stiffer vessel construction. As these designs have evolved, the need for component repeatability and maintaining cost efficiency has not wavered.
Lifting the Lid on the MRI Scanner’s Internal Construction
Most people only see the outside plastic covers on an MRI scanner. Underneath this is the main pressure vessel assembly known as the Cryostat. The Cryostat has three layers with formed metal components made by Spincraft.
The outer layer is known as the Outer Vacuum Chamber (OVC). This stainless steel OVC keeps the contents of the Cryostat under a vacuum to help with conductive insulation, much like a thermos flask keeping heat out of the contents rather than keeping heat in.
The next layer is a Thermal Shield made from aluminium. It has a highly reflective surface that helps provide a barrier to heat transmission by radiation.
Inside the Shield is the Helium Vessel (HeV) that contains the liquid Helium and a selection of electromagnets.
Why is this needed?
At the core of the MRI scanner are a number of extremely powerful electromagnets that have many thousands of times the power of the Earth’s magnetic field. These magnets align protons to create the images needed for clinical examination. These magnets are cooled by the liquid helium until they superconduct — requiring significantly less electrical power.
The Cryostat must maintain these cryogenic temperatures and vacuum pressures to keep the magnets superconducting. Vessel heads made by Spincraft are an essential part of cryostat performance. When the vacuum is applied, the Spincraft heads are subjected to an atmospheric force of about 35 tonnes (77,000 lbs) and maintain the critical alignment between the outer vessel shells and inner bore tubes without fail.
Our customer has continually relied on Spincraft to deliver thousands of parts that consistently meet the most stringent quality requirements needed for accurate medical diagnosis and advanced neurological research.
The Manufacturing Process
The experienced Spincraft team has undertaken years of methodical improvement to streamline and optimize the manufacturing process. Our current process looks like this:
1. An operator moves the material to the plasma profiling machine where a unique serial number is assigned for part traceability in the entire manufacturing sequence.
2. A square plate is cut into a circle for the spin forming process. The surfaces and edges are cleaned for safety and quality.
3. The inside diameter of the part has a weld prep machined in place.
4. The parts are spun formed using a multi-stage CNC process with multiple tools to ensure all requirements are met.
5. After forming, the part is fully inspected and validated against the customer’s requirements.
6. Once confirmed correct, the part is prepared and packed for shipment.
The Spincraft team has a proven track record as an innovative solutions provider in the medical technology sector, as well as other industries including Aerospace and Defence. We encourage you to contact a Spincraft representative to discuss how we can collaborate and support your most advanced metal forming needs.