Adam Howard, Director at Seals Direct
This week, Manufacturing Quality had the opportunity to sit down with the Director of Seals Direct, Adam Howard. The rubber seal, moulding, and gasket supplier discussed the quality control complications that rubber manufacturers face, the latest innovations that have helped alleviate these difficulties, and the importance of dimensional accuracy in quality assurance. Additionally, Howard also revealed what's next for Seals Direct.
MQ: First off, could you provide us with a general overview of what Seals Direct specialises in?
SD: Seals Direct works with original equipment manufacturers and end users in the supply and production of rubber seals, mouldings and gaskets. Our products are commonly used within the automotive, engineering, marine and retail industrial sectors.
Our experience allows us to identify, source and manufacture standard and bespoke rubber sections for a wide range of sealing, cushioning and edge protection applications. This includes window seals for classic vehicles to watertight door and hatch seals for use on oil tankers and Naval ships.
We can supply small quantities or continuous high-volume products in a large range of materials. This includes EPDM, Neoprene, Nitrile, Silicone and PVC. We also have the facilities to prototype 3D printed sections using a flexible rubber compound. This eliminates the need for tooling and minimum production runs until the design is tested and approved.
We have also built an in-house design team that is able to work with clients to design and develop bespoke rubber seals. This team is also able to reverse engineer and manufacture existing sections that are no longer available.
MQ: In rubber seal manufacturing, what do you find to be the biggest challenge when it comes to quality assurance? And how do your quality control measures help alleviate this issue?
SD: The biggest quality assurance challenge in rubber seal manufacturing is ensuring consistent dimensional accuracy. As the majority of our extrusions are being manufactured for a particular application, they must adhere to precise dimensional tolerances to ensure that they function correctly. Any deviation may result in an improper seal, leading to leaks or reduced sealing performance.
Most of our rubber products are extruded using an extruder and extrusion die. This extrusion process pushes the raw rubber compound through the die which, along with temperature and pressure, extrudes the required shape. As rubber is a flexible compound it pulses as passes through the extruder. This pulsing, along with being a flexible material, makes the material hard to control and can cause discrepancies in the final product’s dimensional accuracy.
Another challenge with quality assurance can be seen during the curing process which hardens and strengthens the extruded section. Depending on how this is achieved, this process can occasionally cause issues that affect the straightness of the final section. This is often seen when rubber products are cured in coils as some parts, such as vertical flippers, are set and may become distorted when taken off of the coil and straightened during installation.
We manufacture the majority of our rubber sections to an E3 tolerance, as specified by British Standards BS 3734 and International Standards Origination ISO 3302-1. These tolerances allow us to check the measurements of the extruded section against the original sample or drawing to identify any discrepancies with the final product.
MQ: In your opinion, has there been a modern innovation which has been game-changing in terms of quality control in your line of work?
SD: As the flexible rubber compound will always take the easiest route out of the extruder, it prefers to flow through larger parts of the extrusion die. For profiles, such as P sections which feature a large void and small protruding leg, the material will unevenly flow through the largest part. In this instance, this would be the top part of the P. By including flow plates onto the back of the extrusion die, we are able to divert a consistent and even flow of the material to every part of the extrusion die.
Ensuring that the final product is extruded correctly the first time has always been our preferred outcome. This ability to know exactly where to include the flow plate has been developed over years of experience and extensive trial and error. This has allowed us to foresee potential issues with the extrusion die and how the material may flow. The result of this is increased dimensional accuracy when compared to the tolerances set out by BS 3734 and ISO 3302-1.
Another recent innovation has been the inclusion of CV curing in extruders. In comparison to an autoclave cure, which is a separate machine from the extruder, CV curing involves curing the extruded section as it comes out of the extrusion die. This microwave oven immediately sets and hardens the rubber section, removing issues which may arise if the product is left or needs to be manually moved by an operator to a separate machine. This minimises the chance of distortion in the final rubber product.
MQ: What, if any, impact has metrology and measurement had when it comes to quality control?
SD: Comparing the dimensional accuracy of the extruded rubber section against the original sample or technical drawing allows us to identify potential issues with the final product prior to dispatching it to our customer. As discrepancies in the dimensions could cause issues with the sealing ability of the final product, we need to ensure it is within a dimensional tolerance.
MQ: What’s next for Seals Direct?
SD: Whilst a large proportion of our product range is manufactured to order, we also stock an extensive range of off-the-shelf products for general applications. These products, which include edge trims, rubber extrusions and window seals, are available in significantly lower minimum order quantities than products that are manufactured to order.
We are looking to significantly increase our range of off-the-shelf items to cater for customers looking for smaller quantities. These products will also be available with a shorter lead time, compared to bespoke items.
Whilst we are currently working to an E3 tolerance, we are continuously looking to improve our practices to supply extruded rubber products to a tighter tolerance.