You may be familiar with the background story of the Kavia 2K Bow Ball, an injection moulded product for rowing and sculling as we have already mentioned the product previously in this news blog but as we go into production in our West Yorkshire factory we also add it as a case study because it is a complex over-moulding of a 90 shore A >SEBS< core with a softer 40 shore outer.
Reasons for the product was fairly easy as Kavia’s product manager Iain Hill is an experienced rower and has first hand experience of the problems with bow balls with over 13 years of competitive rowing. They are: UV sunlight degradation causing the material to weaken, crack and tear easily.
Did you know most polymers lose half their structural performance after 5 years and then in the 6th year strength significantly drops in a matter of months.
Of course some materials have greater UV stability than others and you can also add-in inhibitors.
Rowing and sculling boat bow balls also get repeated loading from everyday use, a sculler often uses only one trestle and then rests the bows of the boat on the bow ball. All boat classes when returning to a landing stage often glance the bow ball in a sideways load. Finally the third issue is tearing around the mounting hole.
The Kavia 2K Bow Ball addresses all of these issues with the over-moulded design with a strengthened coloured core because it is a more dense material and also covered by the outer softer material. This protects it from UV degradation of the performance core and reduces tearing around the fixing hole.
With these design solutions comes challenges discussed under the project phases of design, tooling and manufacture.
Design
Iain Hill has a background in product design and clearly had a two-part concept solution in mind when creating a concept sketch and brief for our design partners Trig Creative in Leeds. Areas of design focus included: eliminating and sharp root radii as these can stress raisers, the engineering of inter-twinning core and outer for mechanical bond and performance, styling and brand message.
It certainly is quite unique to over-mould two soft >SEBS< materials but a key message was also to demonstrate there is a core and that it is connected to the main ball feature. This is done by three visible stripes giving a sporting message whilst also showing the centre stripe coming first like in multi-lane regatta racing. It is the white bow ball that is used as the identifier in photo finishes. Finally having a stylish design makes the product easily identifiable versus bland competing designs as well as allowing some colour branding for boat makers livery or club colours.
Tooling
Although there are no published figures of new boat sales worldwide we can’t imagine there are much more than 20,000 new boats per annum worldwide going into the market place but because boats lasts 10’s of years the installed market is huge. If you take the 41 countries that competed at the London 2012 Olympics for rowing with a conservative average of 400 clubs per country (UK has over 800 clubs) with 50 boats in each club gives a market of over 800,000 boats needing replacement bow balls at some point.
With the above assumptions in mind annual quantities are unlikely to be excessive and would not require multi-impression injection mould tooling versus market sales penetration progress so a 1+1 family tool that initially moulds the core first and then a turn-gate used for the second over-mould white outer. The core runs auto and can take advantage of Kavia’s lights-out running efficiencies, the over-mould is a manual process requiring an operator in the day shift. Kavia designed and manufactured the tooling in just 8 weeks.
Manufacture
Kavia anticipated there would be issues to overcome in manufacture in shutting out the three thin stripes, filling thin and thick sections, holding the core in position during over-mould stage and cycle time of the outer. Resolving these issues gives us great experience and makes the product more unique.
We have delivered our first order to our UK distributor and are seeking worldwide resellers and boat builders to put on their new boats. You may have read we nearly got our bow ball onto the Oxford Boat Race crew boat and need to get this sorted out for next years race. We will also be supplying Leander Boat Club so look out for the famous salmon pink on their bow balls at this summers Henley Royal Regatta.
