As part of the drive to achieve order-driven lean manufacturing, the installation of Seiki Systems DNC and shopfloor data collection (SFDC) system at Parker Hannifin of Rotherham has reduced CNC program download to an almost instantaneous event. As a result the company has gained at least another two hours production time a day for each of the 19 CNC machines installed. Roy Hanson, Services Superintendent, said that as the company reduces the size of its production batches.
Batches were between one and 1,000 parts to an average of 50, production control was demanding between 50 and 100 separate CNC machine set-ups per day, so the 20 minutes or so taken for program insertion was proving to be very costly.
He says: 'The Seiki Systems DNC facility has certainly been effective in increasing machine availability, allowing us to support smaller batch quantities and thereby reducing stock levels throughout the sites that we service.
Program maintenance is also so very straightforward now and takes just a couple of minutes rather than half an hour or more.' He describes how the installation of DNC was a first step in Parker Hannifin's paper-less manufacturing and included centralised download of schedules, tool sheets and component drawings.
'At first there was some shopfloor resistance to the whole idea, and to SFDC in particular.
However, as the project has advanced, the shop floor has come to value the system almost as much as management.
We now have two of our seven cells running in a totally paper-less environment and the plan is to have the entire manufacturing area running this way,' he says.
The Rotherham factory produces a variety of 'non-stroking' components for supply to sister factories within Parker Hannifin's hydraulics division.
These sites are located in Germany, Italy, France and the USA as well as Watford in the UK.
Parts are machined using milling, drilling and/or turning from castings, billet, bar and flame cut blanks in mild steel, brass and cast iron.
Parts are produced to a general machining tolerance of +/-0.02 mm.
However, some dimensions are held to +/- 0.01 mm.
Roy Hanson explained: 'About 10 years ago we changed from departmental manufacture to cell-based manufacturing.
Each cell is associated with a family of parts such as heads, glands, caps, accumulators or pistons and comprises all the facilities needed to machine the parts to completion.
As inspection is carried out in accordance with a QS 9000 compliant quality system, this has already vastly reduced the floor time and distance travelled by individual components during manufacture.
As part of our future improvement plans we hope to include packing for dispatch within each cell, which then makes them totally self-contained.' Introducing DNC for program download was a logical progression but became a major priority as batch quantities reduced.
The number of individual parts produced by each cell ranges from 30 to well over 100 and total machining time can be as little as four minutes spread over two or three CNC machining operations.
'As batch quantities reduced, our attention quickly focussed on lowering set-up times and program management offered so much potential,' maintains Roy Hanson.
He explains: 'We examined a number of DNC systems but the outstanding feature of the Seiki Systems offering was its user friendliness.
In particular, we appreciated the return file comparison system which automatically identifies shop floor edits to the issued program; it's such a brilliant aspect of the system and one of the best that we tried.
The SFDC capability was a bonus, we were already filling in manual time sheets but they provided a fairly low level of detail.
The Seiki Systems software has provided much more information without any increase in effo rt.' The Seiki Systems software was installed on an existing token ring network and the number of terminals per cell depends on the number of operators.
Mostly, there is one terminal for each operator though use of the system to issue tooling sheets and drawings may lead to this increasing to one per machine.
Operator input to the data collection screens is by light pen and each CNC machine has its own allocation of tailored screens for SFDC.
However, the company is also considering expanding the scope of the data collection network to embrace eight conventional machines as well.
With the DNC capability established, the system has quickly evolved into a fully interactive shop floor data facility.
It now links with Parker Hannifin's J D Edwards MRP system, which provides each cell with a prioritised production schedule.
Calling up an item from this list provides each machine with a folder comprising the tooling sheets and program.
On two cells, this has recently been expanded to include the component drawing as well.
Says Roy Hanson: 'A key quality benefit of electronic drawing issue is that jobs are always sent out with the most up-to-date version.' At cell level, the operators can book in the number of parts made and parts rejected or scrapped as applicable.
This also provides a degree of automated inventory control.
In addition, the Seiki Systems SFDC facility provides a detailed breakdown of activity for each CNC machine allowing off-line analysis using a variety of colour-coded graphics.
This provides shopfloor supervision with access to status reporting at any time via an on-screen graphics that correspond to the shop floor layout.
'As we've worked with the system we've identified areas where additional gains can be made as the overall effect of supplying data electronically has been very positive,' Roy Hanson confirmed.
'With SFDC we obtain a very detailed breakdown of machine activity that has allowed us to identify and remedy weak areas.
At the moment, the principal shortcoming is that it isn't applied to the conventional machines in the cells but that is reasonably straightforward to rectify.
Certainly the system has overcome the initial misgivings of the staff and is now well acknowledged as a benefit by all.' Expansions to the system will probably include increasing the number of terminals to one-per-machine and the addition of printing set-up diagrams and drawing data is also under consideration.
SFDC has been very important in Roy Hanson's view in that it has allowed quantified benefits of changes to be assessed and to identify areas where further improvement can be made.
'All in all, it has been a very cost-effective investment and has certainly drawn the attention of other manufacturing sites within the parent company.
Most important, we now have total program reliability,' he maintains.