One of nine subsidiaries of the Calder Group, Leeds Bronze Engineering (www.leedsbronze.co.uk) was formed in 1974 as a specialist producer of bronze bearings and bushes.

The company has continually invested over the years, and it is now the UK’s largest manufacturer in the field of specialist bronzes; it also offers a comprehensive sub-contract machining service for a wide range of materials and industry sectors.

Leeds Bronze has an extensive stockholding facility and maintains the UK’s largest stock of copper-based alloys.

These are mainly bronze alloys to European and USA specifications and cover the full range, including leaded bronze and phosphor bronze, as well as aluminium bronze.

These alloys are all fully certified and traceable, with ultrasonic testing included where applicable. The company is also a leading supplier of specialist bronze components to a wide range of industries.

These include oil and gas, which Leeds Bronze supplies via global oil-exploration companies and manufacturers of production equipment. These parts have to be dimensionally precise; they also have to withstand arduous operating conditions — including ‘down hole’ applications.

The company also supplies bronze bushes, bearings and material to OEMs and sub-contractors in the construction machinery industry. Components and materials are used in a variety of equipment, including excavators, loaders, material handlers and dump trucks.

Other industry sectors supplied with both components and bronze alloy materials include: marine, where aluminium bronzes are used extensively for their excellent resistance to seawater corrosion; defence, predominantly manufacturers of submarines and surface vessels; fluid control, via a wide range of valve and fluid-control manufacturers and their sub-contractors; and general engineering, where high strength coupled with resistance to wear and corrosion is required.

Power generation is another sector that Leeds Bronze supplies with its specialist bronze alloys. The company also makes bronze self-lubricating bearings with graphite or PTFE inserts.

These are available in a wide range of shapes and sizes for applications where conventional lubrication is difficult.

Machining capability

ISO 9001-certified Leeds Bronze has approvals from Federal Mogul and Rolls-Royce and a shopfloor area of almost 30,000ft²; it also has more than 20 CNC machines.

These include three- and four-axis vertical machining centres, a wide range of fixed-head and sliding-head turning centres, and grinding machines — along with CAD/CAM systems, CMMs and inspection equipment, as well as cleaning equipment.

The components that Leeds Bronze produces are diverse, as are the materials it works with; in addition to the bronze and copper alloys for which the company is well known, there are aluminium, stainless steels, Inconel, composites and Duplex, to name a few.

Components range from small parts just 2mm in diameter (and made in high volumes on a Citizen sliding-head lathe) to large valve components and spun-cast valve bodies, the largest of which are machined on the company’s latest large-capacity machines — a Massa Summit VL-1600ATC CNC vertical turning lathe and a Target QV 209 VMC.

Production manager David Wilson says: “Before we bought the Massa VTL, we were limited to machining parts up to 1.1m in diameter, which meant we were competing with a number of companies in the area.

“We knew that we had to offer a larger capacity, and this was our brief when we went to the MACH 2014 show at the NEC.

“We were looking for a robust machine at the right price; we also wanted one with a Fanuc control, for compatibility with most of the other CNC machines that we use.”

Show stopper

Based on what he saw at MACH 2014, Mr Wilson bought the Massa VTL from Milton Keynes-based Axe & Status (www.axestatus.com).

It had the specification he needed for the company’s current work; and witha swing diameter of 2,000mm, a maximum turning diameter and height of 1,800mm and 1,350mm respectively, and a maximum table load of 8,000kg, it also had the capacity to differentiate Leeds Bronze from its competitors — and attract a wider range of sub-contract work.

“With a 45kW spindle motor, the machine also offered the power we needed for our larger work, while linear scales on the X and Z axes gave us the 0.005mm accuracy we needed.”

To enhance Leeds Bronze’s capabilities and efficiency for the complete machining of large components, Mr Wilson next needed a substantial and highly productive VMC that could undertake demanding second-operation work — hence the visit to MACH 2016.

“Being more than happy with the installation, operation and reliability of the Massa VTL, we headed straight for the Axe & Status stand, where we were recommended the Target QV 209 VMC as the machine that best met our requirements; and while we looked at a number of similar products at the show, the Target was the right price and offered the power and rigidity we needed.

“Moreover, it was fitted with the Fanuc 0i-MF control we wanted, and we were able to specify an increase in the Z-axis height to 1,150mm, giving us the room we needed under the spindle to accommodate the largest of the valves we machine.”

The machine has a geared BT50 spindle with a 22kW drive and a maximum speed of 6,000rev/min, a 32-tool ATC, through-spindle coolant, Heidenhain linear scales, a Renishaw OMP 60 workpiece-measuring system and a chain-type chip conveyor.

In conclusion, Mr Wilson says: “These latest two machines from Axe & Status, which has provided good support and been easy to deal with, have given us the capacity and capability to also serve the maintenance, repair and overhaul sector, which requires the refurbishment of high-value one-off components.”