FMC Technologies, Dunfermline, has invested over £2 million in a Fastems flexible manufacturing system (FMS) to streamline production of components for subsea control modules (SCMs) that fit into the company’s Christmas trees, which control the flow of oil from a well.
Around a dozen sizes of a family of four tightly toleranced components are machined – a 316 stainless steel hydraulic manifold block, a mild steel base plate, and stainless steel high-pressure and low-pressure adapter plates. Process capability of Cpk 1.67 is achieved, reliably and repeatably, even when the system is run unattended.
Main elements of the FMS are two Okuma MA-600HB twin-pallet, horizontal-spindle machining centres from NCMT linked by a Fastems multi-level automated storage and retrieval system for handling machine pallets and raw material. It maximises uptime of both spindles by ensuring prompt delivery of new work fixtured on pallets.
Additional benefits of adopting an FMS solution, rather than fixturing parts at the second pallet of each machine, include increased production flexibility, reduced lead times and less labour associated with transporting and storing pallets, allowing operators to carry out additional tasks while machining is in progress.
Of high capacity compared with its footprint, the 26-metre long, two-level Fastems store can hold twenty-four 630 x 630 mm machine pallets and thirty-two 800 x 1,200 mm Europallets of billets. The system is capable of 72 transfers per hour.
Two workpiece load / unload stations each have a rotary table with 8 x 45-degree indexing to assist set-up and machined part removal. The manual door at the front and the automatic roller shutter at the rear through which the pallet accesses the store are interlinked so that they cannot open simultaneously, ensuring operator safety. An adjacent input/output station conveniently delivers raw material from the store to the loading area.
Defined by a production schedule downloaded from FMC Technologies’ host computer into the Fastems MMS Windows-based software controlling the FMS, a fixtured billet is delivered automatically to whichever machining centre becomes available first. Running at up to 2.5 m/s on rails in an aisle along the length of the store, a 3-axis CNC stacker crane with a three-metre mast, lifting carriage and telescopic forks effects pallet transfers to a positioning accuracy of ± 3 mm.
At the same time as the MMS schedules a pallet transfer, the correct NC program number is sent to the relevant Okuma control and the cycle is activated when the pallet reaches the machine. Finished components are delivered back into the racking or directly to one of the set-up stations for removal and dispatch to Norway for assembly.
A chip is attached to each toolholder containing 10 lines of information concerning the cutter, including length, radius offsets and remaining life. When a tool is exchanged into a spindle from the 285-tool magazine fitted to each machining centre, the data is corroborated by laser probe. The Fastems MMS has an integral tool management module to track and manage the movement of tooling throughout the FMS via its connection with the machine controls.
MMS has a simulation software module, allowing evaluation of whether the available machining capacity is sufficient for the planned production. Different scenarios can be tested by including, excluding and modifying the due dates and order status. Results are displayed as both a bar graph and Gantt chart.
The main window in the Fastems control displays a mimic of the entire system and uses colours and icons to advise the real-time status of all FMS elements. Active production orders are displayed in a work list window and are sorted by their dynamic priority. The window also displays on separate rows all of the operations of an individual production order. The status of the production resources for each operation is displayed separately, ie machining and material pallets, NC programs, tools and raw materials in storage.
Operators effectively work in a paperless environment, as set-up sheets, tooling data and setting details are all stored electronically. Information is transmitted upstream after completion of each machining cycle, enabling full statistical reporting on FMS utilisation and management overview of production.
The modular Fastems system can be extended to cope with future increases in production volumes. Indeed, when laying the foundations for the FMS at Dunfermline, provision was made to add a third machining centre, ensuring sufficient capacity for all SCM modules well into the future.