Product category:
Flexible machining cells and systems (FMS)
News Release from: Fastems Divisions, Helvar | Subject: Automated pallet storage and retrieval system
Edited by the Manufacturingtalk Editorial
Team on 09 April 2002
FMS cuts more metal than setting-up
As the production manager in any jobbing shop will tell you, some components take so long to set up that a whole day can go by without metal being cut, until you set up an FMS.
As the production manager in any jobbing shop will tell you, some components take so long to set up that a whole day can go by without metal being cut Worthing-based subcontractor, Roscomac, often found this to be the case and developed during busy periods an ingenious, if crude, method of setting up some components off-line and craning them on and off a 6-pallet pool machining centre
This article was originally published on Manufacturingtalk on 14 Jul 2000 at 8.00am (UK)
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Since December 2001, however, the company has used a far more sophisticated and productive flexible manufacturing system (FMS) to machine complex components requiring long set-ups.
It is based on an automated storage and retrieval system (ASRS) supplied by Fastems' Factory Automated Systems division in Finland that holds machine pallets and delivers them to three HS500 half-metre-cube, horizontal machining centres from Hitachi Seiki.
The system was installed within two months of order and operating round the clock two days after commissioning.
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Said Roscomac's Managing Director, Joe Martello, "We saw similar pallet handling and management systems at a number of machine tool suppliers, particularly in Japan, and were convinced that this was the way manufacturing industry should be going.
Pallet pools are not flexible enough any more with the ever increasing complexity of parts and the faster turnround expected by customers.
"However, we did not want to be tied in to machine tools from one supplier as we expanded our FMS, so we opted for open integrator, Fastems, whose systems are able to serve almost any make and type of machine tool.
We inspected a number of similar systems operating in the UK, one of which is installed at our biggest customer, before making our final decision." Noteworthy is that the Roscomac installation is the first in Europe where Fastems has linked to HS500 machines; and is the only one where the Finnish company has interfaced its high level tool management and DNC software to Hitachi Seiki machine tools.
Another first is the link between the Fastems controller and the machine controls via Fanuc's FOCAS 1 Ethernet interface.
This is the name given to drivers and libraries that provide communication with and programmable access to the latest Fanuc i-Series of 'open factory' CNC systems, as fitted to the Hitachi Seiki machines, enabling Fastems' control of DNC and tool management over an Ethernet link.
Roscomac consolidated its business under one roof in Dominion Way, Worthing in July last year and in so doing it became obvious that the company had significant capacity and potential for growth.
It now operates more than 80 lathes, machining centres and grinders, the vast majority of them CNC, and has spent GBP5 million on new production equipment in the last four years alone.
Various factors were restricting growth and profitability, however, among them the shortage of skilled staff.
Mr Martello also wanted to reduce inventory and work-in-progress and lessen the workload in the inspection department.
Phase 1 of the FMS project was embarked upon, involving the three Hitachi Seiki HS500 machining centres each with a 120-tool magazine linked by a Fastems three-level, linear store for 54 machine pallets, although only 32 pallets were purchased at the outset.
Two load-unload stations were included for removing machined components and fixturing new parts prior to them entering the system.
Within 12 months it is Mr Martello's intention to proceed with Phase 2 by purchasing another three HS500s, extending the pallet store by an extra 38 positions and adding another load-unload station.
Thereafter, although no firm plans have been made, it is possible that a further FMS will be installed based on a machining centre, lathe and grinder linked by a separate Fastems ASRS.
Although Roscomac has been operating the FMS for only a short time, already the benefits are showing and efficiency levels are up.
In the first six weeks of operation, 12 of the more complex jobs that were difficult to set and needed up to 50 minutes' machining time had been produced in the system.
A further two parts per week will be added for the foreseeable future.
The opportunity is being taken to re-engineer existing jobs by optimising programs and reducing the number of set-ups in many instances.
For example, one component which used to take 45 minutes to produce has been transformed by fixturing three at a time and machining them in a total of 30 minutes.
Another job involved three successive clampings that used to take a total of 2 to 3 days to set, whereas now it is machined in a single hit.
Frequently, parts will be part-machined on one HS500 and transferred to another for a subsequent operation according to which tools are in the respective magazines.
Extensive in-cycle deburring is now often included to minimise hand finishing; and the higher speeds and feeds of the new machines are exploited as well as their through-tool coolant capability, resulting in much faster cycle times.
As soon as a new job comes in and is allocated to the FMS, it is scheduled into the system on a FIFO (first-in, first-out) basis unless a rush order needs to be given priority by the operator.
An advantage is that jobs can be interspersed to satisfy early deliveries of first-off parts to different customers, allowing orders to be turned round faster.
The controller sends each successive NC program number to a machining centre and initiates the cycle.
The control screen makes good use of colour graphics including a mimic of the entire FMS to provide comprehensive system and job monitoring capabilities.
Every tool in the FMS is monitored as to its position within the system and its remaining life as well as the location of sister tools if they exist.
At the front of the program for each job is a tool list with cutting times, allowing the Fastems MMS (Manufacturing Management System) control to carry out tool magazine planning.
This evaluates which machine is capable of producing the components fixtured on the pallet.
By utilising tool simulation software, the system can also check to see whether any tool will exceed its preset life before the end of the production run.
If tool changes are required, the control will show a list of sister tools needed and identify which tools may be removed without affecting the production, allowing the extra tools to be added.
If a tool should break mid-cycle and there is no sister replacement, a message appears on the operator screen.
Should this occur during unattended overnight operation, the system has the intelligence to reject the pallet and select the next one, ready loaded and waiting in the storage rack, and send it to the machine.
The relevant pallet is locked out and given a red marker on the Fastems screen with details of which part of the program has not been completed and why.
An engineering decision can then be made as to how best to complete the job.
Meanwhile the FMS will have proceeded with the next jobs in the queue.
If this happens to be an identical part, it will be sent to one of the other HS500s provided it has the requisite tools.
Other jobs will be allocated to the first machine provided the broken tool is not needed to complete the operations.
The system always tries to find available resources to complete the workpieces loaded.
"Enhanced tool management and rationalisation have been a major benefit of the FMS project," continued Mr Martello.
"Previously we would create a new tooling list without looking at what was already available on the shop floor, which resulted in cutters being duplicated.
"I estimate that the FMS will halve the number of tools that would otherwise have been needed by the individual machine tools.
Moreover it allows us to keep much tighter control over them in respect of their remaining life and their location." A further possible option offered by Fastems is 'Resource Level Management II - MMS4200 Tool Manager', allowing a pre-setter to be linked into the system and tools to be tracked and managed even when they are outside the machine tool magazines in an external tool hive.
Roscomac may consider this in the future.
Efficient production management is the main benefit of the FMS, dovetailing in with Roscomac's supply contracts based on schedule, direct line feed or kan ban.
Any size of batch is now economic although they rarely fall below 20-off.
Controlling the system is the upgraded Fastems MMS version 2.1, which offers enhanced performance including improved graphical functionality, an easier user interface, automatic recovery after power failure and easier access to data sheets containing information such as set-up instructions attached to the pallets.
Like its predecessor software, it is entirely PC-embedded and uses inverter drives for greater flexibility, doing away with the older PLC units.
The software runs on a PC under Windows to provide integrated control over all functions of the FMS.
It connects not only with the machines' CNC systems, but also the loading stations and stacker crane via Profibus technology.
Within the scope of MMS, in addition to control over movement of the hardware elements, program download and job scheduling, is the ability to monitor the utilisation of the stacker crane and load stations, and also to offer advanced diagnostics.
The latter shows all events, warnings and alarms of devices connected to the system and can be interrogated via a modem by engineers in Finland who have the ability to rectify problems and upgrade the system, thus saving time and money.
In many cases this eliminates the need for a service engineer to visit and the consequent loss of production if the system is down for an extended period.
Additionally, the software produces a log file that enables shift patterns to be analysed and optimised.
Concluded Joe Martello, "I cannot see us going from our current 80 staff to above 100 now that we have gone the FMS route, so savings in labour costs will be considerable.
It is a very efficient method of production and although we are not there yet, other users report 99+ per cent system availability and well into the 90s for production up-time over 24 hour working.".
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