A specially designed electric furnace from Carbolite is being used by Hope Technology to heat treat brake discs for high-performance road and mountain bikes.

 

Hope Technology manufactures high-performance cycle components, including disc brake systems, wheels, hubs, seat posts and lights.

The equipment, which is often manufactured from stainless steel, titanium or aluminium, is used by leading competition riders and widely exported.

 

The company manufactures stainless-steel brake discs in 25 different standard designs and many bespoke designs to customer specifications.

 

Diameters range from 140mm to 203mm, with a standard finished thickness of 1.8mm.

 

The finished product must be within 0.01mm parallel in order to ensure consistent, smooth braking performance in extreme conditions.

 

Previous use of pre-hardened sheet and induction heating on unhardened material had both failed to achieve the required specification.

 

The discs are initially laser cut from 2mm-thick stainless steel sheet before the detailed machining is performed on a CNC milling centre.

 

The discs are then linished to remove burrs before being heat treated to harden them.

 

To perform the hardening process, an actuator pushes one disc at a time from a stack of approximately 50 into the Carbolite slot-type furnace, which is held at a temperature between 950C and 1000C.

 

Discs are heated for 60 to 90 seconds and then pushed into a water-cooled platen to flatten and cool them.

 

The entire process is automated and continuous, provided that the stack of unhardened discs is replenished.

 

The furnace temperature and the length of time each disc stays in the furnace are adjusted to suit the dimensions and amount of material involved.

 

Control is provided by a high-precision PID unit mounted on the safety cage round the equipment and linked to a thermocouple within the furnace chamber.

 

A separate temperature controller and thermocouple prevent over-temperature conditions.

 

For quality control of circuit boards in cycle lamps and to reduce adhesive curing times, the company uses a Carbolite oven with a maximum temperature of 80C and an internal capacity of 65 litres.

 

Heating batches of lamps for 20 minutes to 70C in the oven has proved to be an effective method of identifying potentially faulty circuit boards before final assembly.