Prototype seals and rapid sealing solutions

Developing a new machine, product or assembly often creates a sealing problem long before production begins. You may need a single O-ring for a test rig, a non-standard hydraulic seal for a prototype cylinder, a machined PTFE component, a custom seal housing, or a complete prototype sealing arrangement manufactured from a CAD model or drawing.

Sealparts provides prototype seals, custom sealing components and rapid sealing solutions for engineering development, testing and low-volume production. We combine more than 40 years of sealing experience with modern rapid manufacturing technologies to help engineers move from an initial concept to a working prototype — and ultimately to a repeatable production solution.

Prototype sealing is an engineering problem

A prototype seal isn’t simply a production seal purchased in a smaller quantity. During product development the priorities can be very different. An engineer may need to prove a sealing concept before the final material has been selected. A housing may still be changing. Operating pressures may not yet be fully established. The final production quantity might be unknown.

Sometimes the immediate requirement is simply: can we make something that allows us to test this tomorrow?

Sealparts approaches prototype sealing as an engineering problem rather than a component search. We can work from:

• CAD models and engineering drawings
• Dimensions, or an existing component
• Photographs and material specifications
• Operating conditions
• Failed seals and prototype assemblies
• Or simply a description of the problem

The objective is to identify the fastest technically sensible route to a functional sealing solution.

Prototype O-rings

O-rings are often the quickest and most economical way of sealing a prototype. Sealparts can help identify suitable standard and non-standard O-rings for prototype applications, including metric, imperial and specialist sizes.

• NBR (nitrile)
• FKM / FPM (fluoroelastomer)
• EPDM
• HNBR
• Silicone / VMQ
• FFKM
• Polyurethane

Material selection can be considered against temperature, pressure, chemical compatibility, friction, compression set, environmental exposure and expected service conditions. Where possible we will investigate whether an existing standard size can be designed in before recommending a fully custom component — which significantly reduces prototype cost and lead time. Search the O-ring tooling database by inside diameter and cross-section to check first.

Custom O-rings and non-standard sizes

Prototype equipment does not always conform to standard O-ring dimensions. Large diameter O-rings, unusual cross-sections and non-standard diameters can often be produced without committing immediately to conventional production tooling. This is particularly useful for:

• Prototype machinery and test equipment
• Large housings and pressure vessels
• Specialist valves
• Research equipment
• One-off engineering projects
• Legacy equipment modifications

Once the design has been validated, we can investigate the most appropriate manufacturing route for subsequent production quantities.

CNC machined prototype seals

Machining provides one of the most useful routes for producing prototype seals and low-volume sealing components. Rather than waiting for conventional mould tooling, certain seal profiles can be manufactured directly from suitable semi-finished materials.

• Hydraulic and pneumatic seals
• Rod seals and piston seals
• Wipers and scrapers
• Guide rings and wear rings
• Back-up rings
• Rotary sealing components
• PTFE sealing rings and specialist profiles

Machined sealing technology is particularly valuable during development because dimensions and profiles can be modified between iterations. Prototype A can be tested, measured and inspected; the design can then be changed before Prototype B is manufactured. That ability to test, learn and iterate is fundamental to effective engineering development.

Prototype PTFE components

PTFE and filled PTFE materials are widely used in demanding sealing applications because of their low friction, chemical resistance and broad operating temperature range. Sealparts can source or manufacture prototype PTFE seals, back-up rings, washers, seats, bushes, rings and custom machined components in virgin and filled grades. Depending on the application, alternative high-performance polymers may also be considered.

Engineering plastics

A sealing system frequently contains much more than the elastomeric seal itself. Prototype components can be manufactured from PEEK, acetal/POM, PA/nylon, UHMWPE, PTFE, filled PTFE and other specialist engineering polymers — used for seal carriers, guides, bearing elements, spacers, back-up components and bushes.

Rapid CNC machining

Sometimes the seal is not the problem. The part around the seal is. Prototype seal performance depends on the complete mechanical system: gland geometry, shaft or bore dimensions, tolerances, surface finish, alignment and the way the component is assembled.

Through specialist manufacturing partners, Sealparts can coordinate rapid CNC machining of prototype metal and plastic components alongside the sealing elements — seal housings, glands, pistons, shafts, carriers, spacers, adapters, test pieces, assembly components and prototype fixtures. Working from CAD data or drawings allows a sealing concept to move quickly from screen to physical component.

3D printed prototype components

Additive manufacturing provides another rapid route for evaluating a sealing system — prototype housings, assembly aids, fixtures and associated components before committing to conventional manufacturing.

Prototype injection moulding

Where a development programme requires prototype moulded components rather than machined parts, rapid tooling and prototype injection moulding can provide a route towards production. This is valuable where engineers need to evaluate components produced by a process close to the eventual manufacturing method. The correct approach depends on geometry, material, quantity, tolerance, testing requirements and eventual production volume.

Custom moulded rubber components

Some sealing problems cannot be solved with an existing O-ring or standard profile. Sealparts can source custom moulded rubber components and bespoke elastomer seals manufactured to drawing: custom rubber seals, diaphragms, gaskets, boots, bellows, bonded components, specialist mouldings and non-standard sealing geometries. During prototype development we investigate the most appropriate route according to quantity, material and tooling requirements.

Seal material selection

Selecting a seal material purely because it is familiar creates expensive problems later in development. The material needs to be considered against the actual application:

• Operating temperature, system pressure and pressure cycling
• Chemical media, fuels and oils, water and steam, gases, vacuum
• Friction, wear, extrusion and compression set
• Environmental exposure and cleaning processes
• Regulatory requirements and expected service life

The correct answer may be NBR, FKM, EPDM, HNBR, silicone, polyurethane, PTFE or a considerably more specialised material. Material selection should follow the application — not the other way around.

Prototype seal failure analysis

A failed prototype is not necessarily a failed development programme. It is information. A seal that leaks, wears, extrudes, twists, hardens or suffers mechanical damage provides evidence about what is happening inside the application.

• Incorrect material or chemical incompatibility
• Excessive temperature
• Extrusion and inadequate lubrication
• Incorrect surface finish or excessive friction
• Installation damage and pressure cycling
• Incorrect gland dimensions and tolerance accumulation
• Unexpected movement and contamination

The objective is not simply to replace the damaged seal. It is to understand why it failed before the next prototype is built.

From prototype to production

One of the most important questions in prototype engineering is often overlooked: if this works, how are we going to manufacture it? A component that is perfectly acceptable for one prototype may be uneconomic at 1,000 or 100,000 pieces.

Typical progression

The prototype is not the end product. It is part of the engineering process used to establish what the end product needs to be.

One seal, or a complete prototype sealing assembly

You do not need to arrive with a finished specification. A prototype enquiry might be for one O-ring. It might be a CAD drawing requiring a sealing recommendation. It might be an existing assembly that leaks. Or it might be an entirely new mechanism requiring the seal, gland, housing and associated components to be considered together.

Sealparts can bring together specialist seal manufacturers, rapid CNC machining, engineering plastics, PTFE machining, additive manufacturing and custom component manufacturing to develop a practical solution — looking beyond an individual part number to the complete sealing system.

Start with the problem

If you are developing a prototype, send us what you have: a drawing, a CAD model, a photograph, an old seal, an application specification, or a description of what you are trying to achieve. We will start there. Send an enquiry.

Sealparts Ltd — Engineering First.