Two new bar magazines capable of increasing the productivity of an automatic turning machine by typically 10 percent, but conceivably by as much as a third depending on the application, has been introduced to Britain and Ireland by A and S Precision under its agency agreement with the German manufacturer, FMB. Called Turbo 5 - 42XT and 40 - 100XT, they have been added either side of the pre-existing 10 - 65 XT to provide a full range of magazines for feeding bar up to 100 mm diameter to a linear accuracy of ñ 0.02 mm. This is in stark contrast to most bar magazines whose feedout tolerance is of the order of ñ 1 mm.
Substantial savings in cycle times and hence manufacturing costs result from not having to feed forward to a stock stop or tool as with conventional equipment.
Moreover the use of stops is eliminated, freeing up a tooling station.
The accuracy of the magazines is not affected by the feed speed since the drive is delivered using a ballscrew rather than a chain drive.
The following is an actual example of savings which have been achieved.
A 60 mm long steel mandrel turned from 38 mm diameter bar, requiring boring, profile turning and threading but no driven tool work, was previously produced in a cycle time of 76 seconds when fed out to a stock stop.
The same component can be produced in 67 seconds when the lathe is fed by an FMB Turbo 10 - 65 XT, showing a productivity increase of 11.8 percent.
Cost saving was nearly 6.5 pence per piece part at the German factory which carried out the comparison, resulting in an annual saving of over £10,000 based on two-shift production.
If a component needs only a short machining cycle, feedout becomes a higher proportion of the overall throughput time and so the productivity increase is even greater.
Clearly the converse is also true.
The magazines incorporate an oil-filled channel in which the bar rotates and it is able to feed round, square or hexagonal stock, bright or black.
Bar within a wide diameter range can be accommodated within one size of channel, that range being increased if straight bar is used.