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Fastems offers flexible Manufacture - Midlands Subcontractor

Fastems offers flexible Manufacture - Midlands Subcontractor

Added to MTDCNC by MTDCNC on 07 August 2010

A contract machinist in the Midlands has been enjoying the benefits of flexible manufacture since 2005, when it installed a Fastems store to house thirty 630 mm machine pallets and deliver them automatically to a pair of Mori Seiki horizontal machining centres (HMC). A couple of years later, the store was extended to 66 pallet locations on three levels and two more HMCs were added, another Mori Seiki and a Mazak that was relocated from elsewhere in the factory.

The company has now taken advantage of the system&rsquos open architecture and flexibility of design to undertake a major reconfiguration and further expansion. Another Mori Seiki 630 mm-pallet HMC has been added to sit in line with the other four machining centres at the front of the flexible manufacturing system (FMS).

In addition, a Fastems automated deburring cell, which is also capable of part marking, was sited opposite the Mazak on the same floor level, but at the back of the store.

At the same time, to make room for the Mazak and provide space for a sixth machining centre, two workpiece fixturing stations were moved from the front to the back of the FMS, but on a lower level, and a third was created to cope with increased throughput.

A major difficulty was that the floor level at the back is one metre lower, due to the factory being located on a hill. Fastems overcame the problem by constructing three inclined, powered conveyors, about five metres long, to bring the machine pallets to a point on the lower level where operators could gain access to the fixtures for loading and unloading components.

A few years ago, an extra station for accessing pallets from the system was added at the front to allow technicians to inspect components without disrupting production. At that time, the store was extended a small distance in the other direction to accommodate the station, underlining the extensive retrofit options that are available to Fastems FMS users.

Cellular manufacture

Back in 2005, before the two-machine FMS was purchased, the 60 machine tools on the shop floor were arranged conventionally by machine type. It resulted in poor flexibility of planning and production, long lead times and bottlenecks of part-machined batches of components around the factory. So the subcontractor decided to relocate 90 per cent of the plant into cells dedicated to producing parts for major customers.

The benefit was that raw material, whether forgings, castings or billets, went into the cells and finished components came out. Lead times were shorter, as they were only a function of the machining time in the cell. Productivity and quality were greatly improved and work in progress was significantly reduced.

However, in some instances, very small batch sizes were combined with complex setting that could exceed the run-time for the components. The company recognised that an FMS was the answer to producing such components economically.

Zero setting time

With the Fastems system, setting times have been eliminated from the production time, even for very small batches, as all components are set off-line and housed in the store ready to be called up by the system controller for allocation to a machine. So it is now just as easy to make one part as it is to produce 100.

The company has re-engineered over 120 different parts to run in the FMS, 24 hours a day, and is achieving 90 per cent utilisation of the machines linked into the system.

The FMS is capable of higher uptime, into the high 90s, but customers tend to change their minds at the last minute. The subcontractor often collects a consignment of free-issue material that is quite different from what was expected and has to enter the changes into the Fastems controller.

Another issue is that the five machining centres are fitted with 120-tool magazines, which gives 600 tools, whereas the company uses a total of 900 in its FMS machines. So tool changes limit the uptime that could otherwise be achieved.&rdquo

Around three-quarters of parts going through the FMS used to be destined for a major manufacturer of off-road vehicles. However, a reduction in volumes triggered by the downturn in the construction industry meant that the subcontractor had to transfer other parts to the system, resulting in significant economies in production costs.

According to the company, the FMS is the most cost-effective method of producing prismatically machined components. The subcontractor makes a higher margin on all of the parts that are transferred to it from stand-alone machining centres, irrespective of batch size.

Two extra contracts recently won in the defence and petrochemical sectors will also be fulfilled in the FMS. Both are low-volume, regular call-off contracts that would have been uneconomic without the FMS. It is noteworthy that the system itself is a powerful sales tool when the subcontractor is pitching for new business.

Robotic part marking and deburring

An additional stipulation by the defence customer was that every component should be marked for traceability, which will be accommodated economically by the Fastems robot cell. Part marking will have a second advantage for the customer, as the eight parts will also be numbered to assist assembly.

The subcontractor was aware that customers were generally becoming more interested in component identification and discussions had been ongoing with the off-road vehicle manufacturer. The subcontractor was aware that deburring was consuming an increasing amount of operator time, which was the trigger for investment in the Fastems robot cell and its integration into the FMS. The cell is equipped with a Fanuc 6-axis robot and tool changer to allow automatic exchange of both deburring and marking tools.

So far, around half of components that go through the FMS have been reprogrammed for automatic deburring and the process is ongoing. Many components have to be effectively and consistently deflashed, as after washing they are delivered line-side to OEMs for immediate assembly.

At present, one less operator is needed to run the FMS as a result of installing the robotic deburrer. Two operators and a technician are now sufficient to handle the system. Another operator will be released for other duties when deburring programs have been incorporated into all of the relevant production cycles. Part marking will be gained &lsquofor free&rsquo, as no extra labour will be involved.

Fastems control system

Controlling FMS production is Fastems&rsquo Windows-based MMS (manufacturing management system) software. Its core tasks are control of the stacker crane and scheduling automatic pallet transfers between the loading stations, pallet locations and machine tools.

When a pallet is sent from a loading station into the system, a route is assigned to it and the system automatically controls the defined sequence of steps. It ensures that the correct NC programs are downloaded over DNC links to the appropriate machine tool(s) and are instigated when the job reaches the top of the queue and the pallet arrives at the machine.

The main window in the control displays a mimic of the entire system and uses colours and icons to advise the real-time status of all the FMS elements.

Conclusion

The subcontractor concluded by stating that the provision of CNC subcontract machining capacity has become a commodity. High quality is expected and buyers speak only in terms of machining hours.

The FMS allows parts in low to medium volumes to be offered at high-volume production prices. Each machine in the FMS operates at least twice as productively as it would were it used in stand-alone mode, because fixtured parts are always ready to present to the spindles. It adds up to a productivity advantage with which non-FMS users struggle to compete.

When a sixth machining centre is added in due course, the facility will be even more cost effective. By that time, the 3-axis CNC stacker crane will be at 85 per cent capacity serving six machining centres, the robot cell and three load / unload stations. No further extension to the FMS will then be practicable and a second system will be considered for another of the company&rsquos facilities.

 


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