DS-NOV22-PG32_Layout 1 18/11/2022 10:36 Page 1
FEATURE
FASTENINGS & ADHESIVES
ImprovIng overmouldIng adhesIon
Looking for a way to optimise the adhesion of the overmoulding material to
cable sheaths, a provider of cable assembly solutions turned to Intertronics…
A
s a provider of cable assembly solutions for subsea assemblies, Wavecon offers a range of services – from the supply
of replacement cable harnesses and wired assemblies, through to fully designed and manufactured bespoke assemblies for specific applications. The company offers a bespoke and OEM
range of encapsulation and moulding solutions, supported by integrated 3D CAD and CAM, 3D prototyping, and CNC services. As part of this, it applies a variety of overmoulding techniques, including two-part moulding and low-pressure vertical injection moulding. From the outset, the team decided to build
an end-to-end manufacturing process to retain 100% control over product quality.
BuIldIng an overmouldIng process
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 peal strength to cope with any movement. Wavecon’s overmoulding process involves
bonding to a range of different materials, dependent on the customer’s application. A wide variety of materials are used in the subsea cable market, including 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.
2 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 re-priming is needed. 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.
FIndIng a solutIon
Wavecon was looking for a way to optimise the adhesion of the overmoulding material to the cable sheath to achieve a good bond strength and perfect the process. 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 a handheld cold plasma device, enabling uncomplicated and manual optimisation of
3 DESIGN SOLUTIONS NOVEMBER 2022
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. David Stout, director at Wavecon,
commented: “After speaking to Paul at Intertronics, learning about the available options from its whitepapers and hearing about Intertronics’ experience with past applications using the PZ3, we decided to trial it in several applications. 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 466 bar, the equivalent of 3000 metres deep, demonstrating high quality and excellent durability.
a qualIty process
With the introduction of the PZ3, Wavecon was able to stop using primers in several applications. This means the team now uses fewer chemicals. 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 re-priming. 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.”
Intertronics T: 01865 842842
www.intertronics.co.uk
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60
