Portable milling machines are used for many different types of on-site machining projects throughout the oil & gas, power generation and petrochemicals industries.
For the on-site machinist, knowing in advance how the product will be mounted onto the job will not only help things run smoothly, but also deliver accurate results, and ultimately, save the customer both time and money.
So, what are the different ways that 2-axis and 3-axis portable milling machines can be set up?
Our examples below will give you an overview of the commonest methods.
The milling machine, or milling rail, as they are commonly called, is normally supplied with bolt holes which allow fixing either directly to the job, or onto other fixing components. Examples of these are as follows:
Mounting plates and brackets
Above Left: Brackets supplied as standard with the milling rail.
The mounting plates can play a significant part in the overall project. In many cases, it will need to be produced especially for the specific job and may be attached to the work piece using methods such as tack welding, or drilling and tapping. In the case of pump motor mounting pads, these can include a mix of steel and concrete.
Heat exchanger mounting plates
Above:Heat exchanger mounting plate
A more lightweight type of milling machine, such as the Mirage LMR range, are ideal for jobs such as machining division slots at the end of heat exchanger tubes. Tack welding is not appropriate in this case, so purpose made heat exchanger ‘tube sheet mounting plates’ should be used.
Chain clamps and ratchet straps
For fixing to pipework and other cylindrical items, a chain clamp can be wrapped around the pipe and the milling rail bolted onto it. For large diameters of over 1.5m, a ratchet/cargo strap can provide a more lightweight and satisfactory solution.
Switch magnets can be used to fix the milling machines to any steel surface, providing a means of fixing that requires no change to the work piece. These are bolted onto the milling rail and levers on each magnet lowered to secure the milling rail or gantry into position.
Gantrys for milling machines
Gantry systems are used when a large working envelope is needed. A gantry used with a 2-axis milling rail will provide a 3-axis solution. They can be mounted in both horizontally and vertically however, when using a rack feed type, the rails incorporating the rack should be positioned in the horizontal orientation.
Quick setting and fine adjusting
When installed into position, the milling assembly will need to be checked and adjusted to align it properly with the work piece. The extent to which this is done will depend upon each customer’s requirement, for example, a task to machine division slots in a heat exchanger tube will not need laser alignment. In situations like this checking and adjusting with a clock dial indicator will be accurate enough. Larger jobs, such as those using a gantry, will most likely need to be checked using laser alignment.
Adjusting the alignment of the milling rail is done using the M12 bolts on the mounting brackets supplied with the machine. See illustration below:
One method of aligning a gantry is to use adjustable wedges, like the example shown below. These are attached to the underside of each gantry rail and height adjustments made using the bolt on the front of the wedge. More information on laser aligning a gantry can be found on our previous article here.
Safety during installation
Lift hooks are provided for manoeuvring each machine, but some of the more lightweight and smaller milling rails, such as the LMR range are capable of being lifted into position by 2 people.
The information provided in this article is merely intended to provide an insight into the various set up methods. Setting up a milling machine on-site should only be carried out by suitably trained and qualified personnel and normal safety procedures must be carried out to avoid the possibility of an accident occurring.
You can find out more about Mirage milling machines by getting in touch with your regional Mirage contact here or by downloading the Linear Milling Buyers Guide.