Unique single-source machine tools provider PTG Heavy Industries of Yorkshire has designed and manufactured two Binns & Berry lathes for producing the critical components for the world’s largest mining shovels, each capable of loading a 500- ton dump truck in just three minutes.

The order was secured against stiff competition from German and Italian manufacturers and the machines have now been installed in the United States and China.

The challenges presented to PTG were many and complex, involving multi-axes, heavy duty milling and drilling, a massive thread and $50,000 forging. Total precision and a high quality surface finish were also very high on the customer’s agenda.

The machines in question, two special Binns & Berry VT7 twin saddle lathes, will be used to manufacture major components such as the main shipper shaft, centre gudgeon and crawler drive shafts, the machines’ unique specification having been developed by PTG in close collaboration with the customer.Three into one will go

The key benefit that the machines will give the customer is that of being able to manufacture the components on a single machine where previously no less than three different machines, a lathe, horizontal boring machine and a milling machine, needed to be deployed for the manufacturing of the shafts, the largest of which weighs in at 11 tons.

The unique specification means that the machines can execute the turning, keyway milling, threading, drilling, tapping and thread milling of one and a half UNC holes x 5.5 inches deep in single set ups, allowing the component to be machined complete on just one machine, eliminating multiple handling operations and so significantly reducing manufacturing time. In fact, with the elimination of multiple handling and the necessity of transport to a second location, cycle time was more than halved from 65 to 32 hours.

The specification of the new machines also enabled inspection online, eliminating the need for a separate validation process. While intelligent motor and drive power utilisation were incorporated along with tool monitoring.

In more depth

In more depth, the machines were supplied with massive 12- position VDI 80, 22kW driven tool turrets (one to each saddle) providing full heavy duty mill turn functionality.

One of the key run off criteria involved developing special threading routines to cut 1 inch pitch Acme threads on a 26- inch diameter, including milling special starts and exits to the thread flanks. The run off components were successfully machined at PTG’s Elland facility and the £22,000 forgings finish machined, inspected and used as production components. The technical specification of the machines is as follows:

Swing over bed: 1200mm.
Max turning dia.: 900mm.
Distance between centres: 9,000mm.
Unsupported weight carrying capacity between centres: 15,000 kgs.
C axis: Continuous path with .001 degree positioning accuracy
Y axis: +/- 150mm. above and below centreline
S1: Main spindle 88kW.
CNC system: Siemens 840D solution line
LH Carriage X1, Y1, Z1 & S2
RH Carriage X2, Y2, Z2 & S3
Steadies: Rohm Self Centering Rohm with 660mm. capacity and 600 to 900mm. capacity manual steady

One precision machine, a one-stop shop

Just as PTG Heavy Industries, as we’ve seen above, can help its customers to simplify and streamline their manufacturing process by using just one machine instead of three, so, as a one stop shop for machine tool solutions, it can also simplify the process of machine tool selection and provide process improvement.

PTG’s unrivalled knowledge and expertise in the design and manufacture of heavy duty lathes, grinders and FSW technology ensures that customers’ requirements and expectations are not merely met but exceeded across a wide range of industry sectors, including steel, aerospace, marine, railway and heavy engineering.

PTG Heavy Industries also provides re-engineering, retrofit and spares and service for most machine tools, ensuring total support for customers.

To ensure optimum quality control, all engineering design, build, testing and commissioning are performed in-house with the Elland manufacturing facility ideally suited for building and assembling large machine tools with the capability to handle 60-ton component weights in a single lift. One of the largest in-house slideway planing and grinding facilities in Europe confirms the company’s status as a true one-stop machine tools solutions provider. While the total integration of the group’s resources makes for design and build facilities unrivalled anywhere in the UK.