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Product & Design Engineering

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Nicholsons is leading the design of resilient metal seals, gaskets and complementary components to the Aerospace, Automotive, Energy and Processing industries. The level of innovation is demonstrated by the large number of products and designs that Nicholsons has patented and supplied throughout the world. These form the core of our seals & gaskets business.

SBAC Approved CorruPlus ‘Corruplus’ Seals: AS42700 - AS42799

‘Corruplus’ Seals or ‘Gaskets’ are a patented, SBAC (Society of British Aerospace Companies) controlled aerospace Metallic Seal.

Nicholsons are the original designers of this acclaimed aerospace resilient metal seal.
100% Acceptance Tested ‘Corruplus’ are designed to have ultra-low clamp load, resilience after long term exposure to high temperatures, and be suitable for fire-proof operation. Originally designed for Concorde, they are in use in civil and miltary applications around the world.

Every ‘Corruplus’ seal is tested on our approved SBAC test-rigs as per the TS104 Production Acceptance Test.

Standard Product or Bespoke Design?
A Customer's sealing problem can sometimes be satisfied by one of our standard products (see our catalogues). This is often the case if the Customer is able to accomodate within their hardware one of our standard products, and the operating environment falls inside standard envelopes of pressure, temperature, operating compression etc. If you have reviewed our catalogues and are still unsure whether a standard product is for you, then please contact our Engineers who would be glad to review your requirements.

Certain factors might mean that a standard product is not a suitable solution: • the dimensions of the sealing cavity are highly irregular
• the environmental conditions are very arduous
(e.g. extreme or large cyclic changes in temperature or pressure)
• the cavity changes shape considerably during assembly/operational cycles
• the fluid to be sealed is aggressive
• the mating hardware has a poor surface finish, is segmented or has other irregularities
• vibration or movement is present
• leak rate must be highly controlled
• fatigue or creep life is a particular issue

With non standard applications, it is often the case that Nicholsons Engineers are able to rapidly develop a suitable solution with appropriate modifications to one of the standard designs using the appropriate tools and techniques.

Engineering Tools & Techniques
Long experience of applying proven designs to Customer's applications using the latest tools and techniques ensures the best product design for job. Nicholsons' Engineers use a combination of experience, engineering calculations, Finite Element Analysis and Computer Aided Design, sample manufacture and physical testing to ensure that a Design is fit for purpose before it ever goes to manufacture.

Engineering Calculations
Seals and gaskets live in the real world. The first task therefore is not to start modelling or drawing, it's normally to assess the Customer's hardware, identify the intended geometry, and determine issues such as tolerance stack-up and variation.

Finite Element Analysis
Nicholsons use ANSYS Pro Structural to carry out full non-linear, large deflection Finite Element Analysis (FEA) of products in their intended application. Temperature, pressure, compression and relaxation are most frequently modelled. We have developed parameter-driven scripts which mean that the same, rapid, best-practice method of modelling is used each time.

The screen shots to the left show a very basic FE analysis of a C Seal, with stress, strain and load-deflection as the output. The design can be optimised to produce the appropriate contact force within the material limits during the design stages before parts ever get made.

More complex analysis can be used to determine the effects of fluid pressure, modification of part geometry, cavity relaxation, and cyclic loading on part fatigue life. Not only can the structural capability of the part be assessed, but risk of catastrophic leakage can also be determined.

We have developed our FEA capability through commissioned directed research by the top universities, FE software manufacturers and consultants, our Customer's expertise, and our own, internal research. We are confident that our FE modelling produces a better design solution, faster.

Simple C Seal Geometry
Deformed Part - Stress Plot
Deformed Part - Strain Plot
Load Deflection Output

Physical Testing
An FE model that has not been Verified and Validated is worse than useless - it could even lead to making the wrong design decisions. We rigorously test our developing modelling capabilities so that we continue to tie our structural analysis back to the real world.

Stress plot of compressed multi bellow sigma seal

Nicholsons have a dedicated test house as part of our UK facility, specialising in the structural and fluid testing of our parts. We can evaluate high pressure sealing capabilities (of particular use for the Oil & Gas industry). Load deflection test rigs are used to verify structural models and determine impact on aerospace hardware. For more particular test requirements (e.g. hot aviation fuel testing), we work with accredited third party test houses.

Sealing performance comes from the combined integrity of Nicholsons' seals and Customer hardware. When Validation testing for the intended application, Nicholsons typically work with the Customer to jointly design test programs, experimental rigs, and assess results.

Computer Aided Design To Rapid Manufacture
For the Customer, the culmination of the Engineering Design process is an issue controlled drawing. Nicholsons use AutoCAD for drawing release. Our Issue Control process is stringent, in-line with our ISO, AS and TS committments.

Close collaboration from the outset between Product Design & Engineering (PDE) and Nicholsons' Production Engineering (PE) and Tool Room (TR) departments means that the developed design becomes manufactured reality quickly and risk-free. In the development of non-standard products, these three Technical Service areas work closely together to ensure that the evolving design is achievable and able to meet the Customer's program committments. Complex assemblies and tools are modelled in 3D using SolidWorks, and designs communicated directly to CNC machines for rapid manufacture.

FE modelled design

3D solid model of part

We are always looking to develop our Product Design & Engineering capabilities and product range. Please contact Nick Green (Nicholsons UK Managing Director), or Richard McGrady (Nicholsons UK Design Engineering Manager) with your sealing problems.