Installation of a CNC lathe and a horizontal machining centre has provided significant productivity and flexibility benefits for a workholding equipment manufacturer.
Installation of a Daewoo Puma 12L CNC lathe and an ACE H400P horizontal machining centre from the same Korean manufacturer has provided significant productivity and flexibility benefits for workholding equipment manufacturer, Thame Engineering, located in Long Crendon, near Aylesbury. The ACE H400P has proved to be around 40 per cent more productive than the vertical machining centre that it replaced, and is equipped with Thame's own design of high capacity workholding system. Likewise the Puma is much quicker and easier to set up than its predecessor and provides improved finish and accuracy.

UK agent, Mills Manufacturing Technology, supplied both machines.

Thame Engineering is a leading supplier of standard and special chuck jaws as well as specialist workholding solutions for machining applications.

Its major strength is in development of 'smart' clamping solutions, some of which use vacuum or freezing techniques, for lathe-based machining of irregularly shaped components.

An innovative feature of some of these is the capability to reposition the workpiece in- cycle, thereby maximising single set-up productive capability.

In one instance a clamping solution developed by Thame, which allows the vacuum clamped plastic component to be rotated through angles up to 20 degrees in situ, has enabled a manufacturer of surgical prostheses to cut lead-time from around seven days to three-and-a-half minutes.

This astonishing reduction is a result of the fixture eliminating the need to leave the part to stabilise to size after machining.

Said David Handley, Thame's Technical Director, 'Our business is divided roughly 65:35 between supply of standard soft jaws and bespoke workholding solutions.

As well as chucks from 20mm to over 2000mm diameter, the specials side also embraces development of fixtures for prismatic machining applications.

Long Crendon is the main site but we have subsidiary companies in Bremen, Germany and Chicago, USA, with exports accounting for around 35 per cent of sales.' Machining requirements range from batches of two or three components up to around 400-off, so flexibility is highly important to Thame.

The company regularly works with machine tool suppliers on turnkey solutions for end users so the ability to fast-track production of components is essential.

Equally, production of standard jaws demands efficient machining methods so that the products remain cost competitive.

'We have around a dozen CNC machines of various types,' Handley explained.

'In addition we maintain a number of conventional machines for 'jobbing' work.

When we acquired the Puma CNC lathe it was as a direct replacement for a fairly antiquated NC lathe.

One of the key attractions of the Daewoo machine was its large swing.

We can turn over 550mm diameter on the machine, providing capability to turn jaw sets that are destined for use on vertical turning lathes.' Peter Mason, Thame Engineering's Managing Director, commented, 'We felt that the machine offered very good value for money as it is capable of tackling a wide range of work.

The integrated setting probe makes tool set-up straightforward while availability of constant surface speed ensures much more consistent finish compared with the old machine.

Although we bought the Puma for chucking we can use it for bar work utilising our own bar pulling device for batches of up to 400 components.' As with the lathe, it was capacity that persuaded Thame to invest in its Daewoo ACE H400P horizontal machining centre.

Whereas the Puma is used for a wide range of work, the machining centre has a more production-oriented role.

It was the 500kg table load of the ACE machine that particularly recommended it, which Handley said was considerably higher than the capacity of other machines he looked at.

'When we design fixtures for customers' machining centre applications we aim to maximise the number of components that can be mounted,' Handley continued.

'In this way the productivity of the machine is enhanced.

We originally used a vertical machining centre to produce the soft jaws but the horizontal machine provides much better access to the component for machining as well as improved control of swarf.

It also has through-tool coolant to maximise drilling performance.' Each of its two pallets is equipped with a four-sided tombstone fixture with clamping positions for twelve sets of jaw blanks.

Each face of the cube can accommodate different components if required.

Once loaded, the machine performs two operations on each component; serrations are machined in a separate operation to complete the component.

'Use of the ACE H400P has provided improvements in both productivity and quality,' said Mason.

'When we made these parts on a vertical machine they had to be chamfered manually but this step is now included in the CNC program.

Part of the machine's productivity advantage arises from being able to set it to operate unmanned between shifts and the fact that it does not need to have the operator in attendance other than to load/unload and set-up.' In fact the performance of the machine has been good enough for Thame Engineering to invest in a second, identical machining centre to boost capacity on standard jaws.

'We have been very satisfied with the performance of both Daewoo machines,' Handley concluded.

'In addition, the service from Mills Manufacturing has been very good and the training has been excellent.

Our purchase of a second HC400 is attributable to this, combined with operator familiarity and the fact that there appears to be no alternative that is more suitable for our purposes.'