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Completing nuclear decommissioning with a CNC gantry milling machine


Mirage Machines recently worked with a customer in the UK to help complete a nuclear decommissioning project.

A bespoke gantry milling machine with automated tool changing was created by Mirage which also included drive gearboxes, spindles and linear milling rails with high precision ball screws for repeatability and positional requirements.

The CNC controlled machine was also versatile for use in restricted access areas, and included combined machining applications such as pocket milling, drilling and tapping.

Video - gantry machine in action

Job Description

Mirage was presented with the problem of multiple machining applications using a single machine within an environment that excluded any access to the machine. The proposed machine had to be capable of providing pocket milling, drilling and tapping within an area of 1.0m x 3.0m.

A single access point for exchanging tool bits/cutters was available but very tightly controlled with handling by heavy duty industrial gloves only.

CNC controlled

As standard, the CNC controlling hardware had the facility for automatic tool changing which could be incorporated within the Mirage CNC milling machine. Through customer demand, Mirage engineered the machine using DC motors.

Pneumatics were only used for the tool changing actuators alongside a controlled exhaust vent, as use within such a controlled area could create potential air born complications.

A linear multiple tool rack was introduced to the machine in the vertical position to enable effective tool change over.To prevent the tooling within the tool rack falling out, spring loaded tool capture fingers were used.

Mill, drill and tap

The final challenge was to mill, drill and tap with a single spindle DC motor, with each activity requiring varying torque and rpm requirements. Tapping required a higher torque range than could be accommodated within a single DC motor, so CNC controlled thread milling was introduced.

The end result was full CNC control offering positional repeatability using a common datum point, working from a known tool rack position.

To further qualify the machine for remote operations, an infrared probe was fitted within the tool rack to seek and find the work area to be machined with all references feeding back into the standard CNC control.

Other projects

Mirage has also designed and manufactured gantry milling solutions for a number of customers aorund the world, for applications such as heat exchanger repairs, pump and motor pads, mill stands, ship building and turbine split lines.

For more information on Mirage's range of gantry mills, download the free Linear Milling Buyers Guide or Linear and Gantry Milling Case Study Pack.

Download the Mirage Machines Linear Milling Buyers Guide

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