A good enclosure material must do more than survive the injection moulding process. In oil and gas applications, it may also need to tolerate years of outdoor exposure, contact with chemicals and seawater, and defined flammability requirements.
Dudley Associates is supporting an oil and gas customer with the development of a suite of P20 steel tools for a new enclosure system. The customer has strong knowledge of CAD design and tooling, but asked for support identifying a polymer capable of meeting the application requirements without creating avoidable manufacturing risk.
The challenge
The difficulty was not finding a material with one useful property. It was finding a practical balance across several requirements that do not always sit comfortably together:
- F1 outdoor weatherability and resistance to prolonged UV exposure
- A defined UL94 flammability classification at the relevant wall thickness
- Resistance to the chemicals and cleaning agents expected in service
- Resistance to any relevant solvents
- Performance when exposed to seawater or a salt-laden environment
- Dimensional stability and predictable shrinkage
- Suitable flow and processing behaviour for the component geometry
These requirements needed to be considered as a complete system. A polymer can appear suitable on a headline datasheet while still presenting problems at the proposed wall section, during mould filling or under the actual environmental exposure conditions.
“A polymer can look right on paper and still be wrong for the application. The material, component geometry, moulding process and operating environment all need to be considered together.”
Turning the specification into a material shortlist
Our role began by separating the application requirements into clear categories. Weathering, flame performance, chemical resistance, solvent resistance and seawater exposure were treated as distinct questions rather than grouped under a general description of durability.
This matters because the evidence for each property may come from a different source. UL94 and F1 classifications are linked to recognised listings and conditions. Chemical resistance data may be based on specific concentrations, temperatures and exposure periods. Seawater performance may require additional customer validation because it is not automatically covered by a broad chemical-resistance statement.
A Covestro PC/PBT blend has been identified as a potential route. PC/PBT can offer a useful balance of impact strength, chemical resistance and dimensional stability, but the exact grade, colour system and finished wall thickness must all be reviewed against the application.
“We can open doors to a wide network of material manufacturers and distributors, and their technical teams are the real experts in their polymers. Some of the most useful conversations happen when we bring the design engineer, tool designer, moulder and material specialist together. It means we can look at the material, component design, tooling and processing requirements as one complete system.”
Material selection cannot be separated from DFM
The material decision also affects the tooling and moulding process. Shrinkage, flow length, gate location, venting, drying and process temperature can influence both the tool design and the finished enclosure. For that reason, material selection is being considered alongside DFM and tool development rather than treated as a purchasing decision made after the design is complete.
This is particularly important for a suite of steel tools. Once steel has been cut, changes to sealing features, wall sections or critical dimensions can be expensive. Resolving the material and manufacturing assumptions early gives the project a more reliable route into sampling and validation.
Planning a demanding enclosure project
If your enclosure has to meet environmental, flame or chemical-resistance requirements, involve the material supplier and moulder before the design and tooling assumptions are fixed. Dudley Associates can review the application, material evidence and moulding risks as one development problem.
