Product Details Supplier Info More products

Mollart Engineering has developed a high-precision, micro-deep hole-drilling solution for oxyacetylene gas cutting torch nozzles for its US customer.

The machine build contract to Mollart combines, in a single cycle, the deep-hole drilling of a 2.3mm diameter central stepped bore for gas feed by 75mm deep in the Terillium copper material.

This bore is then counter-bored to 3mm diameter by 50mm deep with a further six, 2mm diameter, through holes created for air feed.

These 2mm holes are set on a 12.4mm pitch circle (PCD) but inclined in a converging fan pattern towards the central bore to break out at the nozzle end on a 6.8mm pitch circle diameter (PCD).

In the Mollart solution, developed around its four-spindle Microdrill VDM, three additional axis movements giving tilt, PCD positioning and a rotary indexing motion have been integrated to the special control software that also incorporates independent tool monitoring.

There is also a programmable function that enables the hole pattern to be quickly calculated when setting a new part.

The fixturing, enabling 224 parts to be held on the table at the same time under the four spindles, also enables the drilling of the different hole diameters in the same part without reclamping.

The spindles are each run at 25,000rev/min and at a feed rate of 450m/min.

The vertical spindle Mollart Microdrill VDM has four high-speed, 25,000rev/min spindles that power the micro-diameter solid carbide gundrills, with through coolant feed, upwards into the components.

This technique maximises control over swarf evacuation with each spindle being driven at a penetration feed rate of 450m/min.

Following machining trials, all components were tested for burn pattern and were found to demonstrate an improved performance of up to 100 per cent over the previous method of production.

This was attributed to the high quality of the gundrilled hole generated by the Botek tooling that created a burnished surface from its precision ground carbide guide pads giving improved flows of both gas and air.

Once installed, the customer was able to reset the machines to accommodate the 75 different types of part in record times of between five and 15 mins.

Cycle times were proven at 19s for the six 2mm holes and 6s for the central hole, creating a further saving of 25 per cent on the cycle time originally calculated at quotation stage.

As a result, each machine is able to produce parts at a rate of 189/hour.

View full profile