Deep hole drilling for oil
Three scallops are initially gundrilled then milled by Mollart Engineering in titanium for oil and gas exploration tooling
Mollart Engineering won a contract to produce oil and gas exploration tooling components by rethinking the production process around deep hole drilling.
The components are used for extracting samples directly from the well face.
Normally the titanium components some 120 mm diameter by 700 mm in length, would be turned with each of the three deep 50 mm wide scallop-shaped profiles along the outer diameter of the component being milled using formed cutters as separate multi-pass operations to remove the quantity of tough material.
However, Mollart’s approach by its application team, drawn from its deep hole drilling machine tool and subcontract production engineers, involved the combination of their process expertise to develop the application around single pass gundrilling to remove most of the stock material
As a result, three holes 50 mm diameter are now gundrilled to form the root of each scallop with equi-spaced pitching through the length of the component at a penetration rate of 30 mm/min. The part is then loaded to one of the seven Mazak Integrex turn-mill centres installed at Chessington where the outside diameter is turned and in the same operation each scallop gap-milled to open up the form and blend in the sides of the scallop into the semi-circular radial form.
Said Neil Anderson, Subcontract Manager: “Due to the nature of the material and the volume of stock to be removed, by applying the gundrill process to create the bottom of the scallop we were able to decimate the production time that would be normally required to mill each form from solid.” He estimates due to the toughness of the titanium and the power and rigidity available on a milling machine, it could take between 20 and 30 passes to produce each scallop.
“With our process we also achieved a high surface finish in the bottom of the form which due to the contact area required with a milling cutter if it were milled from solid, would tend to result in variations in surface finish and size plus having to deal with significant levels of vibration, chatter and pressures on tool life.”
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