Customised vices provide flexible workholding

Twin customised Kurt vices (vises) at Haberman Machine accurately centre two heavy workpieces over a machine pallet for extra rigidity while facilitating aggressive metal removal.

The new workholding setup has replaced a much slower setup process on vertical machining centres at Haberman.

In the new setup, the matched Kurt vices both have 21in jaw openings for clamping vertically steel workblanks weighing more than 100lb.

The setup is designed for use on two different sized machine pallets, thus giving Haberman flexibility to machine a wider range of large parts.

By reducing setup time, throughput is increased, providing a good example of how important, well-designed flexible workholding is to get the most productivity out of expensive machining centres.

Being able to centre and clamp the large workpieces vertically and with rigidity is key to high metal removal rates so that the machine spindle can effortlessly hog out large amounts of material at the centre of gravity.

With over 60 years in the precision machining business, Haberman Machine knows the importance of workholding and makes use of it to increase productivity.

It uses dozens of preset tower and vice fixtures for quick setups on repeat projects.

Its work covers the complete spectrum of parts, materials and customers, from tiny medical devices to large defence components.

All require precision machining with relatively short run quantities, frequent setups and the use of modular workholding.

The components at issue here are machined out of 8620 steel alloy and are used in a mould system designed by Nesstech Concrete Moulds and built by Haberman.

The mould system utilises different sized plates that are movable with a gear drive assembly to produce different sized architectural wall, paver stones and retaining wall blocks.

These precision-machined mould components are large and heavy with the 30in x 40in workblanks.

Machining these components requires robust workholding to align and rigidly hold the workpieces.

Because of their size and weight, operators are challenged to position and clamp these mould components in the machine.

Workholding that makes this job easier and faster is a welcome addition by the machine operator.

'Standard vices mounted on a tombstone really didn't work for this type of machining application,' said Scott Ness of Haberman Machine.

'We needed a setup that could accommodate machining these long parts in a vertical position (z axis) with enough clearance for machining on both sides (xy axis).

'We needed workholding that was flexible for use on two different machines and was relatively easy for operators to handle.

'We've been a Kurt workholding user for over 25 years so we checked with them to see what ideas they had.' The vices Kurt recommended were two 8in-wide, extra-long, pull-type, single-station vices.

The reason for this approach is that the setup is flexible and provides the part capacity and rigidity needed, plus it's an easier and less expensive solution compared to a custom fixture.

In addition to a 21in jaw capacity, these vices are designed to mount without disassembly or modification to two different horizontal machining centres with different size pallets (Mori Seiki MH63 - 630mm pallet and Niigata SPN 50-HO - 500mm pallet).

To accomplish this, the two Kurt vices are bolted (six 1/2in Allen nuts) and dowelled back-to-back.

All sides of these vices are machined accurate to 0.001in so that they align when mounted back-to-back.

Bolted together, the two vices are mounted on a 500mm base plate, which then mounts to the 500mm machine pallet.

A 630mm subplate allows mounting directly to the 500mm base plate, which can then be mounted to the second machining centre.

A 2.25in high riser is also used in the setup to achieve the desired spindle clearance for both machine setups.

The extra-long, pull-type Kurt vices used in this application are specific to heavy duty workholding.

They are made of 80,000lb/in2 ductile iron to provide stability so that possible chatter or vibration is eliminated from the machining process.

Delivering up to 12,000lbf precision clamping force, Kurt's Anglock vice design helps to automatically position the workpiece in the vice jaws.

As clamping force is applied, the mould workblank is pushed down and onto the vice base, which also aligns it accurately.

The Anglock design resists any tendency for part lift during machining operations.

This pull-type clamping design insures high precision and repeatability.

'The machine operator uses an overhead crane to lower the workblank into the vice clamping area,' said Ness.

'Once moved into the open jaws, the vice is clamped manually.

'With this setup, there are no machining clearance issues as there would be using a tombstone setup.'.

Back to top