We spent the day at Dymag to see how composite wheels are made. This is what we found out. Thanks to all at Dymag for their time, the cups of tea and the chocolate.
Dymag wheel designer, Mike Wilson, who has been with the company for most of his working life, works out all the engineering aspects of a wheel using CAD software before any manufacture takes place.
TThe design software allows Mike to simulate the real world stresses to which a wheel will be subjected. Here we can see the stress exerted on a wheel as a result of cornering forces.
The main body of the wheel starts life as pieces of woven carbon fibre sheet which are cut to shape ready to be laid up by hand into a two piece mould. The individual strands of carbon fibre are D-shaped in section which gives optimum bonding.
We cannot show you this bit as the actual lay up procedure used by Dymag is a closely guarded secret. Craig Butler (pictured) was working on a wheel when we arrived. All lay up is done by hand. The process is similar to that used in the making of fibreglass components.
Once the lay up is complete, the two halves of the mould are bolted together. The resulting pressure ensures proper bonding and uniform thickness. The initial curing takes place overnight and is done at a controlled room temperature. Further curing is then carried out at 100 degrees Centigrade once the wheel has been removed from the mould.
When the wheel is removed from the mould, the exposed edges are razor sharp. After heat curing, the blanks are machined to remove all of the flashing which results from the moulding process. Once cured, carbon fibre is extremely hard and the tools required to succesfully machine it are expensive.
Alloy centres, like the component shown here, are prepared and bonded into the machined blank. They will provide the location for the sprocket and brake disc carriers.
Andrew Moore prepares to load a wheel into the lathe so that the alloy centre can be machined true to the wheel rim and be prepared to accept the carriers (disc carriers in this case as it is a front wheel)
After machining, the centre is checked for truth using a Dial Test Indicator (DTI). Look closely and you can see the register machined into the centre to provide a positive location for the brake disc carrier.
CAD software is used to design the brake disc and sprocket carriers. Pictured here is the on-screen rendering of a rear sprocket carrier, which, like the brake disc carriers, also serves to house wheel bearings.
The carriers are machined from HE 30 aluminum alloy which is highly corrosion resistant, has excellent elongation properties and is commonly used in highly stressed applications, including beer barrels.
Machining aluminium alloy at high speed generates a great deal of heat. Cutting fluid (suds) are used to both lubricate and cool the tool and the work. This is what happens to the tool if it gets too hot.
Andrew Moore at the controls of the HAAS CNC mill. He is resetting the mill to the exact line of code (from 5000) so that he can resume the machining process from the point at which it was temporarily paused.
Disc and sprocket carriers and the corresponding lumps of HE 30 aluminium alloy from which they are machined. Modular construction makes it relatively straightforward to build a wheel for any motorbike.
A sprocket carrier is pressed into the centre of a rear wheel. The blue stuff you can see around the circumference of the centre is the adhesive used to bond the carrier to the centre. It’s strong glue. Once bonded, the carrier can withstand a force of 12 tons per square inch.
The disc and sprocket carriers also serve as wheel bearing housings. Here a wheel bearing is being pressed into the brake disc carrier of a front wheel. Making a composite wheel is labour intensive. Much of the work is done by hand and a single wheel takes a full person day to produce
Wheel assembly technician Simon Hardisty (right) and designer Mike Wilson with a finished composite front wheel. Simon will be responsible for assembling the wheels which will be fitted to the Enigma 1050. Light, beautifully made and British – Dymag composites are the perfect choice for our project.