Working in conjunction with Mollart Engineering’s tooling operation (www.mollart.co.uk) to re-engineer the production process for a range of brake master cylinders has seen Carlisle Brake & Friction (CBF) (www.carlislecbf.com) slash its manufacturing costs — so much so that the company has initiated expansion plans that could see its current annual output of 100,000 master cylinders double during 2016. Moreover, some 90% of this output will be exported.

The re-engineered processes have resulted in a massive cut in labour costs, reduced machine setting times and lower tooling costs; there is also less stock and work in progress — and lead times are significantly shorter.

Chris Cudlip, operations manager of the Pontypool operation, said: “We worked very closely with Mollart engineers to adapt our bore-finishing process around reaming and roller burnishing; doing so has allowed us to move from multi-operational sequences to cell-based machining that uses single-cycle cutting. As a result, we are now a ‘world-competitive’ supplier.”

CBF produces brake actuation systems for a number of industry sectors, including off-road, agriculture, construction, materials-handling, aerospace, defence and motor-sport. The company makes two basic versions of master cylinder: a single-pedal unit (CV) and an un-boosted compensating unit (CCV).

Both have a common series of bore sizes but different configurations of connector ports for single-pedal or twin-pedal steer-turn applications.

Prior to introducing its re-engineered pro-cesses, CBF was using more-traditional high-volume production machining based on three six-spindle Wickman multi-spindle chucking autos, two variants of Wavis centre-column special-purpose machines (one with vertical spindles, the other with horizontal spindles) and a six-spindle Nagel honing machine that pre-finished and then deburred the bore of the grey cast-iron components.


While this process was ideal when introduced some years ago, the machines were becoming a liability, with increasing maintenance problems; lost production through service and breakdown was also adding cost to the products, as were the setting times and work-in-progress necessitated by the multi-machine/multi-process methods being used. The cost of solid-carbide tooling was also a concern.

Initially, CBF focused on improving the tooling. However, when Mollart was called in — because of its expertise in deep-hole drilling, boring and bore finishing — it suggested that CBF should switch from drilling, boring and finish honing to drilling, semi-finish reaming and roller burnishing, adding that this could easily be combined with the machining of other features on a four-axis vertical machining centre.

Following trials based on Mollart’s suggested process, the first four–axis VMC was installed; and with tooling supplied by Mollart, sample parts were produced for extensive endurance testing and customer approval. The change of process was a complete success.


The improved method now involves four VMCs with four-axis units working in a cell, with tooling that includes a Mollart-supplied Micro-Reamer. This has a single blade with two carbide guide pads strategically placed to absorb the cutting forces; blade adjustment is achieved via two screws acting on an adjustment wedge.

The reamer is set to leave stock for the following burnishing tool, which uses cold working to compress ‘surface peaks to valleys’, thus taking out any tool marks and minor irregularities. The reaming is carried out at 1,193rev/min and a feed rate of 200mm/min. The Elliott multi-roll internal roller burnishing tool from Mollart is run at 450rev/min at a feed rate of 450mm/min; it achieves a consistent 0.025mm size tolerance and a 0.3µm CLA surface finish, which is half that specified on the drawing.

CBF technical manager Paul Hadley says: “The process is totally consistent; and by using the latest electronic gauging system, we are able to confirm the ability of the process to maintain size and — in particular — roundness within 4µm. Rejects are now almost non-existent. Important in the process is the high oil content of the coolant we use — plus the fact that we have high-quality filtration and change filters every six weeks. Both contribute to high levels of quality and good tool life.”

Mr Hadley says there are five variants of cylinder: 5/8in, 3/4in, 7/8in, 1in and 11/4in, adding that a major changeover takes just 2hr. “Previously, each of the three Wickmans would need two shifts, the Wavis special-purpose machines 10hr and the Nagel hone 6hr. We can now work on batch sizes of 100; although with four VMCs we have the capability and flexibility to produce as few as 12 if required in an emergency. Previously, parts were made for stock, so WIP and lead times have been decimated.”

Summing up the savings made, Mr Cudlip says: “Largely initiated by the Mollart tooling that enabled the process change, labour input has been reduced by 60%, and we are achieving 98% labour efficiency; and whereas the old plant took up a quarter of our 5,500sq ft, the four VMCs occupy just 10% of our floor space.

“Moreover, we have completely de-skilled the process, and we have slashed our tooling bill, because we only have to change inserts rather than re-grind tools. Overall, we have a very effective single-cycle production operation, which has allowed us to not only secure production in the UK but also become very competitive in international markets.”

CBF in Pontypool is a division of the US parent company (headquartered in Solon, Ohio), which has 11 manufacturing sites around the world employing 2,000 people. Pontypool is the design centre for brake actuation products and the global manufacturing centre for hydraulic brake cylinders.

It employs 89 people and grew out of Girling Brake Products, which was formed in 1925. This company merged with Lucas Varity in 1996; following further mergers and acquisitions, it was taken over by the American business in 2005. With further expansion in mind, CBF acquired 2.3 acres of land adjacent to its factory earlier this year.