Established in 2020, Wavecon is a Hartlepool-based provider of cable assembly solutions for subsea assemblies. The company supplies replacement cable harnesses and wired assemblies, through to producing custom-designed and -manufactured bespoke assemblies for specific applications.
Wavecon offers a range of encapsulation and moulding solutions, supported by an integrated 3D CAD and CAM, 3D prototyping, and CNC services. As part of this, Wavecon applies a variety of overmoulding techniques, including two-part moulding and low-pressure vertical injection moulding.
Overmoulding is used to form a watertight and strong mechanical seal around cable assemblies used in harsh environments, particularly sub-sea applications. The cable assembly is positioned within a mould and the overmoulding material is injected into the cavity. It is important that the moulding material adheres well to the surfaces, providing good shear and peel strength to cope with any movement.
Wavecon’s overmoulding process involves bonding to a range of different materials, dependent on the customer’s application. They include insulation made from polyethylene, chlorinated polyethylene (CPE), polyurethane, rubbers, and neoprene, many of which have low surface energies resulting in poor wettability and bonding. These substrates present an adhesion challenge.
Initially the company took steps to improve adhesion by abrading, and painting the surfaces with liquid primers, which are active chemicals in a solvent carrier. However, the use of primers introduced some issues, such as the wait time for the primer solvents to evaporate, which is further increased when repriming is needed.
In addition, because the company works with so many materials both for the cabling and the overmould, there were a lot of process variables, and the team experienced inconsistent results.
Paul Whitehead, strategic accounts manager at Intertronics, said: “After detailed discussions with Wavecon’s team, we recommended the piezobrush PZ3 handheld plasma surface treatment device to treat the outside of the cable before it is inserted into the mould. The device increases the surface energy of the substrate by altering the chemical groups on the surface to improve wettability and create bonding anchors on the surface.”
The Piezobrush PZ3 uses cold atmospheric plasma technology and therefore does not involve significant heat. The handheld device uses piezoelectric direct discharge (PDD) technology to transform low input voltage into high electric field strengths, dissociating and ionizing the ambient gas (usually air) into plasma.
Where conventional atmospheric pressure plasma treatment processes may require special gases or automated handling, the PZ3 is unique in that it is a handheld cold plasma device, enabling uncomplicated and manual optimisation of surfaces at a relatively low cost, on demand. The PZ3 requires no specialist knowledge to operate and is equipped with several in-built process control features that can be adjusted using a simple user interface, so Wavecon could easily tailor it to different applications.
Wavecon director David Stout said: “We did consider alternative plasma technologies, such as large ovens, but decided that the PZ3 would be easier to use, was more affordable, and would deliver quicker return on investment.
“We conducted extensive trials with different primers, different surface finishes, and with plasma pre-treatment and got good results bonding the polyurethane to rubber and polyurethane CPE cabling. We found that by abrading the surface and then treating with the piezobrush plasma pen, we could encapsulate the cables with a good, watertight join.”
The Wavecon team has since done extensive testing in a pressure chamber at 466bar, the equivalent of a depth of 3km, demonstrating high quality and excellent durability.
With the introduction of the PZ3, Wavecon was able to stop using primers in several applications. This means the team now uses fewer chemicals, which is better for operators, reduces the health and safety requirements for respiratory equipment, decreases risk, and is better for the environment. In addition, the PZ3 has helped Wavecon to decrease production time, as it has removed the wait time for primers to dry, as well as the need for repriming.
Stout added: “The PZ3 can do in five seconds what would previously have taken up to half an hour, further reducing lead times for our customers. We pride ourselves on quality, and the PZ3 has helped us to develop a reliable process that delivers quality every time.”
